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Weapon of mass destruction

A weapon of mass destruction (WMD) is a biological, chemical, radiological, nuclear, or any other weapon that can kill or significantly harm many people or cause great damage to artificial structures (e.g., buildings), natural structures (e.g., mountains), or the biosphere. The scope and usage of the term has evolved and been disputed, often signifying more politically than technically. Originally coined in reference to aerial bombing with chemical explosives during World War II, it has later come to refer to large-scale weaponry of warfare-related technologies, such as biological, chemical, radiological, or nuclear warfare.

Early uses of this term
The first use of the term "weapon of mass destruction" on record is by Cosmo Gordon Lang, Archbishop of Canterbury, in 1937 in reference to the aerial bombing of Guernica, Spain:

"Who can think at this present time without a sickening of the heart of the appalling slaughter, the suffering, the manifold misery brought by war to Spain and to China? Who can think without horror of what another widespread war would mean, waged as it would be with all the new weapons of mass destruction?"

At the time, nuclear weapons had not been developed. Japan conducted research on biological weapons, and chemical weapons had seen wide battlefield use in World War I. Their use was outlawed by the Geneva Protocol of 1925. Italy used mustard agent against civilians and soldiers in Ethiopia in 1935–36.

Following the atomic bombings of Hiroshima and Nagasaki that ended World War II and during the Cold War, the term came to refer more to non-conventional weapons. The application of the term to specifically nuclear and radiological weapons is traced by William Safire to the Russian phrase "Оружие массового поражения" – oruzhiye massovogo porazheniya (weapon of mass destruction).

William Safire credits James Goodby (of the Brookings Institution) with tracing what he considers the earliest known English-language use soon after the nuclear bombing of Hiroshima and Nagasaki (although it is not quite verbatim): a communique from a 15 November 1945, meeting of Harry Truman, Clement Attlee and Mackenzie King (probably drafted by Vannevar Bush, as Bush claimed in 1970) referred to "weapons adaptable to mass destruction."

Safire says Bernard Baruch used that exact phrase in 1946 (in a speech at the United Nations probably written by Herbert Bayard Swope). The phrase found its way into the very first resolution the United Nations General assembly adopted in January 1946 in London, which used the wording "the elimination from national armaments of atomic weapons and of all other weapons adaptable to mass destruction." The resolution also created the Atomic Energy Commission (predecessor of the International Atomic Energy Agency (IAEA)).

An exact use of this term was given in a lecture titled "Atomic Energy as a Contemporary Problem" by J. Robert Oppenheimer. He delivered the lecture to the Foreign Service and the State Department, on 17 September 1947.

"It is a very far reaching control which would eliminate the rivalry between nations in this field, which would prevent the surreptitious arming of one nation against another, which would provide some cushion of time before atomic attack, and presumably therefore before any attack with weapons of mass destruction, and which would go a long way toward removing atomic energy at least as a source of conflict between the powers."

The term was also used in the introduction to the hugely influential U.S. government document known as NSC 68 written in 1950.

During a speech at Rice University on 12 September 1962, President John F. Kennedy spoke of not filling space "with weapons of mass destruction, but with instruments of knowledge and understanding." The following month, during a televised presentation about the Cuban Missile Crisis on 22 October 1962, Kennedy made reference to "offensive weapons of sudden mass destruction."

An early use of the exact phrase in an international treaty is in the Outer Space Treaty of 1967, but the treaty provides no definition of the phrase, and the treaty also categorically prohibits the stationing of "weapons" and the testing of "any type of weapon" in outer space, in addition to its specific prohibition against placing in orbit, or installing on celestial bodies, "any objects carrying nuclear weapons or any other kinds of weapons of mass destruction."

Evolution of its use
During the Cold War, the term "weapons of mass destruction" was primarily a reference to nuclear weapons. At the time, in the West the euphemism "strategic weapons" was used to refer to the American nuclear arsenal. However, there is no precise definition of the "strategic" category, neither considering range nor yield of the nuclear weapon.

Subsequent to Operation Opera, the destruction of a pre-operational nuclear reactor inside Iraq by the Israeli Air Force in 1981, the Israeli prime minister, Menachem Begin, countered criticism by saying that "on no account shall we permit an enemy to develop weapons of mass destruction against the people of Israel." This policy of pre-emptive action against real or perceived weapons of mass destruction became known as the Begin Doctrine.

The term "weapons of mass destruction" continued to see periodic use, usually in the context of nuclear arms control; Ronald Reagan used it during the 1986 Reykjavík Summit, when referring to the 1967 Outer Space Treaty. Reagan's successor, George H. W. Bush, used the term in a 1989 speech to the United Nations, primarily in reference to chemical arms.

The end of the Cold War reduced U.S. reliance on nuclear weapons as a deterrent, causing it to shift its focus to disarmament. With the 1990 invasion of Kuwait and 1991 Gulf War, Iraq's nuclear, biological, and chemical weapons programs became a particular concern of the first Bush Administration. Following the war, Bill Clinton and other western politicians and media continued to use the term, usually in reference to ongoing attempts to dismantle Iraq's weapons programs. After the 11 September 2001 attacks and the 2001 anthrax attacks in the United States, an increased fear of nonconventional weapons and asymmetric warfare took hold in many countries. The fear reached a crescendo with the 2002 Iraq disarmament crisis and the alleged existence of weapons of mass destruction in Iraq that became the primary justification for the 2003 invasion of Iraq; however, American forces found none in Iraq. They found old stockpiles of chemical munitions including sarin and mustard agents, but all were considered to be unusable because of corrosion or degradation. Iraq, however, declared a chemical weapons stockpile in 2009 which U.N. personnel had secured after the 1991 Gulf War. The stockpile contained mainly chemical precursors, but some munitions remained usable.

Because of its prolific use and (worldwide) public profile during this period, the American Dialect Society voted "weapons of mass destruction" (and its abbreviation, "WMD") the word of the year in 2002, and in 2003 Lake Superior State University added WMD to its list of terms banished for "Mis-use, Over-use and General Uselessness" (and "as a card that trumps all forms of aggression").

In its criminal complaint against the main suspect of the Boston Marathon bombing of 15 April 2013, the FBI refers to a pressure-cooker improvised bomb as a "weapon of mass destruction."

There have been calls to classify at least some classes of cyber weapons as WMD, in particular those aimed to bring about large-scale (physical) destruction, such as by targeting critical infrastructure. However, some scholars have objected to classifying cyber weapons as WMD on the grounds that they "cannot [currently] directly injure or kill human beings as efficiently as guns or bombs" or clearly "meet the legal and historical definitions" of WMD.

Strategic definition
The most widely used definition of "weapons of mass destruction" is that of nuclear, biological, or chemical weapons (NBC) although there is no treaty or customary international law that contains an authoritative definition. Instead, international law has been used with respect to the specific categories of weapons within WMD, and not to WMD as a whole. While nuclear, chemical and biological weapons are regarded as the three major types of WMDs, some analysts have argued that radiological materials as well as missile technology and delivery systems such as aircraft and ballistic missiles could be labeled as WMDs as well.

However, there is an argument that nuclear and biological weapons do not belong in the same category as chemical and "dirty bomb" radiological weapons, which have limited destructive potential (and close to none, as far as property is concerned), whereas nuclear and biological weapons have the unique ability to kill large numbers of people with very small amounts of material, and thus could be said to belong in a class by themselves.

The NBC definition has also been used in official U.S. documents, by the U.S. President, the U.S. Central Intelligence Agency, the U.S. Department of Defense,  and the U.S. Government Accountability Office.

Other documents expand the definition of WMD to also include radiological or conventional weapons. The U.S. military refers to WMD as: "Chemical, biological, radiological, or nuclear weapons capable of a high order of destruction or causing mass casualties and exclude the means of transporting or propelling the weapon where such means is a separable and divisible part from the weapon. Also called WMD." This may also refer to nuclear ICBMs (intercontinental ballistic missiles).

The significance of the words separable and divisible part of the weapon is that missiles such as the Pershing II and the SCUD are considered weapons of mass destruction, while aircraft capable of carrying bombloads are not.

In 2004, the United Kingdom's Butler Review recognized the "considerable and long-standing academic debate about the proper interpretation of the phrase 'weapons of mass destruction. The committee set out to avoid the general term but when using it, employed the definition of United Nations Security Council Resolution 687, which defined the systems which Iraq was required to abandon:
 * "Nuclear weapons or nuclear-weapons-usable material or any sub-systems or components or any research, development, support or manufacturing facilities relating to [nuclear weapons].
 * Chemical and biological weapons and all stocks of agents and all related subsystems and components and all research, development, support and manufacturing facilities.
 * Ballistic missiles with a range greater than 150 kilometres and related major parts, and repair and production facilities."

Chemical weapons expert Gert G. Harigel considers only nuclear weapons true weapons of mass destruction, because "only nuclear weapons are completely indiscriminate by their explosive power, heat radiation and radioactivity, and only they should therefore be called a weapon of mass destruction". He prefers to call chemical and biological weapons "weapons of terror" when aimed against civilians and "weapons of intimidation" for soldiers.

Testimony of one such soldier expresses the same viewpoint. For a period of several months in the winter of 2002–2003, U.S. Deputy Secretary of Defense Paul Wolfowitz frequently used the term "weapons of mass terror", apparently also recognizing the distinction between the psychological and the physical effects of many things currently falling into the WMD category.

Gustavo Bell Lemus, the Vice President of Colombia, at 9 July 2001 United Nations Conference on the Illicit Trade in Small Arms and Light Weapons in All Its Aspects, quoted the Millennium Report of the UN Secretary-General to the General Assembly, in which Kofi Annan said that small arms could be described as WMD because the fatalities they cause "dwarf that of all other weapons systems – and in most years greatly exceed the toll of the atomic bombs that devastated Hiroshima and Nagasaki".

An additional condition often implicitly applied to WMD is that the use of the weapons must be strategic. In other words, they would be designed to "have consequences far outweighing the size and effectiveness of the weapons themselves". The strategic nature of WMD also defines their function in the military doctrine of total war as targeting the means a country would use to support and supply its war effort, specifically its population, industry, and natural resources.

Within U.S. civil defense organizations, the category is now Chemical, Biological, Radiological, Nuclear, and Explosive (CBRNE), which defines WMD as:

"(1) Any explosive, incendiary, poison gas, bomb, grenade, or rocket having a propellant charge of more than four ounces [113 g], missile having an explosive or incendiary charge of more than one-quarter ounce [7 g], or mine or device similar to the above. (2) Poison gas. (3) Any weapon involving a disease organism. (4) Any weapon that is designed to release radiation at a level dangerous to human life."

Military definition
For the general purposes of national defense, the U.S. Code defines a weapon of mass destruction as:
 * any weapon or device that is intended, or has the capability, to cause death or serious bodily injury to a significant number of people through the release, dissemination, or impact of:
 * toxic or poisonous chemicals or their precursors
 * a disease organism
 * radiation or radioactivity

For the purposes of the prevention of weapons proliferation, the U.S. Code defines weapons of mass destruction as "chemical, biological, and nuclear weapons, and chemical, biological, and nuclear materials used in the manufacture of such weapons".

Criminal (civilian) definition
For the purposes of U.S. criminal law concerning terrorism, weapons of mass destruction are defined as:
 * any "destructive device" defined as any explosive, incendiary, or poison gas – bomb, grenade, rocket having a propellant charge of more than four ounces, missile having an explosive or incendiary charge of more than one-quarter ounce, mine, or device similar to any of the devices described in the preceding clauses
 * any weapon that is designed or intended to cause death or serious bodily injury through the release, dissemination, or impact of toxic or poisonous chemicals, or their precursors
 * any weapon involving a biological agent, toxin, or vector
 * any weapon that is designed to release radiation or radioactivity at a level dangerous to human life

The Federal Bureau of Investigation's definition is similar to that presented above from the terrorism statute:
 * any "destructive device" as defined in Title 18 USC Section 921: any explosive, incendiary, or poison gas – bomb, grenade, rocket having a propellant charge of more than four ounces, missile having an explosive or incendiary charge of more than one-quarter ounce, mine, or device similar to any of the devices described in the preceding clauses
 * any weapon designed or intended to cause death or serious bodily injury through the release, dissemination, or impact of toxic or poisonous chemicals or their precursors
 * any weapon involving a disease organism
 * any weapon designed to release radiation or radioactivity at a level dangerous to human life
 * any device or weapon designed or intended to cause death or serious bodily injury by causing a malfunction of or destruction of an aircraft or other vehicle that carries humans or of an aircraft or other vehicle whose malfunction or destruction may cause said aircraft or other vehicle to cause death or serious bodily injury to humans who may be within range of the vector in its course of travel or the travel of its debris.

Indictments and convictions for possession and use of WMD such as truck bombs, pipe bombs, shoe bombs, and cactus needles coated with a biological toxin have been obtained under 18 USC 2332a.

As defined by 18 USC §2332 (a), a Weapon of Mass Destruction is: Under the same statute, conspiring, attempting, threatening, or using a Weapon of Mass Destruction may be imprisoned for any term of years or for life, and if resulting in death, be punishable by death or by imprisonment for any terms of years or for life. They can also be asked to pay a maximum fine of $250,000.
 * (A) any destructive device as defined in section 921 of the title;
 * (B) any weapon that is designed or intended to cause death or serious bodily injury through the release, dissemination, or impact of toxic or poisonous chemicals, or their precursors;
 * (C) any weapon involving a biological agent, toxin, or vector (as those terms are defined in section 178 of this title); or
 * (D) any weapon that is designed to release radiation or radioactivity at a level dangerous to human life;

The Washington Post reported on 30 March 2006: "Jurors asked the judge in the death penalty trial of Zacarias Moussaoui today to define the term 'weapons of mass destruction' and were told it includes airplanes used as missiles". Moussaoui was indicted and tried for conspiracy to both destroy aircraft and use weapons of mass destruction, among others.

The surviving Boston Marathon bombing perpetrator, Dzhokhar Tsarnaev, was charged in June 2013 with the federal offense of "use of a weapon of mass destruction" after he and his brother Tamerlan Tsarnaev allegedly placed crude shrapnel bombs, made from pressure cookers packed with ball bearings and nails, near the finish line of the Boston Marathon. He was convicted in April 2015. The bombing resulted in three deaths and at least 264 injuries.

International law
The development and use of WMD is governed by several international conventions and treaties.

Nuclear weapons
Nuclear weapons use the energy inside of an atom's nucleus to create massive explosions. This goal is achieved through nuclear fission and fusion.

Nuclear fission is when the nucleus of an atom is split into smaller nuclei. This process can be induced by shooting a neutron at the nucleus of an atom. When the neutron is absorbed by the atom, it becomes unstable, causing it to split and release energy. Modern nuclear weapons start this process by detonating chemical explosives around a pit of either uranium-235 or plutonium-239 metal. The force from this detonation is directed inwards, causing the pit of uranium or plutonium to compress to a dense point. Once the uranium/plutonium is dense enough, neutrons are then injected. This starts a fission chain reaction also known as an atomic explosion.

Nuclear fusion is essentially the opposite of fission. It is the fusing together of nuclei, not the splitting of it. When exposed to extreme pressure and temperature, some lightweight nuclei can fuse together and form heavier nuclei, releasing energy in the process. Interestingly, fusion weapons (also known as “thermonuclear” or “hydrogen” weapons) use the fission process to initiate fusion. Fusion weapons use the energy released from a fission explosion to fuse hydrogen isotopes together. The energy released from these weapons creates a fireball, which reaches tens of million degrees. A temperature of this magnitude is similar to the temperature found at center of the sun, so it shouldn't be any surprise to learn that the sun runs on fusion as well.

The only country to have used a nuclear weapon in war is the United States, which dropped two atomic bombs on the Japanese cities of Hiroshima and Nagasaki during World War II.

At the start of 2023, nine states—the United States, Russia, the United Kingdom, France, China, India, Pakistan, the Democratic People's Republic of Korea (DPRK, or North Korea) and Israel—together possessed approximately 12 512 nuclear weapons, of which 9576 were considered to be potentially operationally available. An estimated 3844 of these warheads were deployed with operational forces, including about 2000 that were kept in a state of high operational alert—the same number as the previous year. South Africa developed a small nuclear arsenal in the 1980s but disassembled them in the early 1990s, making it the only country to have fully given up an independently developed nuclear weapons arsenal. Belarus, Kazakhstan, and Ukraine inherited stockpiles of nuclear arms following the break-up of the Soviet Union, but relinquished them to the Russian Federation.

Countries where nuclear weapons are deployed through nuclear sharing agreements include Belgium, Germany, Italy, the Netherlands, and Turkey.

Biological weapons
The history of biological warfare goes back at least to the Mongol siege of Caffa in 1346 and possibly much farther back to antiquity. It is believed that the Ancient Greeks contaminated their adversaries' wells by placing animal corpses in them. However, only by the turn of the 20th century did advances in microbiology allow for the large-scale weaponization of pathogens. During First World War, German military attempted to introduce anthrax into Allied livestock. In Second World War, Japan conducted aerial attacks on China using fleas carrying the bubonic plague. During the 20th century, at least nine states have operated offensive biological weapons programs, including Canada (1946–1956), France (1921–1972), Iraq (1985–1990s), Japan (1930s–1945), Rhodesia, South Africa (1981–1993), the Soviet Union (1920s–1992), the United Kingdom (1934–1956), and the United States (1943–1969). The Japanese biological weapons program, which was run by the secret Imperial Japanese Army Unit 731 during the Sino-Japanese War (1937–1945), became infamous for conducting often fatal human experiments on prisoners and producing biological weapons for combat use. The Soviet Union covertly operated the world's largest, longest, and most sophisticated biological weapons program, in violation of its obligations under international law.

International restrictions on biological warfare began with the 1925 Geneva Protocol, which prohibits the use but not the possession or development of biological and chemical weapons. Upon ratification of the Geneva Protocol, several countries made reservations regarding its applicability and use in retaliation. Due to these reservations, it was in practice a "no-first-use" agreement only. The 1972 Biological Weapons Convention (BWC) supplements the Geneva Protocol by prohibiting the development, production, acquisition, transfer, stockpiling, and use of biological weapons. Having entered into force on 26 March 1975, the BWC was the first multilateral disarmament treaty to ban the production of an entire category of weapons of mass destruction. As of March 2021, 183 states have become party to the treaty.

Chemical weapons
Chemical weapons have been used around the world by various civilizations since ancient times. The oldest reported case of a chemical substance being used as a weapon was in 256 AD  during the siege of Dura-Europos. A mixture of tar and sulfur was used to produce sulfur oxides, which helped take control of the city. In the industrial era, chemical weapons were used extensively by both sides during World War I, and by the Axis powers during World War II (both in battle and in extermination camp gas chambers) though Allied powers also stockpiled them.

International restrictions on chemical warfare began with the Hague Conventions of 1899 and 1907, and was expanded significantly by the 1925 Geneva Protocol. These treaties prohibited the use of poisons or chemical agents in international warfare, but did not place restrictions on development or weapon stockpiles. Since 1997, the Chemical Weapons Convention (CWC) has expanded restrictions to prohibit any use and development of chemical weapons except for very limited purposes (research, medical, pharmaceutical or protective). As of 2018, a handful of countries have known inventories, and many are in the process of being safely destroyed. Nonetheless, proliferation and use in war zones remains an active concern, most recently the use of chemical weapons in the Syrian Civil War.

Ethics and international legal status
Some commentators classify some or all the uses of nuclear, chemical, or biological weapons during wartime as a war crime (or crime against humanity if widespread) because they kill civilians (who are protected by the laws of war) indiscriminately or are specifically prohibited by international treaties (which have become more comprehensive over time). Proponents of use say that specific uses of such weapons have been necessary for defense or to avoid more deaths in a protracted war. The tactic of terror bombing from aircraft, and generally targeting cities with area bombardment or saturation carpet bombing has also been criticized, defended, and prohibited by treaty in the same way; the destructive effect of conventional saturation bombing is similar to that of a nuclear weapon.

United States politics
Due to the potentially indiscriminate effects of WMD, the fear of a WMD attack has shaped political policies and campaigns, fostered social movements, and has been the central theme of many films. Support for different levels of WMD development and control varies nationally and internationally. Yet understanding of the nature of the threats is not high, in part because of imprecise usage of the term by politicians and the media.

Fear of WMD, or of threats diminished by the possession of WMD, has long been used to catalyze public support for various WMD policies. They include mobilization of pro- and anti-WMD campaigners alike, and generation of popular political support. The term WMD may be used as a powerful buzzword or to generate a culture of fear. It is also used ambiguously, particularly by not distinguishing among the different types of WMD.

A television commercial called Daisy, promoting Democrat Lyndon Johnson's 1964 presidential candidacy, invoked the fear of a nuclear war and was an element in Johnson's subsequent election.

Later, United States' President George W. Bush used the threat of potential WMD in Iraq as justification for the 2003 invasion of Iraq. Broad reference to Iraqi WMD in general was seen as an element of President Bush's arguments. The claim that Iraq possessed Weapons of Mass Destruction (WMD) was a major factor that led to the invasion of Iraq in 2003 by Coalition forces.

Over 500 munitions containing mustard agent and sarin were discovered throughout Iraq since 2003; they were made in the 1980s and are no longer usable as originally intended due to corrosion.

The American Heritage Dictionary defines a weapon of mass destruction as: "a weapon that can cause widespread destruction or kill large numbers of people, especially a nuclear, chemical, or biological weapon." In other words, it does not have to be nuclear, biological or chemical (NBC). For example, Dzhokhar Tsarnaev, one of the perpetrators of the Boston Marathon bombing, was charged under United States law 18 U.S.C. 2332A for using a weapon of mass destruction and that was a pressure cooker bomb. In other words, it was a weapon that caused large-scale death and destruction, without being an NBC weapon.

Media coverage
In March 2004, the Center for International and Security Studies at Maryland (CISSM) released a report examining the media's coverage of WMD issues during three separate periods: nuclear weapons tests by India and Pakistan in May 1998; the U.S. announcement of evidence of a North Korean nuclear weapons program in October 2002; and revelations about Iran's nuclear program in May 2003. The CISSM report argues that poor coverage resulted less from political bias among the media than from tired journalistic conventions. The report's major findings were that:

"1. Most media outlets represented WMD as a monolithic menace, failing to adequately distinguish between weapons programs and actual weapons or to address the real differences among chemical, biological, nuclear, and radiological weapons.

2. Most journalists accepted the Bush administration's formulation of the 'War on Terror' as a campaign against WMD, in contrast to coverage during the Clinton era, when many journalists made careful distinctions between acts of terrorism and the acquisition and use of WMD.

3. Many stories stenographically reported the incumbent administration's perspective on WMD, giving too little critical examination of the way officials framed the events, issues, threats, and policy options.

4. Too few stories proffered alternative perspectives to official line, a problem exacerbated by the journalistic prioritizing of breaking-news stories and the 'inverted pyramid' style of storytelling."

In a separate study published in 2005, a group of researchers assessed the effects reports and retractions in the media had on people's memory regarding the search for WMD in Iraq during the 2003 Iraq War. The study focused on populations in two coalition countries (Australia and the United States) and one opposed to the war (Germany). Results showed that U.S. citizens generally did not correct initial misconceptions regarding WMD, even following disconfirmation; Australian and German citizens were more responsive to retractions. Dependence on the initial source of information led to a substantial minority of Americans exhibiting false memory that WMD were indeed discovered, while they were not. This led to three conclusions:
 * 1) The repetition of tentative news stories, even if they are subsequently disconfirmed, can assist in the creation of false memories in a substantial proportion of people.
 * 2) Once information is published, its subsequent correction does not alter people's beliefs unless they are suspicious about the motives underlying the events the news stories are about.
 * 3) When people ignore corrections, they do so irrespective of how certain they are that the corrections occurred.

A poll conducted between June and September 2003 asked people whether they thought evidence of WMD had been discovered in Iraq since the war ended. They were also asked which media sources they relied upon. Those who obtained their news primarily from Fox News were three times as likely to believe that evidence of WMD had been discovered in Iraq than those who relied on PBS and NPR for their news, and one third more likely than those who primarily watched CBS.

Based on a series of polls taken from June–September 2003.

In 2006, Fox News reported the claims of two Republican lawmakers that WMDs had been found in Iraq, based upon unclassified portions of a report by the National Ground Intelligence Center. Quoting from the report, Senator Rick Santorum said "Since 2003, coalition forces have recovered approximately 500 weapons munitions which contain degraded mustard or sarin nerve agent". According to David Kay, who appeared before the U.S. House Armed Services Committee to discuss these badly corroded munitions, they were leftovers, many years old, improperly stored or destroyed by the Iraqis. Charles Duelfer agreed, stating on NPR's Talk of the Nation: "When I was running the ISG – the Iraq Survey Group – we had a couple of them that had been turned in to these IEDs, the improvised explosive devices. But they are local hazards. They are not a major, you know, weapon of mass destruction."

Later, wikileaks would show that WMDs of these kinds continued to be found as the Iraqi occupation continued.

Many news agencies, including Fox News, reported the conclusions of the CIA that, based upon the investigation of the Iraq Survey Group, WMDs are yet to be found in Iraq.

Public perceptions
Awareness and opinions of WMD have varied during the course of their history. Their threat is a source of unease, security, and pride to different people. The anti-WMD movement is embodied most in nuclear disarmament, and led to the formation of the British Campaign for Nuclear Disarmament in 1957.

In order to increase awareness of all kinds of WMD, in 2004 the nuclear physicist and Nobel Peace Prize winner Joseph Rotblat inspired the creation of The WMD Awareness Programme to provide trustworthy and up to date information on WMD worldwide.

In 1998, the University of New Mexico's Institute for Public Policy released their third report on U.S. perceptions – including the general public, politicians and scientists – of nuclear weapons since the breakup of the Soviet Union. Risks of nuclear conflict, proliferation, and terrorism were seen as substantial.

While maintenance of the U.S. nuclear arsenal was considered above average in importance, there was widespread support for a reduction in the stockpile, and very little support for developing and testing new nuclear weapons.

Also in 1998, nuclear weapons became an issue in India's election of March, in relation to political tensions with neighboring Pakistan. Prior to the election the Bharatiya Janata Party (BJP) announced it would "declare India a nuclear weapon state" after coming to power.

BJP won the elections, and on 14 May, three days after India tested nuclear weapons for the second time, a public opinion poll reported that a majority of Indians favored the country's nuclear build-up.

On 15 April 2004, the Program on International Policy Attitudes (PIPA) reported that U.S. citizens showed high levels of concern regarding WMD, and that preventing the spread of nuclear weapons should be "a very important U.S. foreign policy goal", accomplished through multilateral arms control rather than the use of military threats.

A majority also believed the United States should be more forthcoming with its biological research and its Nuclear Non-Proliferation Treaty commitment of nuclear arms reduction.

A Russian opinion poll conducted on 5 August 2005 indicated half the population believed new nuclear powers have the right to possess nuclear weapons. 39% believed the Russian stockpile should be reduced, though not eliminated.

In popular culture
Weapons of mass destruction and their related impacts have been a mainstay of popular culture since the beginning of the Cold War, as both political commentary and humorous outlet. The actual phrase "weapons of mass destruction" has been used similarly and as a way to characterise any powerful force or product since the Iraqi weapons crisis in the lead up to the Coalition invasion of Iraq in 2003. Science-fiction may introduce novel weapons of mass destruction with much greater yields or impact than anything in reality.

Radioactive weaponry or hazard symbol
The international radioactivity symbol (also known as trefoil) first appeared in 1946, at the University of California, Berkeley Radiation Laboratory. At the time, it was rendered as magenta, and was set on a blue background.

It is drawn with a central circle of radius R, the blades having an internal radius of 1.5R and an external radius of 5R, and separated from each other by 60°. It is meant to represent a radiating atom.

The International Atomic Energy Agency found that the trefoil radiation symbol is unintuitive and can be variously interpreted by those uneducated in its meaning; therefore, its role as a hazard warning was compromised as it did not clearly indicate "danger" to many non-Westerners and children who encountered it. As a result of research, a new radiation hazard symbol (ISO 21482) was developed in 2007 to be placed near the most dangerous parts of radiation sources featuring a skull, someone running away, and using a red rather than yellow background.

The red background is intended to convey urgent danger, and the sign is intended to be used on equipment where very strong ionizing radiation can be encountered if the device is dismantled or otherwise tampered with. The intended use of the sign is not in a place where the normal user will see it, but in a place where it will be seen by someone who has started to dismantle a radiation-emitting device or equipment. The aim of the sign is to warn people such as scrap metal workers to stop work and leave the area.

Biological weaponry or hazard symbol

Developed by Dow Chemical company in the 1960s for their containment products.

According to Charles Dullin, an environmental-health engineer who contributed to its development:

"'We wanted something that was memorable but meaningless, so we could educate people as to what it means.'"

Definition and origin

 * "WMD: Words of mass dissemination" (12 February 2003), BBC News.
 * Bentley, Michelle, "War and/of Worlds: Constructing WMD in U.S. Foreign Policy", Security Studies 22 (Jan. 2013), 68–97.
 * Michael Evans, "What makes a weapon one of mass destruction?" (6 February 2004), The Times.
 * Bruce Schneier, "Definition of 'Weapon of Mass Destruction'" (6 April 2009), Schneier on Security.
 * Stefano Felician, Le armi di distruzione di massa, CEMISS, Roma, 2010,

International law

 * United Nations Security Council Resolution 1540
 * David P. Fidler, "Weapons of Mass Destruction and International Law" (February 2003), American Society of International Law.
 * Joanne Mariner, "FindLaw Forum: Weapons of mass destruction and international law's principle that civilians cannot be targeted" (20 November 2001), CNN.

Media

 * , by Susan D. Moeller, Center for International and Security Studies at Maryland, 2004.
 * Memory for fact, fiction, and misinformation, by Stephan Lewandowsky, Werner G.K. Stritzke, Klaus Oberauer, and Michael Morales, Psychological Science, 16(3): 190–195, 2005.

Ethics

 * Jacob M. Appel, "Is All Fair in Biological Warfare?", Journal of Medical Ethics, June 2009.

Public perceptions

 * Steven Kull et al., Americans on WMD Proliferation (15 April 2004), Program on International Policy Attitudes/Knowledge Networks survey.

title: Weapon of mass destruction


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Nuclear utilization target selection

Nuclear utilization target selection (NUTS) is a hypothesis regarding the use of nuclear weapons often contrasted with mutually assured destruction (MAD). NUTS theory at its most basic level asserts that it is possible for a limited nuclear exchange to occur and that nuclear weapons are simply one more rung on the ladder of escalation pioneered by Herman Kahn. This leads to a number of other conclusions regarding the potential uses of and responses to nuclear weapons.

Counterforce strikes
A counterforce strike consists of an attack on enemy nuclear weapons meant to destroy them before they can be used. A viable first strike capability would require the ability to launch a 100-percent-effective (or nearly so) counterforce attack. Such an attack is made more difficult by systems such as early warning radars which allow the possibility for rapid recognition and response to a nuclear attack and by systems such as submarine-launched ballistic missiles or road-mobile nuclear missiles (such as the Soviet SS-20) which make nuclear weapons harder to locate and target.

Since a limited nuclear war is a viable option for a NUTS theorist, the power to unleash such attacks holds a great deal of appeal. However, establishing such a capability is very expensive. A counterforce weapon requires a much more accurate warhead than a countervalue weapon, as it must be guaranteed to detonate very close to its target, which drastically increases relative costs.

Limited countervalue strikes
Some NUTS theorists hold that a mutually assured destruction-type deterrent is not credible in cases of a small attack, such as one carried out on a single city, as it is suicidal. In such a case, an overwhelming nuclear response would destroy every enemy city and thus every potential hostage that could be used to influence the attacker's behavior. This would free up the attacker to launch further attacks and remove any chance for the attacked nation to bargain. A country adhering to a NUTS-style war plan would likely respond to such an attack with a limited attack on one or several enemy cities.

Missile defense
Since NUTS theory assumes the possibility of a winnable nuclear war, the contention of many MAD theorists that missile defense systems should be abandoned as a destabilizing influence is generally not accepted by NUTS theorists. For NUTS theorists, a missile defence system would be a positive force in that it would protect against a limited nuclear attack. Additionally, such a system would increase the odds of success for a counterforce attack by assuring that if some targets escaped the initial attack, the incoming missiles could be intercepted. But protection against a limited attack means that the opponent has incentive to launch a larger scale attack, against which the defence is likely to be ineffective. Additionally, increased possibility of success of counterforce attacks means that the opponent has the incentive to launch a preventive attack, which increases the risk of a large scale response to misinterpreted signals.

NUTS and US nuclear strategy
NUTS theory can be seen in the US adoption of a number of first-strike weapons, such as the Trident II and Minuteman III nuclear missiles, which both have an extremely low circular error probable (CEP) of about 90 meters for the former and 120 meters for the latter. These weapons are accurate enough to almost certainly destroy a missile silo if it is targeted.

Additionally, the US has proceeded with a number of programs which improve its strategic situation in a nuclear confrontation. The Stealth bomber has the capacity to carry a large number of stealthy cruise missiles, which could be nuclear-tipped, and due to its low probability of detection and long range would be an excellent weapon with which to deliver a first strike.

During the late 1970s and the 1980s, the Pentagon began to adopt strategies for limited nuclear options to make it possible to control escalation and reduce the risk of all-out nuclear war, hence accepting NUTS. In 1980, President Jimmy Carter signed Presidential Directive 59 which endorsed the NUTS strategic posture committed to fight and win a nuclear war, and accepted escalation dominance and flexible response. The Soviets, however, were skeptical of limited options or the possibility of controlling escalation. While Soviet deterrence doctrine posited massive responses to any nuclear use ("all against any"), military officials considered the possibility of proportionate responses to a limited US attack, although they "doubted that nuclear war could remain limited for long."

Like several other nuclear powers, but unlike China and India, the United States has never made a "no first use" pledge, maintaining that pledging not to use nuclear weapons before an opponent would undermine their deterrent. NATO plans for war with the USSR called for the use of tactical nuclear weapons in order to counter Soviet numerical superiority.

Rather than making extensive preparations for battlefield nuclear combat in Central Europe, the Soviet General Staff emphasized conventional military operations and believing that they had an advantage there. "The Soviet military leadership believed that conventional superiority provided the Warsaw Pact with the means to approximate the effects of nuclear weapons and achieve victory in Europe without resort to those weapons."

In criticising US policy on nuclear weapons as contradictory, leftist philosopher Slavoj Zizek has suggested that NUTS is the policy of the US with respect to Iran and North Korea while its policy with respect to Russia and China is one of mutual assured destruction (MAD).

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Nuclear utilization target selection


text:
Metempsychosis

In philosophy, metempsychosis (μετεμψύχωσις) is the transmigration of the soul, especially its reincarnation after death. The term is derived from ancient Greek philosophy, and has been recontextualized by modern philosophers such as Arthur Schopenhauer, Kurt Gödel, Mircea Eliade, and Magdalena Villaba; otherwise, the word "transmigration" is more appropriate. The word plays a prominent role in James Joyce's Ulysses and is also associated with Nietzsche. Another term sometimes used synonymously is palingenesis.

Orphism
The Orphic religion, which believed in metempsychosis, first appeared in Thrace on the northeastern frontier. Orpheus, its legendary Thracian founder, is said to have taught that soul and body are united by a compact unequally binding on either. The soul is divine but immortal and aspires to freedom, while the body holds it in fetters as a prisoner. Death dissolves that contract but only to reimprison the liberated soul after a short time, for the wheel of birth revolves inexorably. Thus, the soul continues its journey and alternates between a separate unrestrained existence and a fresh reincarnation around the wide circle of necessity, as the companion of many bodies of men and animals. To those unfortunate prisoners, Orpheus proclaims the message of liberation, that they stand in need of the grace of redeeming gods, Dionysus in particular, and calls them to turn to the gods by ascetic piety and self-purification: the purer their lives, the higher their next reincarnation will be, until the soul has completed the spiral ascent of destiny to live forever as a God from whom it comes. Such was the teaching of Orphism, which appeared in Greece about the 6th century BCE, organized itself into private and public mysteries at Eleusis and elsewhere, and produced copious literature.

Pre-Socratic philosophy
The earliest Greek thinker with whom metempsychosis is connected is Pherecydes of Syros, but Pythagoras, who is said to have been his pupil, is its first famous philosophic exponent. Walter Burkert has argued that Pythagoras may have introduced metempsychosis to Orphism. He suggests that modern scholarship's tendency to separate Orphism from early Pythagoreanism is a retrojection, possibly of Nietzschean ideas about the opposition of the Apollonian (associated with Pythagoreanism) and the Dionysian (associated with Orphism), whereas for the Greeks, Apollo and Dionysus were brothers and not so clearly differentiated. Pythagoras offered as evidence for metempsychosis his own recollection of past lives, a superhuman form of wisdom that contributed to his reputation as a prophet.

Platonic philosophy
The weight and importance of metempsychosis in the Western tradition are from its adoption by Plato. In the eschatological myth that closes the Republic, he tells how Er, the son of Armenius, miraculously returned to life on the twelfth day after death and recounted the secrets of the other world. After death, he said, he went with others to the place of Judgment and saw the souls returning from heaven, and proceeded with them to a place where they chose new lives, human and animal. He saw the soul of Orpheus changing into a swan, Thamyras becoming a nightingale, musical birds choosing to be men, and Atalanta choosing the honours of an athlete. Men were seen passing into animals and wild and tame animals changing into each other. After their choice, the souls drank of Lethe and then shot away like stars to their birth. There are myths and theories to the same effect in other dialogues, including the Phaedrus, Meno, Phaedo, Timaeus, and Laws. In Plato's view the number of souls was fixed; souls are never created or destroyed but only transmigrate from one body to another.

Modern
Scholars have debated the extent of Plato's belief in metempsychosis since at least the Renaissance. Marsilio Ficino argued that Plato's references to metempsychosis were intended to be allegorical. Modern scholars, including Chad Jorgensen and Gerard Naddaf, have tended to agree with Ficino.

"Metempsychosis" is the title of a longer work by the metaphysical poet John Donne, written in 1601. The poem, also known as the Infinitati Sacrum, consists of two parts, the "Epistle" and "The Progress of the Soule". In the first line of the latter part, Donne writes that he "sing[s] of the progresse of a deathlesse soule".

Metempsychosis is a recurring theme in James Joyce's modernist novel Ulysses (1922). In Joycean fashion, the word famously appears in Leopold Bloom's inner monologue recalling how his wife, Molly Bloom, apparently mispronounced it earlier that day as "met him pike hoses."

title: Metempsychosis


text:
Fragile X syndrome

Fragile X syndrome (FXS) is a genetic disorder characterized by mild-to-moderate intellectual disability. The average IQ in males with FXS is under 55, while about two thirds of affected females are intellectually disabled. Physical features may include a long and narrow face, large ears, flexible fingers, and large testicles. About a third of those affected have features of autism such as problems with social interactions and delayed speech. Hyperactivity is common, and seizures occur in about 10%. Males are usually more affected than females.

This disorder and finding of fragile X syndrome has an X-linked dominant inheritance. It is typically caused by an expansion of the CGG triplet repeat within the FMR1 (fragile X messenger ribonucleoprotein 1) gene on the X chromosome. This results in silencing (methylation) of this part of the gene and a deficiency of the resultant protein (FMRP), which is required for the normal development of connections between neurons. Diagnosis requires genetic testing to determine the number of CGG repeats in the FMR1 gene. Normally, there are between 5 and 40 repeats; fragile X syndrome occurs with more than 200. A premutation is said to be present when the gene has between 55 and 200 repeats; females with a premutation have an increased risk of having an affected child. Testing for premutation carriers may allow for genetic counseling.

There is no cure. Early intervention is recommended, as it provides the most opportunity for developing a full range of skills. These interventions may include special education, speech therapy, physical therapy, or behavioral therapy. Medications may be used to treat associated seizures, mood problems, aggressive behavior, or ADHD. Fragile X syndrome tends to show more symptoms on affected males since females have another X chromosome which can compensate for the damaged one.

Signs and symptoms
Most young children do not show any physical signs of FXS. It is not until puberty that physical features of FXS begin to develop. Aside from intellectual disability, prominent characteristics of the syndrome may include an elongated face, large or protruding ears, flat feet, larger testes (macroorchidism), and low muscle tone. Recurrent otitis media (middle ear infection) and sinusitis is common during early childhood. Speech may be cluttered or nervous. Behavioral characteristics may include stereotypic movements (e.g., hand-flapping) and atypical social development, particularly shyness, limited eye contact, memory problems, and difficulty with face encoding. Some individuals with fragile X syndrome also meet the diagnostic criteria for autism.

Males with a full mutation display virtually complete penetrance and will therefore almost always display symptoms of FXS, while females with a full mutation generally display a penetrance of about 50% as a result of having a second, normal X chromosome. Females with FXS may have symptoms ranging from mild to severe, although they are generally less affected than males due to variability in X-inactivation.

Physical phenotype

 * Large, protruding ears (both)
 * Long face (vertical maxillary excess)
 * High-arched palate (related to the above)
 * Hyperextensible finger joints
 * Hyperextensible thumbs ('double-jointed')
 * Flat feet
 * Soft skin
 * Postpubescent macroorchidism (large testicles in males after puberty)
 * Hypotonia (low muscle tone)

Intellectual development
Individuals with FXS may present anywhere on a continuum from learning disabilities in the context of a normal intelligence quotient (IQ) to severe intellectual disability, with an average IQ of 40 in males who have complete silencing of the FMR1 gene. Females, who tend to be less affected, generally have an IQ which is normal or borderline with learning difficulties. The main difficulties in individuals with FXS are with working and short-term memory, executive function, visual memory, visual-spatial relationships, and mathematics, with verbal abilities being relatively unaffected.

Data on intellectual development in FXS are limited. However, there is some evidence that standardized IQ decreases over time in the majority of cases, apparently as a result of slowed intellectual development. A longitudinal study looking at pairs of siblings where one child was affected and the other was not found that affected children had an intellectual learning rate which was 55% slower than unaffected children.

Individuals with FXS often demonstrated language and communicative problems. This may be related to muscle function of the mouth and frontal-lobe deficits.

Autism
Fragile X syndrome co-occurs with autism in many cases and is a suspected genetic cause of the autism in these cases. This finding has resulted in screening for FMR1 mutation to be considered mandatory in children diagnosed with autism. Of those with fragile X syndrome, prevalence of concurrent autism spectrum disorder (ASD) has been estimated to be between 15 and 60%, with the variation due to differences in diagnostic methods and the high frequency of autistic features in individuals with fragile X syndrome not meeting the DSM criteria for an ASD.

Although individuals with FXS have difficulties in forming friendships, those with FXS and ASD characteristically also have difficulties with reciprocal conversation with their peers. Social withdrawal behaviors, including avoidance and indifference, appear to be the best predictors of ASD in FXS, with avoidance appearing to be correlated more with social anxiety while indifference was more strongly correlated to ASD. When both autism and FXS are present, a greater language deficit and lower IQ is observed as compared to children with only FXS.

Genetic mouse models of FXS have also been shown to have autistic-like behaviors.

Social interaction
FXS is characterized by social anxiety, including poor eye contact, gaze aversion, prolonged time to commence social interaction, and challenges forming peer relationships. Social anxiety is one of the most common features associated with FXS, with up to 75% of males in one series characterized as having excessive shyness and 50% having panic attacks. Social anxiety in individuals with FXS is related to challenges with face encoding, the ability to recognize a face that one has seen before.

It appears that individuals with FXS are interested in social interaction and display greater empathy than groups with other causes of intellectual disability, but display anxiety and withdrawal when placed in unfamiliar situations with unfamiliar people. This may range from mild social withdrawal, which is predominantly associated with shyness, to severe social withdrawal, which may be associated with co-existing autism spectrum disorder.

Females with FXS frequently display shyness, social anxiety and social avoidance or withdrawal. In addition, premutation in females has been found to be associated with social anxiety.

Female individuals with FXS show decreased activation in the prefrontal regions of the brain.

Mental health
Attention deficit hyperactivity disorder (ADHD) is found in the majority of males with FXS and 30% of females, making it the most common psychiatric diagnosis in those with FXS. Children with fragile X have very short attention spans, are hyperactive, and show hypersensitivity to visual, auditory, tactile, and olfactory stimuli. These children have difficulty in large crowds due to the loud noises and this can lead to tantrums due to hyperarousal. Hyperactivity and disruptive behavior peak in the preschool years and then gradually decline with age, although inattentive symptoms are generally lifelong.

Aside from the characteristic social phobia features, a range of other anxiety symptoms are very commonly associated with FXS, with symptoms typically spanning a number of psychiatric diagnoses but not fulfilling any of the criteria in full. Children with FXS pull away from light touch and can find textures of materials to be irritating. Transitions from one location to another can be difficult for children with FXS. Behavioral therapy can be used to decrease the child's sensitivity in some cases. Behaviors such as hand flapping and biting, as well as aggression, can be an expression of anxiety.

Perseveration is a common communicative and behavioral characteristic in FXS. Children with FXS may repeat a certain ordinary activity over and over. In speech, the trend is not only in repeating the same phrase but also talking about the same subject continually. Cluttered speech and self-talk are commonly seen. Self-talk includes talking with oneself using different tones and pitches. Although only a minority of FXS cases will meet the criteria for obsessive–compulsive disorder (OCD), a significant majority will have symptoms of obsession. However, as individuals with FXS generally find these behaviors pleasurable, unlike individuals with OCD, they are more frequently referred to as stereotypic behaviors.

Mood symptoms in individuals with FXS rarely meet diagnostic criteria for a major mood disorder as they are typically not of sustained duration. Instead, these are usually transient and related to stressors, and may involve labile (fluctuating) mood, irritability, self-injury and aggression.

Individuals with fragile X-associated tremor/ataxia syndrome (FXTAS) are likely to experience combinations of dementia, mood, and anxiety disorders. Males with the FMR1 premutation and clinical evidence of FXTAS were found to have increased occurrence of somatization, obsessive–compulsive disorder, interpersonal sensitivity, depression, phobic anxiety, and psychoticism.

Vision
Ophthalmologic problems include strabismus. This requires early identification to avoid amblyopia. Surgery or patching are usually necessary to treat strabismus if diagnosed early. Refractive errors in patients with FXS are also common.

Neurology
Individuals with FXS are at a higher risk of developing seizures, with rates between 10% and 40% reported in the literature. In larger study populations the frequency varies between 13% and 18%, consistent with a recent survey of caregivers which found that 14% of males and 6% of females experienced seizures. The seizures tend to be partial, are generally not frequent, and are amenable to treatment with medication.

Individuals who are carriers of premutation alleles are at risk for developing fragile X-associated tremor/ataxia syndrome (FXTAS), a progressive neurodegenerative disease. It is seen in approximately half of male carriers over the age of 70, while penetrance in females is lower. Typically, onset of tremor occurs in the sixth decade of life, with subsequent progression to ataxia (loss of coordination) and gradual cognitive decline.

Working memory
From their 40s onward, males with FXS begin developing progressively more severe problems in performing tasks that require the central executive of working memory. Working memory involves the temporary storage of information 'in mind', while processing the same or other information. Phonological memory (or verbal working memory) deteriorates with age in males, while visual-spatial memory is not found to be directly related to age. Males often experience an impairment in the functioning of the phonological loop. The CGG length is significantly correlated with central executive and the visual–spatial memory. However, in a premutation individual, CGG length is only significantly correlated with the central executive, not with either phonological memory or visual–spatial memory.

Fertility
About 20% of women who are carriers for the fragile X premutation are affected by fragile X-related primary ovarian insufficiency (FXPOI), which is defined as premature menopause, which is menopause occurring before 40 years of age (average age at menopause is 51 years old in the US). The number of CGG repeats correlates with penetrance and age of onset, but it is not a linear relationship. However premature menopause is more common in premutation carriers than in women with the full mutation, and the highest risk for FXPOI is observed in women with between 70-100 repeats the risk of FXPOI. Fragile X-associated primary ovarian insufficiency (FXPOI) is one of three Fragile X-associated Disorders (FXD) caused by changes in the FMR1 gene. FXPOI affects female premutation carriers, of which is caused by the FMR1 gene, when their ovaries are not functioning properly. Women with FXPOI may exhibit changes in menstrual cycles and have changes in hormone levels but not be considered menopausal. Women with FXPOI still have the chance to get pregnant in about 10% of cases, because their ovaries occasionally release viable eggs through "escape" ovulation.

FMRP is a chromatin-binding protein that functions in the DNA damage response. FMRP also occupies sites on meiotic chromosomes and regulates the dynamics of the DNA damage response machinery during spermatogenesis.

Causes
Fragile X syndrome is a genetic disorder which occurs as a result of a mutation of the Fragile X Messenger Ribonucleoprotein 1 (FMR1) gene on the X chromosome, most commonly an increase in the number of CGG trinucleotide repeats in the 5' untranslated region of FMR1. Mutation at that site is found in 1 out of about every 2000 males and 1 out of about every 259 females. Incidence of the disorder itself is about 1 in every 3600 males and 1 in 4000–6000 females. Although this accounts for over 98% of cases, FXS can also occur as a result of point mutations affecting FMR1.

In unaffected individuals, the FMR1 gene contains 5–44 repeats of the sequence CGG, most commonly 29 or 30 repeats. Between 45 and 54 repeats is considered a "grey zone", with a premutation allele generally considered to be between 55 and 200 repeats in length. Individuals with fragile X syndrome have a full mutation of the FMR1 allele, with over 200 CGG repeats. In these individuals with a repeat expansion greater than 200, there is methylation of the CGG repeat expansion and FMR1 promoter, leading to the silencing of the FMR1 gene and a lack of its product.

This methylation of FMR1 in chromosome band Xq27.3 is believed to result in constriction of the X chromosome which appears 'fragile' under the microscope at that point, a phenomenon that gave the syndrome its name. One study found that FMR1 silencing is mediated by the FMR1 mRNA. The FMR1 mRNA contains the transcribed CGG-repeat tract as part of the 5' untranslated region, which hybridizes to the complementary CGG-repeat portion of the FMR1 gene to form an RNA·DNA duplex.

A subset of people with intellectual disability and symptoms resembling fragile X syndrome are found to have point mutations in FMR1. This subset lacked the CGG repeat expansion in FMR1 traditionally associated with fragile x syndrome. The first complete DNA sequence of the repeat expansion in someone with the full mutation was generated by scientists in 2012 using SMRT sequencing.

Inheritance
Fragile X syndrome has traditionally been considered an X-linked dominant condition with variable expressivity and possibly reduced penetrance. The likelihood of transmission depends on the parent's sex, the X chromosome carrying the mutation, and the number of CGG repeats in the premutation.

Due to genetic anticipation and X-inactivation in females, the inheritance of Fragile X syndrome does not follow the usual pattern of X-linked dominant inheritance, and scholars from The University of Chicago Medical Center and Groningen University Hospital have had an abstract published in the American Journal of Medical Genetics that proposes discontinuing labeling X-linked disorders as dominant or recessive. Males with a full mutation are usually affected and infertile, while carrier females have a 50% chance of passing the mutation.

Before the FMR1 gene was discovered, analysis of pedigrees showed the presence of male carriers who were asymptomatic, with their grandchildren affected by the condition at a higher rate than their siblings suggesting that genetic anticipation was occurring. This tendency for future generations to be affected at a higher frequency became known as the Sherman paradox after its description in 1985. Due to this, male children often have a greater degree of symptoms than their mothers.

The explanation for this phenomenon is that male carriers pass on their premutation to all of their daughters, with the length of the FMR1 CGG repeat typically not increasing during meiosis, the cell division that is required to produce sperm. Incidentally, males with a full mutation only pass on premutations to their daughters. However, females with a full mutation are able to pass this full mutation on, so theoretically there is a 50% chance that a child will be affected. In addition, the length of the CGG repeat frequently does increase during meiosis in female premutation carriers due to instability and so, depending on the length of their premutation, they may pass on a full mutation to their children who will then be affected. Repeat expansion is considered to be a consequence of strand slippage either during DNA replication or DNA repair synthesis.

Mosaicism
Mosaicism refers to cases where individuals have both full mutation and premutation copies. Mosaicism can result from instability in the CGG repeats, and affected individuals may show classic symptoms, although some evidence suggests higher intellectual abilities compared to those with a full mutation. 1

Pathophysiology
FMRP is found throughout the body, but in highest concentrations within the brain and testes. It appears to be primarily responsible for selectively binding to around 4% of mRNA in mammalian brains and transporting it out of the cell nucleus and to the synapses of neurons. Most of these mRNA targets have been found to be located in the dendrites of neurons, and brain tissue from humans with FXS and mouse models shows abnormal dendritic spines, which are required to increase contact with other neurons. The subsequent abnormalities in the formation and function of synapses and development of neural circuits result in impaired neuroplasticity, an integral part of memory and learning. Connectome changes have long been suspected to be involved in the sensory pathophysiology and most recently a range of circuit alterations have been shown, involving structurally increased local connectivity and functionally decreased long-range connectivity.

In addition, FMRP has been implicated in several signalling pathways that are being targeted by a number of drugs undergoing clinical trials. The group 1 metabotropic glutamate receptor (mGluR) pathway, which includes mGluR1 and mGluR5, is involved in mGluR-dependent long term depression (LTD) and long term potentiation (LTP), both of which are important mechanisms in learning. The lack of FMRP, which represses mRNA production and thereby protein synthesis, leads to exaggerated LTD. FMRP also appears to affect dopamine pathways in the prefrontal cortex which is believed to result in the attention deficit, hyperactivity and impulse control problems associated with FXS. The downregulation of GABA pathways, which serve an inhibitory function and are involved in learning and memory, may be a factor in the anxiety symptoms which are commonly seen in FXS.

Research in a mouse model of FSX shows that cortical neurons receive reduced sensory information (hyposensitivity), contrary to the common assumption that these neurons are hypersensitive, accompanied by enhanced contextual information, accumulated from previous experiences. Therefore, these results suggest that the hypersensitive phenotype of affected individuals might arise from mismatched contextual input onto these neurons.

Diagnosis
Clinical diagnosis relies on identifying a variant of FMR1 associated with decreased function alongside moderate to severe intellectual impairment, particularly in males or moderate in females. Diagnostic tests include PCR to analyze the number of CGG repeats, Southern blot analysis, and examination of AGG trinucleotides in the FMR1 gene region.

Cytogenetic analysis for fragile X syndrome was first available in the late 1970s when diagnosis of the syndrome and carrier status could be determined by culturing cells in a folate deficient medium and then assessing for "fragile sites" (discontinuity of staining in the region of the trinucleotide repeat) on the long arm of the X chromosome. This technique proved unreliable, however, as the fragile site was often seen in less than 40% of an individual's cells. This was not as much of a problem in males, but in female carriers, where the fragile site could generally only be seen in 10% of cells, the mutation often could not be visualised.

Since the 1990s, more sensitive molecular techniques have been used to determine carrier status. The fragile X abnormality is now directly determined by analysis of the number of CGG repeats using polymerase chain reaction (PCR) and methylation status using Southern blot analysis. By determining the number of CGG repeats on the X chromosome, this method allows for more accurate assessment of risk for premutation carriers in terms of their own risk of fragile X associated syndromes, as well as their risk of having affected children. Because this method only tests for expansion of the CGG repeat, individuals with FXS due to missense mutations or deletions involving FMR1 will not be diagnosed using this test and should therefore undergo sequencing of the FMR1 gene if there is clinical suspicion of FXS.

Prenatal testing with chorionic villus sampling or amniocentesis allows diagnosis of FMR1 mutation while the fetus is in utero and appears to be reliable.

Early diagnosis of fragile X syndrome or carrier status is important for providing early intervention in children or fetuses with the syndrome, and allowing genetic counselling with regards to the potential for a couple's future children to be affected. Most parents notice delays in speech and language skills, difficulties in social and emotional domains as well as sensitivity levels in certain situations with their children.

Management
There is no cure for the underlying defects of FXS. Management of FXS may include speech therapy, behavioral therapy, occupational therapy, special education, or individualised educational plans, and, when necessary, treatment of physical abnormalities. Persons with fragile X syndrome in their family histories are advised to seek genetic counseling to assess the likelihood of having children who are affected, and how severe any impairments may be in affected descendants.

Medication
Current trends in treating the disorder include medications for symptom-based treatments that aim to minimize the secondary characteristics associated with the disorder. If an individual is diagnosed with FXS, genetic counseling for testing family members at risk for carrying the full mutation or premutation is a critical first-step. Due to a higher prevalence of FXS in boys, the most commonly used medications are stimulants that target hyperactivity, impulsivity, and attentional problems. For co-morbid disorders with FXS, antidepressants such as selective serotonin reuptake inhibitors (SSRIs) are utilized to treat the underlying anxiety, obsessive-compulsive behaviors, and mood disorders. Following antidepressants, antipsychotics such as risperidone and quetiapine are used to treat high rates of self-injurious, aggressive and aberrant behaviors in this population (Bailey Jr et al., 2012). Anticonvulsants are another set of pharmacological treatments used to control seizures as well as mood swings in 13%–18% of individuals with FXS. Drugs targeting the mGluR5 (metabotropic glutamate receptors) that are linked with synaptic plasticity are especially beneficial for targeted symptoms of FXS. Lithium is also currently being used in clinical trials with humans, showing significant improvements in behavioral functioning, adaptive behavior, and verbal memory. Few studies suggested using folic acid, but more researches are needed due to the low quality of that evidence. Alongside pharmacological treatments, environmental influences such as home environment and parental abilities as well as behavioral interventions such as speech therapy, sensory integration, etc. all factor in together to promote adaptive functioning for individuals with FXS. While metformin may reduce body weight in persons with fragile X syndrome, it is uncertain whether it improves neurological or psychiatric symptoms.

Current pharmacological treatment centers on managing problem behaviors and psychiatric symptoms associated with FXS. However, as there has been very little research done in this specific population, the evidence to support the use of these medications in individuals with FXS is poor.

ADHD, which affects the majority of boys and 30% of girls with FXS, is frequently treated using stimulants. However, the use of stimulants in the fragile X population is associated with a greater frequency of adverse events including increased anxiety, irritability and mood lability. Anxiety, as well as mood and obsessive-compulsive symptoms, may be treated using SSRIs, although these can also aggravate hyperactivity and cause disinhibited behavior. Atypical antipsychotics can be used to stabilise mood and control aggression, especially in those with comorbid ASD. However, monitoring is required for metabolic side effects including weight gain and diabetes, as well as movement disorders related to extrapyramidal side effects such as tardive dyskinesia. Individuals with coexisting seizure disorder may require treatment with anticonvulsants.

Prognosis
A 2013 review stated that life expectancy for FXS was 12 years lower than the general population and that the causes of death were similar to those found for the general population.

Pharmacological therapy
Fragile X syndrome is the most "translated" human neurodevelopmental disorder under study. Hence, research into the etiology of FXS has given rise to many attempts at drug discovery. The increased understanding of the molecular mechanisms of disease in FXS has led to the development of therapies targeting the affected pathways. Evidence from mouse models shows that mGluR5 antagonists (blockers) can rescue dendritic spine abnormalities and seizures, as well as cognitive and behavioral problems, and may show promise in the treatment of FXS. Two new drugs, AFQ-056 (mavoglurant) and dipraglurant, as well as the repurposed drug fenobam are currently undergoing human trials for the treatment of FXS. There is also early evidence for the efficacy of arbaclofen, a GABAB agonist, in improving social withdrawal in individuals with FXS and ASD. In addition, there is evidence from mouse models that minocycline, an antibiotic used for the treatment of acne, rescues abnormalities of the dendrites. An open trial in humans has shown promising results, although there is currently no evidence from controlled trials to support its use.

History
In 1943, British neurologist James Purdon Martin and British geneticist Julia Bell described a pedigree of X-linked intellectual disability, without considering the macroorchidism (larger testicles). In 1969, Herbert Lubs first sighted an unusual "marker X chromosome" in association with intellectual disability. In 1970, Frederick Hecht coined the term "fragile site". And, in 1985, Felix F. de la Cruz outlined extensively the physical, psychological, and cytogenetic characteristics of those with the condition in addition to prospects for therapy. Continued advocacy later won him an honour through the FRAXA Research Foundation in December 1998.

title: Fragile X syndrome


text:
Nuclear explosive

A nuclear explosive is an explosive device that derives its energy from nuclear reactions. Almost all nuclear explosive devices that have been designed and produced are nuclear weapons intended for warfare.

Other, non-warfare, applications for nuclear explosives have occasionally been proposed. For example, nuclear pulse propulsion is a form of spacecraft propulsion that would use nuclear explosives to provide impulse to a spacecraft. A similar application is the proposal to use nuclear explosives for asteroid deflection. From 1958 to 1965 the United States government ran a project to design a nuclear explosive powered nuclear pulse rocket called Project Orion. Never built, this vessel would use repeated nuclear explosions to propel itself and was considered surprisingly practical. It is thought to be a feasible design for interstellar travel.

Nuclear explosives were once considered for use in large-scale excavation. A nuclear explosion could be used to create a harbor, or a mountain pass, or possibly large underground cavities for use as storage space. It was thought that detonating a nuclear explosive in oil-rich rock could make it possible to extract more from the deposit, e.g. note the Canadian Project Oilsand. From 1958 to 1973 the U.S. government exploded 28 nuclear test-shots in a project called Operation Plowshare. The purpose of the operation was to use peaceful nuclear explosions for moving and lifting enormous amounts of earth and rock during construction projects such as building reservoirs. The Soviet Union conducted a much more vigorous program of 122 nuclear tests, some with multiple devices, between 1965 and 1989 under the auspices of Program No. 7 – Nuclear Explosions for the National Economy.

As controlled nuclear fusion has proven difficult to use as an energy source, an alternate proposal for producing fusion power has been to detonate nuclear fusion explosives inside very large underground chambers and then using the heat produced, which would be absorbed by a molten salt coolant which would also absorb neutrons. The 1970s PACER (fusion) project investigated fusion detonation as a power source.

Failure to meet objectives, along with the realization of the dangers of nuclear fallout and other residual radioactivity, and with the enactment of various agreements such as the Partial Test Ban Treaty and the Outer Space Treaty, has led to the termination of most of these programs.

title: Nuclear explosive


text:
Multiple independently targetable reentry vehicle

A multiple independently targetable reentry vehicle (MIRV) is an exoatmospheric ballistic missile payload containing several warheads, each capable of being aimed to hit a different target. The concept is almost invariably associated with intercontinental ballistic missiles carrying thermonuclear warheads, even if not strictly being limited to them. An intermediate case is the multiple reentry vehicle (MRV) missile which carries several warheads which are dispersed but not individually aimed. All nuclear-weapon states except Pakistan and North Korea are currently confirmed to have deployed MIRV missile systems. Israel is suspected to possess or be in the process of developing MIRVs.

The first true MIRV design was the Minuteman III, first successfully tested in 1968 and introduced into actual use in 1970. The Minuteman III held three smaller W62 warheads, with yields of about 170 ktonTNT each in place of the single 1.2 MtonTNT W56 used on the Minuteman II. From 1970 to 1975, the United States would remove approximately 550 earlier versions of the Minuteman ICBM in the Strategic Air Command's (SAC) arsenal and replace them with the new Minuteman IIIs outfitted with a MIRV payload, increasing their overall effectiveness. The smaller power of the warheads used (W62, W78 and W87) was offset by increasing the accuracy of the system, allowing it to attack the same hard targets as the larger, less accurate, W56. The MMIII was introduced specifically to address the Soviet construction of an anti-ballistic missile (ABM) system around Moscow; MIRV allowed the US to overwhelm any conceivable ABM system without increasing the size of their own missile fleet. The Soviets responded by adding MIRV to their R-36 design, first with three warheads in 1975, and eventually up to ten in later versions. While the United States phased out the use of MIRVs in ICBMs in 2014 to comply with New START, Russia continues to develop new ICBM designs using the technology.

The introduction of MIRV led to a major change in the strategic balance. Previously, with one warhead per missile, it was conceivable that one could build a defense that used missiles to attack individual warheads. Any increase in missile fleet by the enemy could be countered by a similar increase in interceptors. With MIRV, a single new enemy missile meant that multiple interceptors would have to be built, meaning that it was much less expensive to increase the attack than the defense. This cost-exchange ratio was so heavily biased towards the attacker that the concept of mutual assured destruction became the leading concept in strategic planning and ABM systems were severely limited in the 1972 Anti-Ballistic Missile Treaty in order to avoid a massive arms race.

In June 2017 the United States finished converting its Minuteman III missiles back to using a single reentry vehicle system, as part of its obligations under the New START treaty.

Purpose
The military purpose of a MIRV is fourfold:
 * Enhance first-strike proficiency for strategic forces.
 * Providing greater target damage for a given thermonuclear weapon payload. Several small and lower yield warheads cause much more target damage area than a single warhead alone. This, in turn, reduces the number of missiles and launch facilities required for a given destruction level – much the same as the purpose of a cluster munition.
 * With single-warhead missiles, one missile must be launched for each target. By contrast, with a MIRV warhead, the post-boost (or bus) stage can dispense the warheads against multiple targets across a broad area.
 * Reduces the effectiveness of an anti-ballistic missile system that relies on intercepting individual warheads. While a MIRV attacking missile can have multiple warheads (312 on United States and Russian missiles, or 14 in a maximum payload shorter-range configuration of the Trident II now barred by START), interceptors may have only one warhead per missile. Thus, in both a military and an economic sense, MIRVs render ABM systems less effective, as the costs of maintaining a workable defense against MIRVs would greatly increase, requiring multiple defensive missiles for each offensive one. Decoy re-entry vehicles can be used alongside actual warheads to minimize the chances of the actual warheads being intercepted before they reach their targets. A system that destroys the missile earlier in its trajectory (before MIRV separation) is not affected by this but is more difficult, and thus more expensive to implement.

MIRV land-based ICBMs were considered destabilizing because they tended to put a premium on striking first. The world's first MIRV—US Minuteman III missile of 1970—threatened to rapidly increase the US's deployable nuclear arsenal and thus the possibility that it would have enough bombs to destroy virtually all of the Soviet Union's nuclear weapons and negate any significant retaliation. Later on the US feared the Soviet's MIRVs because Soviet missiles had a greater throw-weight and could thus put more warheads on each missile than the US could. For example, the US MIRVs might have increased their warhead per missile count by a factor of 6 while the Soviets increased theirs by a factor of 10. Furthermore, the US had a much smaller proportion of its nuclear arsenal in ICBMs than the Soviets. Bombers could not be outfitted with MIRVs so their capacity would not be multiplied. Thus the US did not seem to have as much potential for MIRV usage as the Soviets. However, the US had a larger number of submarine-launched ballistic missiles, which could be outfitted with MIRVs, and helped offset the ICBM disadvantage. It is because of their first-strike capability that land-based MIRVs were banned under the START II agreement. START II was ratified by the Russian Duma on 14 April 2000, but Russia withdrew from the treaty in 2002 after the US withdrew from the ABM treaty.

Operation
In a MIRV, the main rocket motor (or booster) pushes a "bus" into a free-flight suborbital ballistic flight path. After the boost phase, the bus maneuvers using small on-board rocket motors and a computerized inertial guidance system. It takes up a ballistic trajectory that will deliver a re-entry vehicle containing a warhead to a target and then releases a warhead on that trajectory. It then maneuvers to a different trajectory, releasing another warhead, and repeats the process for all warheads.

[[Image:Minuteman III MIRV path.svg|thumb|upright=1.5|[[LGM-30 Minuteman|Minuteman III]] MIRV launch sequence:

1. The missile launches out of its silo by firing its first-stage boost motor (A). 2. About 60 seconds after launch, the first-stage drops off and the second-stage motor (B) ignites. The missile shroud (E) is ejected. 3. About 120 seconds after launch, the third-stage motor (C) ignites and separates from the second-stage. 4. About 180 seconds after launch, the third-stage thrust terminates and the post-boost vehicle (D) separates from the rocket. 5. The post-boost vehicle maneuvers itself and prepares for re-entry vehicle (RV) deployment. 6. While the post-boost vehicle backs away, the RVs, decoys, and chaff are deployed (this may occur during ascent). 7. The RVs and chaff reenter the atmosphere at high speeds and are armed in flight. 8. The nuclear warheads detonate, either as air bursts or ground bursts.]]

The precise technical details are closely guarded military secrets, to hinder any development of enemy counter-measures. The bus's on-board propellant limits the distances between targets of individual warheads to perhaps a few hundred kilometers. Some warheads may use small hypersonic airfoils during the descent to gain additional cross-range distance. Additionally, some buses (e.g. the British Chevaline system) can release decoys to confuse interception devices and radars, such as aluminized balloons or electronic noisemakers.

Accuracy is crucial because doubling the accuracy decreases the needed warhead energy by a factor of four for radiation damage and by a factor of eight for blast damage. Navigation system accuracy and the available geophysical information limits the warhead target accuracy. Some writers believe that government-supported geophysical mapping initiatives and ocean satellite altitude systems such as Seasat may have a covert purpose to map mass concentrations and determine local gravity anomalies, in order to improve accuracies of ballistic missiles. Accuracy is expressed as circular error probable (CEP). This is the radius of the circle that the warhead has a 50 percent chance of falling into when aimed at the center. CEP is about 90–100 m for the Trident II and Peacekeeper missiles.

MRV
A multiple re-entry vehicle (MRV) system for a ballistic missile deploys multiple warheads above a single aimpoint which then drift apart, producing a cluster bomb-like effect. These warheads are not individually targetable. The advantage of an MRV over a single warhead is the increased effectiveness due to the greater coverage; this increases the overall damage produced within the center of the pattern, making it far greater than the damage possible from any single warhead in the MRV cluster; this makes for an efficient area-attack weapon and makes interception by anti-ballistic missiles more challenging due to the number of warheads being deployed at once.

Improved warhead designs allow smaller warheads for a given yield, while better electronics and guidance systems allow greater accuracy. As a result, MIRV technology has proven more attractive than MRV for advanced nations. Multiple-warhead missiles require both a miniaturized physics package and a lower mass re-entry vehicle, both of which are highly advanced technologies. As a result, single-warhead missiles are more attractive for nations with less advanced or less productive nuclear technology. The United States first deployed MRV warheads on the Polaris A-3 SLBM in 1964 on the USS Daniel Webster. The Polaris A-3 missile carried three warheads each having an approximate yield of 200 ktTNT. This system was also used by the Royal Navy who also retained MRV with the Chevaline upgrade, though the number of warheads in Chevaline was reduced to two due to the ABM counter-measures carried. The Soviet Union deployed 3 MRVs on the R-27U SLBM and 3 MRVs on the R-36P ICBM. Refer to atmospheric re-entry for more details.

MIRV-capable missiles

 * China:
 * DF-3A (retired, 3 warheads)
 * DF-4A (retired, 3 warheads)
 * DF-5B (active, 3-8 warheads)
 * DF-5C (active, 10 warheads)
 * DF-31A (active, 3-5 warheads)
 * DF-31B (active, 3-5 warheads)
 * DF-41 (active, up to 10 warheads)
 * JL-2 (active, 1-3 warheads)
 * JL-3 (under development)

 * France:
 * M4 (retired, 6 warheads)
 * M45 (retired, 6 warheads)
 * M51 (active, 6-10 warheads)

 * India
 * Agni-V (active, 3-6 (tested) 10–12 (Operational) nuclear warheads)
 * Agni Prime (active, 2 warheads)
 * Agni-VI (under development)
 * K-6 (under development)

 * Israel:
 * Jericho 3 (active, suspected capability, not announced, 2-3 technically possible)

 * Pakistan:
 * Ababeel (active, 3-8 warheads)

 * USSR/Russian Federation:
 * R-36 mod 4 (retired, 10-14 warheads)
 * R-36 mod 5 (active, 10 warheads)
 * R-29R (active, 3 warheads)
 * R-29RK (retired, 7 warheads)
 * MR-UR-100 Sotka (retired, 4 warheads)
 * UR-100N mod 3 (retired, 6 warheads)
 * RSD-10 Pioneer (retired, 3 warheads)
 * R-39 Rif (retired, 10 warheads)
 * R-29RM Shtil (retired, 4 warheads)
 * RT-23 Molodets (retired, 10 warheads)
 * R-29RMU Sineva (active, 4 or 10 warheads)
 * RS-24 Yars (active, 3-4 warheads)
 * R-29RMU2 Layner (active, 4 or 12 warheads)
 * RSM-56 Bulava (active 6-10 warheads)
 * RS-28 Sarmat (active, 10-15 warheads)
 * RS-26 Rubezh (development stopped, 4 warheads)
 * BZhRK Barguzin (development stopped, 4-16 warheads)

 * United Kingdom:
 * UGM-133 Trident II (active, 8-14 warheads)

 * United States:
 * LGM-30 Minuteman III (active, 1-3 warheads, currently carries one warhead)
 * UGM-73 Poseidon (retired, 10 or 14 warheads)
 * UGM-96 Trident I (retired, 8 warheads)
 * LGM-118 Peacekeeper (retired, 10 warheads)
 * UGM-133 Trident II (active 8-14 warheads)


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Naval ship

A naval ship (or naval vessel) is a military ship (or sometimes boat, depending on classification) used by a navy. Naval ships are differentiated from civilian ships by construction and purpose. Generally, naval ships are damage resilient and armed with weapon systems, though armament on troop transports is light or non-existent.

Naval ships designed primarily for naval warfare are termed warships, as opposed to support (auxiliary ships) or shipyard operations.

Naval ship classification
Naval ship classification is a field that has changed over time, and is not an area of wide international agreement, so this article currently uses the system as currently used by the United States Navy.

 * Aircraft carrier – ships that serve as mobile seaborne airfields, designed primarily for the purpose of conducting combat operations by Carrier-based aircraft which engage in attacks against airborne, surface, sub-surface and shore targets.
 * Surface combatant – large, heavily armed surface ships which are designed primarily to engage enemy forces on the high seas, including various types of battleship, battlecruiser, cruiser, destroyer, frigate, and corvette.
 * Submarine – self-propelled submersible types regardless of whether they are employed as combatant, auxiliary, or research and development vehicles which have at least a residual combat capability.
 * Patrol combatant – combatants whose mission may extend beyond coastal duties and whose characteristics include adequate endurance and sea keeping providing a capability for operations exceeding 48 hours on the high seas without support.
 * Amphibious warfare – ships having organic capability for amphibious assault and which have characteristics enabling long duration operations on the high seas.
 * Combat logistics – ships that have the capability to provide underway replenishment to fleet units.
 * Mine warfare – ships whose primary function is mine warfare on the high seas.
 * Coastal defense – ships whose primary function is coastal patrol and interdiction.
 * Sealift – ships that have the capability to provide direct material support to other deployed units operating far from home base.
 * Support – ships, such as oilers and auxiliary ships designed to operate in the open ocean in a variety of sea states to provide general support to either combatant forces or shore based establishments. (Includes smaller auxiliaries which, by the nature of their duties, leave inshore waters).
 * Service type craft – navy-subordinated craft (including non-self-propelled) designed to provide general support to either combatant forces or shore-based establishments.

Size
In rough order of tonnage (largest to smallest), modern surface naval ships are commonly divided into the following different classes. The larger ships in the list can also be classed as capital ships.
 * Aircraft carrier
 * Helicopter carrier
 * Amphibious assault ship
 * Stealth ship
 * Battleship
 * Battlecruiser
 * Heavy cruiser
 * Light cruiser
 * Destroyer
 * Frigate
 * Corvette
 * Patrol boat
 * Fast attack craft

Some classes above may now be considered obsolete as no ships matching the class are in current service. There is also much blurring and gray areas between the classes, depending on their intended use, history, and interpretation of the class by different navies.

Auxiliary ships
Navies also use auxiliary ships for transport and other non-combat purposes. They are classified by different names according to their roles:
 * Ammunition ships are ships to transport and replenish ammunition for warships and naval aircraft.
 * Barracks ships are ships or barges for temporary accommodation for sailors, soldiers and other military personnel.
 * Colliers were ships used to transport and replenish coal for warships during the Age of Steam.
 * Command ships are the flagship of the commander of a fleet.
 * Combat stores ships are ships to transport supplies and replenish ships in the high seas.
 * Depot ships are ships used as mobile or fixed bases for destroyers, fast attack craft, minesweepers, submarines, patrol vessels, landing craft and other small ships.
 * Fast combat support ships are a type of auxiliary ships designed with high speed to keep up with the carrier battle group/carrier strike group, while the multi-product station is capable of supplying all types of necessities for the fleet.
 * Hospital ships are ships functioning as floating hospitals and are used to provide medical treatment in the high seas. The Second Geneva Convention prohibits military attacks on hospital ships that meet specified requirements, though belligerent forces have right of inspection and may take patients, but not staff, as prisoners of war.
 * Repair ships are ships to provide maintenance and repairs to warships.
 * Aircraft repair ships are repair vessels to provide maintenance and repairs to naval aircraft.
 * Rescue and salvage ships are ships to aid stricken vessels.
 * Submarine rescue ships are used for submarine rescue and deep sea salvage operations.
 * Research ships are ships to research military concerns, such as sonar or weapons trails.
 * Replenishment oilers are ships to transport oil and refuel ships in the high seas.
 * Spy ships are dedicated ships to collect intelligence.
 * Survey ship is any type of ship or boat that is used for underwater surveys.
 * Ship's tender is a type of ship used to serve other boats, submarines, ships or seaplanes.
 * Destroyer tender
 * Submarine tender
 * Torpedo boat tender
 * Motor torpedo boat tender
 * Seaplane tender
 * Troopships are ships, usually repurposed passenger ships used to transport marines and soldiers.
 * Training ship are ships to train students into sailors. Sail training ships are used to provide an unconventional and effective way of building many useful skills on and off the water.
 * Torpedo trials craft are ships used by navies for the development of new naval torpedoes and during practice firings. These craft are designed to track and monitor, locate and retrieve the spent torpedo for analysis and refurbishment for reuse.
 * Tracking ships are a type of ship fitted with antennas and electronics to support the launching and tracking of rockets and missiles.

title: Naval ship