A chemical weapon
) is a specialized munition
that uses chemicals formulated
to inflict death or harm on humans. According to the Organisation for the Prohibition of Chemical Weapons
(OPCW), "the term chemical weapon may also be applied to any toxic chemical or its precursor
that can cause death, injury, temporary incapacitation or sensory irritation through its chemical action. Munitions or other delivery devices designed to deliver chemical weapons, whether filled or unfilled, are also considered weapons themselves."
Chemical weapons are classified as weapons of mass destruction (WMD), though they are distinct from nuclear weapons, biological weapons, and radiological weapons. All may be used in warfare and are known by the military acronym NBC (for nuclear, biological, and chemical warfare). Weapons of mass destruction are distinct from conventional weapons, which are primarily effective due to their explosive, kinetic, or incendiary potential. Chemical weapons can be widely dispersed in gas, liquid and solid forms, and may easily afflict others than the intended targets. Nerve gas, tear gas and pepper spray are three modern examples of chemical weapons.
Lethal unitary chemical agents and munitions are extremely volatile and they constitute a class of hazardous chemical weapons that have been stockpiled by many nations. Unitary agents are effective on their own and do not require mixing with other agents. The most dangerous of these are nerve agents (GA, GB, GD, and VX) and vesicant (blister) agents, which include formulations of sulfur mustard such as H, HT, and HD. They all are liquids at normal room temperature, but become gaseous when released. Widely used during the First World War, the effects of so-called mustard gas, phosgene gas and others caused lung searing, blindness, death and maiming.
The Nazi Germans during World War II committed genocide (mainly against Jews but including other targeted populations) using a commercial hydrogen cyanide blood agent trade-named Zyklon B. Discharging it in large gas chambers was the preferred method to efficiently murder their victims in a continuing industrial fashion. The Holocaust resulted in the largest death toll to chemical weapons in history.
As of 2016CS gas and pepper spray remain in common use for policing and riot control; while CS is considered a non-lethal weapon, pepper spray is known for its lethal potential. Under the Chemical Weapons Convention (1993), there is a legally binding, worldwide ban on the production, stockpiling, and use of chemical weapons and their precursors. Notwithstanding, large stockpiles of chemical weapons continue to exist, usually justified as a precaution against putative use by an aggressor.
Chemical warfare involves using the toxic properties of chemical substances as weapons. This type of warfare is distinct from nuclear warfare and biological warfare, which together make up NBC, the military initialism for Nuclear, Biological, and Chemical (warfare or weapons). None of these fall under the term conventional weapons, which are primarily effective because of their destructive potential. Chemical warfare does not depend upon explosive force to achieve an objective. It depends upon the unique properties of the chemical agent weaponized.
A British gas bomb that was used during World War I.
A lethal agent is designed to injure, incapacitate, or kill an opposing force, or deny unhindered use of a particular area of terrain. Defoliants are used to quickly kill vegetation and deny its use for cover and concealment. Chemical warfare can also be used against agriculture and livestock to promote hunger and starvation. Chemical payloads can be delivered by remote controlled container release, aircraft, or rocket. Protection against chemical weapons includes proper equipment, training, and decontamination measures.
John Singer Sargent
's iconic World War I painting: Gassed
, showing blind casualties on a battlefield after a mustard gas attack
Simple chemical weapons were used sporadically throughout antiquity and into the Industrial age. It was not until the 19th century that the modern conception of chemical warfare emerged, as various scientists and nations proposed the use of asphyxiating or poisonous gasses. So alarmed were nations that multiple international treaties, discussed below, were passed – banning chemical weapons. This however did not prevent the extensive use of chemical weapons in World War I. The development of chlorine gas, among others, was used by both sides to try to break the stalemate of trench warfare. Though largely ineffective over the long run, it decidedly changed the nature of the war. In many cases the gasses used did not kill, but instead horribly maimed, injured, or disfigured casualties. Some 1.3 million gas casualties were recorded, which may have included up to 260,000 civilian casualties.
The interwar years saw occasional use of chemical weapons, mainly to put down rebellions. In Nazi Germany, much research went into developing new chemical weapons, such as potent nerve agents. However, chemical weapons saw little battlefield use in World War II. Both sides were prepared to use such weapons, but the Allied powers never did, and the Axis used them only very sparingly. The reason for the lack of use by the Nazis, despite the considerable efforts that had gone into developing new varieties, might have been a lack of technical ability or fears that the Allies would retaliate with their own chemical weapons. Those fears were not unfounded: the Allies made comprehensive plans for defensive and retaliatory use of chemical weapons, and stockpiled large quantities. Japanese forces used them more widely, though only against their Asian enemies, as they also feared that using it on Western powers would result in retaliation. Chemical weapons were frequently used against Kuomintang and Chinese communist troops. However, the Nazis did extensively use poison gas against civilians in The Holocaust. Vast quantities of Zyklon B gas and carbon monoxide were used in the gas chambers of Nazi extermination camps, resulting in the overwhelming majority of some three million deaths. This remains the deadliest use of poison gas in history.
The post-war era has seen limited, though devastating, use of chemical weapons. Some 100,000 Iranian troops were casualties of Iraqi chemical weapons during the Iran–Iraq War. Iraq used mustard gas and nerve agents against its own civilians in the 1988 Halabja chemical attack. The Cuban intervention in Angola saw limited use of organophosphates. The Syrian government has used sarin, chlorine, and mustard gas in the Syrian civil war – generally against civilians. Terrorist groups have also used chemical weapons, notably in the Tokyo subway sarin attack and the Matsumoto incident. See also chemical terrorism.
Before the Second World War
International law has prohibited the use of chemical weapons since 1899, under the Hague Convention: Article 23 of the Regulations Respecting the Laws and Customs of War on Land adopted by the First Hague Conference "especially" prohibited employing "poison and poisoned arms". A separate declaration stated that in any war between signatory powers, the parties would abstain from using projectiles "the object of which is the diffusion of asphyxiating or deleterious gases".
The Washington Naval Treaty, signed February 6, 1922, also known as the Five-Power Treaty, aimed at banning chemical warfare but did not succeed because France rejected it. The subsequent failure to include chemical warfare has contributed to the resultant increase in stockpiles.
The Geneva Protocol, officially known as the Protocol for the Prohibition of the Use in War of Asphyxiating, Poisonous or other Gases, and of Bacteriological Methods of Warfare, is an International treaty prohibiting the use of chemical and biological weapons. It was signed at Geneva June 17, 1925, and entered into force on February 8, 1928. 133 nations are listed as state parties to the treaty. Ukraine is the newest signatory; acceding August 7, 2003.
This treaty states that chemical and biological weapons are "justly condemned by the general opinion of the civilised world". And while the treaty prohibits the use of chemical and biological weapons, it does not address the production, storage, or transfer of these weapons. Treaties that followed the Geneva Protocol did address those omissions and have been enacted.
The 1993 Chemical Weapons Convention (CWC) is the most recent arms control agreement with the force of International law. Its full name is the Convention on the Prohibition of the Development, Production, Stockpiling and Use of Chemical Weapons and on their Destruction. That agreement outlaws the production, stockpiling and use of chemical weapons. It is administered by the Organisation for the Prohibition of Chemical Weapons (OPCW), which is an independent organization based in The Hague.
The OPCW administers the terms of the CWC to 192 signatories, which represents 98% of the global population. As of June 2016 The OPCW has conducted 6,327 inspections at 235 chemical weapon-related sites and 2,255 industrial sites. These inspections have affected the sovereign territory of 86 States Parties since April 1997. Worldwide, 4,732 industrial facilities are subject to inspection under provisions of the CWC.
, 66,368 of 72,525 metric tonnes, (92% of chemical weapon stockpiles), have been verified as destroyed.