A chemical weapon (CW) is a device that uses chemicals formulated to inflict death or harm to human beings. They may be classified as weapons of mass destruction though are separate from biological weapons (diseases), nuclear weapons and radiological weapons (which use radioactive decay of elements). Chemical weapons can be widely dispersed in gas, liquid and solid forms and may easily afflict others than the intended targets. Nerve gas and tear gas are two modern examples.
Lethal unitary chemical agents and munitions are extremely volatile and constitute a class of hazardous chemical weapons stockpiled by many nations. (Unitary agents are effective on their own and require no mixing with other agents.) The most dangerous of these are nerve agents GA, GB, and VX, and vesicant (blister) agents which are formulations of sulfur mustard such as H, HT, and HD. 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.
Under the Chemical Weapons Convention (1993), there is a legally binding world-wide ban on the production, stockpiling, and use of chemical weapons and their precursors. Notwithstanding, large stockpiles thereof continue to exist, usually only as a precaution against putative use by an aggressor
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";also, 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 CW—but did not succeed because the French rejected it. The subsequent failure to include CW 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 acceded August 7, 2003 and is the most recent member nation. This treaty states that chemical and biological weapons are "justly condemned by the general opinion of the civilised world." While the treaty prohibits the use of chemical and biological weapons, it does not address the production, storage, or transfer of these weapons. Later treaties would address these omissions and have been enacted.
