Chemical Weapons

Chemical Weapons

Chemical weapons use the toxic properties of chemical substances  to produce physical or physiological effects. Thus any  chemical used in warfare is called a Chemical Weapon Agent (CWA)

These chemicals could come in liquid, gas or solid form and blister.

The different types of chemical weapons are  classified according to their effect on the organism (lethal and incapacitating categories). These types are:

  • Nerve Agents
  • Mustard Agents
  • Hydrogen Cyanide
  • Tear Gases
  • Arsines
  • Psychotomimetic Agents
  • Toxins
  • Potential CW Agents.


The origins of the studies and lore of chemical weapons began in World War I when an aerosol was used during the battles. Given the more frequent use that these weapons began to have in 1925 the Geneva Protocol was signed prohibiting use of chemical weapons in warfare

Chemical weapons also were employed in the intervening period by Italy (in Ethiopia) and Japan (in Manchuria and China). Both nations were signatories to the Geneva Convention.

Despite Chemical weapons were never deliberately employed by the Allies or the Axis during World War II, despite the accumulation of enormous stockpiles by both sides. Instances of employment of chemical weapons in the local wars since then are arguable, although they were definitely used in the Iran-Iraq conflict of 1982–87.

Development of chemical weapons in World War I was predominantly the adaptation of a chemical “fill” to a standard munition. The chemicals were commercial chemicals or variants. Their properties were, for the most part, well known. The Germans simply opened canisters of chlorine and let the prevailing winds do the dissemination. Shortly thereafter the French put phosgene in a projectile and this method became the principal means of delivery. In July 1917, the Germans employed mustard shells for the first time and simultaneously attempted to use a solid particulate emetic, diphenyl chloroarsine, as a mask breaker. Mustard, an insidious material, penetrates leather and fabrics and inflicts painful burns on the skin.

These two themes, along with significant increases in toxicity, represent a large segment of the research and development of chemical weapons that nations have pursued over the years. There is first the concept of agents that attack the body through the skin, preferably also through clothing, and more preferably through protective clothing. Along with that concept is the idea of penetrating or "breaking" the protective mask so that it no longer offers protection for the respiratory system. Increasing the toxicity of the chemical agent used would theoretically lower the amounts required to produce a battlefield effect. Unless this increase is significant, however, it can be masked by the inefficiencies of disseminating the agent. Consequently, later development has focused on the methods for delivering the agent efficiently to the target.

The chemicals employed before World War II can be styled as the “classic” chemical weapons. They are relatively simple substances, most of which were either common industrial chemicals or their derivatives. An example is phosgene, a choking agent (irritates the eyes and respiratory tract). Phosgene is important in industry as a chlorinating material. A second example is hydrogen cyanide, a so-called blood agent (prevents transfer of oxygen to the tissues), now used worldwide in the manufacture of acrylic polymers. The classic chemical agents would be only marginally useful in modern warfare and generally only against an unsophisticated opponent. Moreover, large quantities would be required to produce militarily significant effects, thus complicating logistics.

Blister agents or vesicants are an exception to the limited utility of classic agents. Although these materials have a relatively low lethality, they are effective casualty agents that inflict painful burns and blisters requiring medical attention even at low doses. The classic mustard is the most popular among proliferant nations since it is relatively easy to make. Mustard is generally referred to as the “king” of agents because of its ease of production, low cost, predictable properties, persistence, and ability to cause resource-devouring casualties rather than fatalities. Its insidious nature is both an advantage and a disadvantage. Mustard on the skin causes no immediate sensation and symptoms normally do not appear until several hours after exposure. At incapacitating levels this may be as long as 12 hours. (Contrary to the normal expectation, horrible fatalities occurred in the Iran-Iraq War because Iranian soldiers, feeling no effects, continued to wear mustard soaked clothing and inhale its fumes.)

To produce immediate effects, an arsenical vesicant known as lewisite was developed in the United States. Much of the former Soviet Union vesicant stocks were mixtures of lewisite and sulfur mustard. Between the world wars the development of chemical weapons included adaptation to aircraft delivery (bombs) and exploitation of lewisite, since the more potent mustard was, from a battlefield perspective, slow in producing casualties. Independent experiments in several countries led them to consider/adopt mixtures of mustard and lewisite as fills for chemical munitions.

The Italians, Hungarians, Japanese, French, English, Russians, and Americans, as well as the Germans, all perfected mustard, phosgene, and similar agents during World War II. Although never used in the conflict, these nations amassed such huge quantities of chemical munitions that their disposal presented a practical problem, one that would be virtually insurmountable in today’s more environmentally conscious world. In those more naive times, however, the munitions simply found their way to the bottoms of almost all the world’s oceans in the holds of expendable ships.

We see language addressing chemical agents in an international declaration for the first time in the 1899 Hague Declaration. This declaration prohibited using projectiles with "asphyxiating and deleterious gases." The 1907 Hague Convention also prohibited the use in war of poisonous substances. Despite this modern chemical warfare began during World War I. The Germans were the first to use these weapons by releasing tons of chlorine gas upwind from Allied soldiers. Later in the war the French attached phosgene gas containers to artillery munitions. This became the standard way of constructing chemical weapons for years; simply place containers of a dangerous chemical agent in traditional munitions. The war raised public concern across Europe about the costs of chemical weapons after World War I and language restricting their manufacture in Germany was included in the Treaty of Versailles.

The fear of chemical warfare gave momentum to the Geneva Protocol which was signed in June 17, 1925 and came into force February 8, 1928. This treaty prevented the use of “asphyxiating gas, or any other kind of gas, liquids, substances or similar materials.” The treaty languished in Congress in the United States until ratification in 1975.

World War II saw further development on chemical weapons. German Scientists discovered nerve agents, the famous being sarin, but did not use them for fear of a chemical weapons retaliation by the Allies. The most famous case of chemical weapons use during the war occurred in the concentration camps in Nazi Germany.

Chemical weapons continued to be viewed with caution during the Cold War. Despite deterrence stopping the U.S. and the U.S.S.R. from using chemical weapons against each other, Iraq openly used chemical weapons against Iran. Approximately 100,000 Iranian soldiers were attacked with chemical weapons, mostly with mustard gas. Estimates of civilian casualties and effects are unknown. International apathy to the regime in Tehran meant that Iraq suffered few international consequences for its use of chemical weapons in the conflict.

Despite few major uses of chemical agents a stronger international treaty regarding chemical weapons was formulated right after the Cold War. However the Soviet Union and the United States signed a bilateral treaty in 1990 to destroy their stockpiles of chemical weapons which had grown but had not been used during the Cold War. In 1993 the Chemical Weapons Convention (CWC) was signed and came into effect in 1997.

  •  Chemical Weapons Convention
In 1992  the Conference on Disarmament agreed to the text of the Chemical Weapons Convention (CWC). In the same year the Convention  was  adopted by the General Assembly at its forty-seventh session  in its resolution entitled Convention on the Prohibition of the Development, Production, Stockpiling and Use of Chemical Weapons and on Their Destruction (See text of the Convention). The CWC opened for signature  on 13 January 1993 and entered into force in 1997. 

The CWC allows for the  verification of compliance by State Parties. 

ENTRY INTO FORCE:  29 April 1997
DEPOSITARY: Secretary-General of the UN

The Convention prohibits all development, production, acquisition, stockpiling, transfer, and use of chemical weapons. It requires each State Party to destroy chemical weapons and chemical weapons production facilities it possesses, as well as any chemical weapons it may have abandoned on the territory of another State Party. The verification provisions of the CWC not only affect the military sector but also the civilian chemical industry, world-wide, through certain restrictions and obligations regarding the production, processing and consumption of chemicals that are considered relevant to the objectives of the Convention. They will be verified through a combination of reporting requirements, routine on-site inspections of declared sites and short-notice challenge inspections. The Convention also contains provisions on assistance in case a State Party is attacked or threatened with attack by chemical weapons and on promoting the trade in chemicals and related equipment among States Parties.

States are required to enact penal legislation, prohibiting their private citizens, no matter where they are on earth, from undertaking any of the activities prohibited to the state itself by the Convention. Many states have also enacted laws laying down an obligation to provide declaration required relating to production, processing, consumption, import and export of chemicals above thresholds specified in the Convention.

Click here for the Action Plan on Implementation of the CWC, adopted October 2003.

Another area in which most states have enacted legislation provides two-year, multiple-entry visa to inspectors who on 48 hours notification can inspect to clarify and resolve questions of non-compliance. During inspections they can interview personnel, request samples and evaluate chemical weapons destruction sites. They can evaluate a site for up to 84 hours.

The CWC also created the scheduling scheme now used to classify how dangerous chemical agents are.

Schedule 1: These chemicals have few, if any, legitimate uses. They may be produced or used only for research, medical, pharmaceutical or protective purposes. Almost all nerve agents fall under this schedule.

Schedule 2: Again, like schedule 1 substances, these chemicals have no large-scale industrial application but do have legitimate small-scale use. Dimethyl methylphosphonate, a precursor to sarin, can also be used as a flame retardant is a good example of a schedule 2 chemical.

Schedule 3: Unlike the first two schedules, these chemicals do have large-scale industrial use. Any plant producing more than 30 tons a year of schedule 3 chemicals must notify and can be inspected by the OPCW.


  •  Organization for the prohibition of Chemical Weapons (OPCW)

The OPCW was established with the responsibility to prepare detailed operation procedures and to put into place the necessary infrastructure for the permanent implementing agency provided for in the Convention.   With the entry-into-force of the Convention in 1997, the OPCW was formally established.

The OPCW is mandated to ensure the implementation of its provisions, including those for international verification of compliance with it, and to provide a forum for consultation and cooperation among States Parties.

The Organisation for the Prohibition of Chemical Weapons (OPCW) is the implementing body of the Chemical Weapons Convention (CWC or Convention). The OPCW is given the mandate to achieve the object and purpose of the Convention, to ensure the implementation of its provisions, including those for international verification of compliance with it, and to provide a forum for consultation and cooperation among States Parties.

The Technical Secretariat of the OPCW is responsible for the day-to-day administration and implementation of the Convention, including inspections, while the Executive Council and the Conference of the States Parties are decision-making organs designed primarily to determine questions of policy and resolve matters arising between the States Parties on technical issues or on interpretations of the Convention. The chairs of the Executive Council and the Conference are appointed by each body's membership. The Technical Secretariat is headed by a Director-General, who is appointed by the Conference on the recommendation of the Council.

Member States

The OPCW Member States already represent about 98% of the global population and landmass, as well as 98% of the worldwide chemical industry. A state becomes a State Party, and thereby a member of the Organisation, by one of three means — ratification, accession or succession. Instruments of ratification, accession or succession must be deposited with the designated Depositary of the Convention, who is the Secretary-General of the United Nations.

Non-Member States
List of Signatory States which have not yet ratified the Chemical Weapons Convention, and a list of States that have neither signed nor acceded to the Chemical Weapons Convention. The OPCW provides all States not Party to the CWC support in preparing to join the CWC and to effectively implement the global ban on chemical weapons.

Conference of the States Parties
The Conference of the States Parties is the main policy-making organ of the OPCW. Composed of all Member States, the Conference meets annually as well as in special session when necessary.

Elected for two years (2000-2002): Austria, Canada, Netherlands, Spain, Sweden, Chile, Cuba, Panama, Peru, Poland, Russian Federation, Slovenia, Indonesia, Islamic Republic of Iran, Pakistan, Sri Lanka, Algeria, Morocco, Namibia and South Africa.

Elected for two years (1999- 2001): France, Germany, Italy, UK, Northern Ireland, US, Argentina, Brazil, Mexico, Romania, Ukraine, Bangladesh, China, India, Japan, Republic of Korea, Saudi Arabia, Cameroon, Cote d'Ivoire, Ethiopia, Tunisia, and Zimbabwe.

Chemical Weapons Convention and the Current Issues

The key element in the CWC was a plan for the destruction of the world’s known chemical weapon stockpiles. The treaty was non-discriminatory and treated all signatories equally. States who sign must declare their chemical stockpiles and thereafter destroy them. The plan was composed of four phases leading ultimately to the destruction of all known chemical weapons.

Phase %Reduction Deadline Notes
II20%2002Complete destruction of empty munitions, precursor chemicals, filling equipment and weapons systems
IV100%2007No extensions permitted past April 2012

The implementation of the CWC has been slow and the U.S. and Russia do not intend on finishing elimination of their stockpiles well past 2012. However 100% of the declared chemical weapons production facilities have been inactivated and roughly 19% of the world's declared stockpile of approximately 70,000 metric tons of chemical agent have been verifiably destroyed. In addition 178 nations, representing about 95% of the global population, have signed the CWC and joined the Organisation for the Prohibition of Chemical Weapons (OPCW), the international institution that oversees implementation of the CWC and is based in the Hague.

The most recent comprehensive look at the state of chemical weapons is "Weapons of Terror: Freeing the World of Nuclear, Biological, and Chemical." This is the report Hans Blix presented to the UN on June 1, 2006 and can be found online at The report contains many recommendations from the commission numbers 37 through 42 of which deal with chemical weapons. The thrust of the recommendations is the need to allocate adequate resources at the state and international levels (through the OPCW) to insure implementation of the CWC.

Today the main fear is not the use by a state where the deterrent fear of a retaliatory attack provides incentives for non-use but that chemical weapons will fall into the hands of terrorists or other non-state actors. The fear of "chemical terrorists" became a reality when in 1994 the Aum Shinrikyo Japanese sect used sarin in the 1994 Matsumoto attack and subsequent attacks in Tokyo subways in 1995. This group had substantial financial backing as well as technical expertise and still had problems with purity and producing large quantities of chemical agents. Much more likely is an attack on a chemical plant or transport vehicle. The severity of this threat is apparent from past chemical plant accidents. In Bhopal, India over 3,000 people died when an accidental release of gas from a pesticide plant occured in 1984.

Conventions, Laws, and Agreements relating to chemical warfare and chemical weapons

* The Geneva Protocol for the Prohibition of the Use in War of Asphyxiating, Poisonous or Other Gases, and of Bacteriological Methods of Warfare.

* The Biological and Toxin Weapons Convention, Convention on the Prohibition of the Development, Production and Stockpiling of Bacteriological (Biological) and Toxin Weapons.

* The Australian Group: Formed by Australia in 1984 this 30 member group is an informal and voluntary consortium of nations, founded as a result of chemical weapons use in the Iran-Iraq War, whose goal is the limitation of chemical and biological weapons proliferation. Members meet annually to share information about proliferation dangers and to harmonize national export controls in an effort to curb the transfer of materials or equipment that could be used in the creation of chemical or biological weapons. The group has created lists of both items whose export should be controlled, as well as "warning" lists of items whose purchase could be indicative of proliferation activities. With no formal charter or constitution, the Australia Group works by consensus.

* Convention (II) with Respect to the Laws and Customs of War on Land, The Hague 1899 (see Article 23 (a) of the Annex).

* Convention (II) with Respect to the Laws and Customs of War on Land, The Hague 1907 (see Article 23 (a) of the Annex). Some Conventions relating to Toxic Chemicals and the Environment

* Basel Convention on the Control of Transboundary Movement of Hazardous Wastes and the Disposal.

* ENMOD, Convention on the Prohibition of Military or Any Other Hostile Use of Environmental Modification Techniques.

* Bamako Convention the Ban of the Import Into Africa and the Control of Transboundary Movement and Management of Hazardous Wastes Within Africa.

* Convention for the CO-operation in the Protection and Development of the Marine and Coastal Environment of the West and Central African Region (1981); and Protocol.

* Vienna Convention for the Protection of the Ozone Layer (1985) and the Corresponding Protocol: Montreal Protocol on Substances That Deplete the Ozone Layer.

* Convention on the Prevention of Marine Pollution from Land-Based Sources (1974).

* Convention on the Protection of the Mediterranean Sea Against Pollution (1976) and Protocols (1980, 1982).

* Agreement for CO-operation in Dealing with Pollution of the North Sea by Oil and Other Harmful Substances (1983)

* Convention on Long-Range Transboundary Air Pollution (1979) and Protocols Relating to Financing of a European Monitoring Programme, Reduction of Sulphur Emissions, Nitrogen Oxide Emissions and Emissions of Volatile Organic Compounds.

* Convention on the Control of Transboundary Movements of Hazardous Wastes and their Disposal (1989).

* Convention on the Protection of the Black Sea Against Pollution (1992); and Protocols. Information for this backgrounder was found on the following websites:

* Destruction of Chemical Weapons:

* Bonn International Center for Conversion