Chemical Weapons ConventionCWCformally Convention on the Prohibition of the Development, Production, Stockpiling and Use of Chemical Weapons and on Their Destructioninternational treaty that bans the use of chemical weapons in war and also prohibits all development, production, acquisition, stockpiling, or transfer of such weapons. The CWC was adopted by the United Nations Conference on Disarmament on Sept. September 3, 1992, and the treaty was opened to signature by all states on Jan. January 13, 1993. The CWC entered into force on April 29, 1997. As of 20072010, the only countries that had neither signed nor acceded to the CWC were Angola, Egypt, Iraq, Lebanon, North Korea, Somalia, and Syria.
Negotiating a treaty

For almost a century before the CWC, a number of attempts had been made to limit or ban the use of chemical weapons in war. At the initiative of Nicholas II, emperor of Russia, delegates from around the world met at the 1899 and 1907 International Peace Conferences at The Hague. At the 1899 conference, the delegates agreed to prohibit the use of asphyxiating gases. Signatory states at both conferences agreed to prohibit the use of poison.

However, once chemical warfare was introduced on the battlefield by the German army in 1915, chemical weapons were produced and employed by all the powers participating in World War I, and more than a million chemical casualties and an estimated 91,000 fatalities resulted. Following the war, Germany was forbidden to manufacture or import poison gas munitions under the terms of the Treaty of Versailles (1919).


The 1925 Geneva Protocol banned the use of chemical and biological weapons but did not prohibit the development, production, stockpiling, or transfer of such weapons. Moreover, 25 of the signatory states reserved the right to retaliate in kind if another state used chemical weapons first. In reality, most of the powers that had signed the protocol had robust chemical warfare capabilities at the ready for use entering World War II, and all but Japan were deterred from use by the possession of such weapons by their adversaries.

After World War II, general multinational disarmament negotiations took place at the United Nations, including further discussions of limits to be put on chemical and biological weapons. Proposals were discussed at the Eighteen-Nation Disarmament Conference from 1962 to 1968 and then later in the UN Conference on Disarmament. Biological and chemical arms control were addressed separately. First to be addressed was biological disarmament, and this led to the negotiation, signature, and ratification of the Biological Weapons Convention in 1972.

After 1972 UN negotiators turned to chemical disarmament. In 1984 the United States tabled for consideration the first comprehensive detailed draft treaty by a major power. Real consensus had been blocked for a number of years by Cold War politics, and it was not until after Mikhail Gorbachev became general secretary of the Communist Party in 1985 that the Soviet Union began to also embrace comprehensive chemical arms control. By 1987 the two superpowers had begun to share a common perspective. While simultaneously working on a multilateral treaty, the United States and the Soviet Union, in a 1990 summit, also negotiated bilateral reductions of their chemical weapons. Each side agreed to reduce its stockpile to 5,000 tons of chemical agents.

With support finally coming from the United States and Russia (following the breakup of the Soviet Union), the UN Conference on Disarmament adopted the CWC treaty on Sept. September 3, 1992, and the treaty was opened to signature by all states on Jan. January 13, 1993. The CWC entered into force on April 29, 1997, 180 days after the deposit of the 65th instrument of ratification.

Aims and terms of the treaty

The aim of the CWC is total chemical weapons disarmament. Signatory states that possess chemical weapons at the time they sign and ratify the treaty must destroy those arms and their production facilities. States members are also required to destroy any chemical weapons they may have abandoned on the territory of other countries.

In Article II of the CWC, chemical weapons are defined as all toxic chemicals intended for wartime use, which includes not only the finished weapons but also their chemical precursors, munitions, delivery devices, and any other equipment specifically designed for wartime use.

Certain kinds of toxic chemicals are, however, permitted by the CWC. These include those designed for peaceful uses, such as in experiments to test chemical protection equipment. There are also certain gray areas in the treaty that are open to interpretation. For example, riot-control agents such as tear gas are prohibited as a method of warfare, but they are permitted if designed strictly for law-enforcement purposes.

Chemicals to be controlled by the CWC are divided among three lists, or “schedules.” Schedule 1 lists those chemicals considered to pose a high risk to the goals of the CWC, including precursor chemicals used to produce nerve agents or mustard agents. Schedule 2 lists those chemicals that generally are not produced in large commercial quantities for nonmilitary purposes and pose a significant risk to the purpose of the CWC. Finally, those listed in Schedule 3 are dual-use chemicals that are thought to pose a risk to the aims of the CWC but also have many legitimate commercial purposes and are produced worldwide in large amounts.

Ensuring compliance

The CWC is administered by the Organisation for the Prohibition of Chemical Weapons (OPCW), headquartered at The Hague. Day-to-day affairs are conducted by the OPCW’s Executive Council, which reports to the CWC’s Conference of States Parties. This latter body in turn has responsibility for taking “the necessary measures to ensure compliance” and for administering penalties against signatory states that violate the terms of the CWC. The OPCW Technical Secretariat is responsible for carrying out various verification procedures to ensure that members comply with the agreement.

CWC verification is accomplished by a variety of means, including reporting requirements by the member states, OPCW inspections to determine a baseline for comparison with later inspections, regular on-site inspections, and challenge inspections. Any single party to the pact can request a challenge inspection of any other signatory party. Inspectors are to be given unimpeded access to all parts of actual or suspected chemical weapons storage sites or to chemical production or destruction facilities. OPCW inspectors are permitted by the treaty to use continuous on-site monitoring devices and may use seals to ensure that a facility is not being used. The OPCW Technical Secretariat must give a member state prior notice of an impending regular inspection to a storage site. Sites that previously produced or are presently known or suspected to be storage areas for Schedule 1 chemical weapons or agents receive the most scrutiny.

Within 12 hours of receiving a challenge inspection request, the Executive Council of the OPCW may block the inspection if three-fourths or more of the 41 members on the Council are convinced that the request is frivolous or abusive. The director-general of the OPCW is required to formally notify the party to be inspected no less than 12 hours prior to the planned arrival of the inspection team. A series of rules then apply as to how inspectors can gain access to facilities in order to check compliance with CWC restrictions.

Each party to the accord is required to pass national implementing legislation to make it illegal for organizations or individuals in their jurisdiction to conduct activities prohibited by the CWC, such as the use, development, production, acquisition, stockpiling, or transfer of chemical arms.