“Right after I graduated, I interned with the Arms Control Association. It was terrific.”

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ABC News
January 1, 2005
The Chemical Weapons Convention (CWC) at a Glance
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Last Reviewed: 
April 2023

Contact: Daryl G. Kimball, Executive Director, 202-463-8270 x 107

The Chemical Weapons Convention (CWC) is a multilateral treaty that bans chemical weapons and requires their destruction within a specified period of time. The treaty is of unlimited duration and is far more comprehensive than the 1925 Geneva Protocol, which outlaws the use but not the possession of chemical weapons.

CWC negotiations started in 1980 in the UN Conference on Disarmament.  The convention opened for signature on January 13, 1993, and entered into force on April 29, 1997.

The CWC is implemented by the Organization for the Prohibition of Chemical Weapons (OPCW), which is headquartered in The Hague with about 500 employees. The OPCW receives states-parties’ declarations detailing chemical weapons-related activities or materials and relevant industrial activities. After receiving declarations, the OPCW inspects and monitors states-parties’ facilities and activities that are relevant to the convention, to ensure compliance.

The CWC is open to all nations and currently has 193 states-parties. Israel has signed but has yet to ratify the convention. Three states have neither signed nor ratified the convention (Egypt, North Korea and South Sudan).


The Chemical Weapons Convention prohibits:

  • Developing, producing, acquiring, stockpiling, or retaining chemical weapons.
  • The direct or indirect transfer of chemical weapons.
  • Chemical weapons use or military preparation for use.
  • Assisting, encouraging, or inducing other states to engage in CWC-prohibited activity.
  • The use of riot control agents “as a method of warfare.”

Declaration Requirements

The CWC requires states-parties to declare in writing to the OPCW their chemical weapons stockpiles, chemical weapons production facilities (CWPFs), relevant chemical industry facilities, and other weapons-related information. This must be done within 30 days of the convention's entry into force for each member state.

Chemical Weapons Stockpiles—States-parties must declare all chemical weapons stockpiles, which are broken down into three categories:

  • Category 1: chemical weapons based on Schedule 1 chemicals, including VX and sarin. (See below for an explanation of “scheduled” chemicals.)
  • Category 2: chemical weapons based on non-Schedule 1 chemicals, such as phosgene.
  • Category 3: chemical weapons including unfilled munitions, devices and equipment designed specifically to employ chemical weapons.

Other weapons-related declarations states-parties must make include:

  • Chemical weapons production facilities on their territories since January 1, 1946.
  • Facilities (such as laboratories and test sites) designed, constructed, or used primarily for chemical weapons development since January 1, 1946.
  • “Old” chemical weapons on their territories (chemical weapons manufactured before 1925 or those produced between 1925 and 1946 that have deteriorated to such an extent that they are no longer useable).
  • “Abandoned” chemical weapons (abandoned by another state without consent on or after January 1, 1925).
  • Plans for destroying weapons and facilities.
  • All transfers or receipts of chemical weapons or chemical weapons-production equipment since January 1, 1946.
  • All riot control agents in their possession.

Chemical Industry—The CWC requires states-parties to declare chemical industry facilities that produce or use chemicals of concern to the convention. These chemicals are grouped into “schedules,” based on the risk they pose to the convention. A facility producing a Schedule 1 chemical is considered a Schedule 1 facility.

  • Schedule 1 chemicals and precursors pose a “high risk” to the convention and are rarely used for peaceful purposes. States-parties may not retain these chemicals except in small quantities for research, medical, pharmaceutical, or defensive use. Many Schedule 1 chemicals have been stockpiled as chemical weapons.
  • Schedule 2 chemicals are toxic chemicals that pose a “significant risk” to the convention and are precursors to the production of Schedule 1 or Schedule 2 chemicals. These chemicals are not produced in large quantities for commercial or other peaceful purposes.
  • Schedule 3 chemicals are usually produced in large quantities for purposes not prohibited by the CWC but still pose a risk to the convention. Some of these chemicals have been stockpiled as chemical weapons.

The CWC also requires the declaration of facilities that produce certain nonscheduled chemicals.


Destruction Requirements

The convention requires states-parties to destroy:

  • All chemical weapons under their jurisdiction or control.
  • All chemical weapons production facilities under their jurisdiction or control.
  • Chemical weapons abandoned on other states’ territories.
  • Old chemical weapons.

Category 1 chemical weapons destruction must start within two years after the CWC enters into force for a state-party. States-parties must destroy 1 percent within three years of the CWC's entry into force, 20 percent within five years, 45 percent within seven years, and 100 percent within 10 years. States parties that signed the treaty when it entered into force in 1997 were supposed to complete destruction of category 1 chemicals by April 29, 2007.

States-parties that signed the treaty when it entered into force were supposed to destroy their entire stockpiles by April 29, 2012. However, the OPCW decided to extend these deadlines due to “exceptional circumstances,” and in December 2006, the OPCW Executive Council granted nearly all possessors extensions of differing lengths. The only exception was Albania, which was the sole state-party nearing the complete destruction of its stockpile at that time.

Category 2 and 3 chemical weapons destruction must start within one year after the CWC enters into force for a state-party.

Destruction of CWPFs capable of producing Schedule 1 chemicals must start within one year after the CWC enters into force for a state-party. States-parties that signed the treaty when it originally entered into force had to complete of CWPFs producing schedule 1 chemicals by April 29, 2007.

Destruction of other CWPFs must start within one year after the CWC enters into force for a state-party. States-parties that signed the treaty when it originally entered into force had to complete destruction by April 29, 2002.

States-parties may request to convert CWPFs to facilities that they can use for nonprohibited purposes. Once their requests are approved, states-parties that signed the treaty when it originally entered into force were supposed to complete conversion by April 29, 2003.

On-Site Activity

The convention establishes three types of on-site activities that aim to generate confidence in states-parties’ CWC compliance. These include:

  • “Routine inspections” of chemical weapons-related facilities and chemical industry facilities to verify the content of declarations and to confirm that activities are consistent with CWC obligations.
  • “Challenge inspections” which can be conducted at any facility or location in states-parties to clarify questions of possible noncompliance. (To prevent abuse of this measure, the OPCW’s executive body can vote by a three-quarters majority to stop a challenge inspection from going forward.)
  • Investigations of alleged use of chemical weapons.


The convention encourages trade among states-parties, calling upon them not to maintain restrictions on one another that would hamper the trade of chemical-related items to be used for peaceful purposes. The convention does restrict trade with non-states-parties, outlawing the transfer of Schedule 1 and 2 chemicals.  To ensure that Schedule 3 transfers to non-states-parties are not used for purposes prohibited by the convention, the CWC requires exporting states-parties to obtain an end-use certificate from importing states.

Penalties for Noncompliance

If states-parties are found to have engaged in prohibited actions that could result in “serious damage” to the convention, the OPCW could recommend collective punitive measures to other states-parties. In cases of “particular gravity,” the OPCW could bring the issue before the UN Security Council and General Assembly.

States-parties must take measures to address questions raised about their compliance with the CWC. If they do not, the OPCW may, inter alia, restrict or suspend their CWC-related rights and privileges (such as voting and trade rights).

Sources: Arms Control Association, OPCW (http://www.opcw.org/news-publications/publications/facts-and-figures/)

Possessor States' Category I Destruction Implementation


Declared Category 1 Stockpile

Declared Agents

Remaining Stockpile



16 metric tons



Completed destruction on July 11, 2007.


1,044 metric tons

Sulfur Mustard


Completed destruction on March 16, 2009


Unknown Quantity



The OPCW announced the destruction of Iraq's chemical weapons remnants on March 13, 2018.


24.7 metric tons1

Sulfur Mustard


Completed destruction of Category 1 chemicals on May 4, 2013


40,000 metric tons

Lewisite, Mustard, Phosgene, Sarin, Soman, VX


Completed destruction on September 27, 2017.

South Korea

605 metric tons



Completed destruction on July 10, 2008.


1,308 metric tons

Sulfur Mustard

Declared stockpile has been eliminated but undeclared chemicals still exist

No projected timeline for destruction of undecared chemicals.

United States

27,771 metric tons

Binary nerve agents, Lewisite, Mustard, Sarin, Soman, VX


U.S. completed its destruction process in July 2023.

1. Libya's official 2004 declaration was 24.7 metric tons. Libya declared additional CW stocks in November 2011 and February 2012, bringing the total to 26.3 metric tons.