Understanding the OPCW and the Chemical Weapons Convention

The Organisation for the Prohibition of Chemical Weapons (OPCW) is a treaty-based international organisation that operates according to a strict confidentiality regime, which governs the operations of the Organisation, protects the integrity of its investigations, ensures the security of its technical experts, and determines what information can be made public.

The OPCW is responsible for the implementation of the Chemical Weapons Convention (CWC), which comprehensively prohibits the use, development, production, stockpiling and transfer of chemical weapons.

The Chemical Weapons Convention prohibits the use of toxic chemicals to kill or harm, regardless of their source.

OPCW, the Chemical Weapons Convention, and the Syrian Arab Republic

Syria became a State Party to the Chemical Weapons Convention and a Member State of the OPCW in October 2013. As a result of a joint OPCW-UN mission, in cooperation with the Syrian government, all of the chemical weapons declared by Syria were removed and destroyed outside of Syrian territory.

Questions have been raised as to whether Syria’s declaration about its chemical weapons programme to the OPCW was complete and correct. In 2014, the OPCW Director-General established a team of experts from the Technical Secretariat to engage the relevant Syrian authorities to resolve the identified gaps and inconsistencies in the Syrian declaration. The team of experts known as the Declaration Assessment Team (DAT) undertook 18 visits to Syria, held several meetings with Syrian authorities, visited former chemical weapons sites, and took samples. The DAT has submitted several reports to States Parties of the Chemical Weapons Convention.

In July 2016, the Director-General informed the Executive Council, through his report to the Council’s 82nd session, that the Technical Secretariat was not able to resolve all identified gaps, inconsistencies and discrepancies in Syria’s declaration and therefore could not fully verify that Syria had submitted a declaration that could be considered accurate and complete in accordance with the Chemical Weapons Convention and Executive Council decision ECM-33/DEC.5. The Director-General submitted his report after high-level consultations with the Syrian Arab Republic.

Starting in 2013, the OPCW has adapted itself in unprecedented ways, such as the joint OPCW-UN Mission with the support of 30 nations to remove, transport and destroy Syria’s declared chemical weapons stockpile in the midst of an active conflict zone.

In accordance with CWC and the relevant decisions of the OPCW Executive Council as well as UN Security Council Resolution 2118 (2013), the Syrian Arab Republic and all groups and parties in Syria are obliged not to develop, produce, retain or use chemical weapons or toxic chemicals as weapons.

OPCW Response to the 4 April 2017 Incident

The OPCW is investigating the incident in southern Idlib under the on-going mandate of the Fact-Finding Mission (FFM), which is “to establish facts surrounding allegations of the use of toxic chemicals, reportedly chlorine, for hostile purposes in the Syrian Arab Republic”. The OPCW cannot and will not release information about an on-going investigation. This policy exists to preserve the integrity of the investigatory process and its results as well as to ensure the safety and security of OPCW experts and personnel involved. All parties are asked to respect the confidentiality parameters required for a rigorous and unimpeded investigation.

The OPCW Technical Secretariat has initiated contact with the Syrian authorities. It has also requested that all States Parties to the Chemical Weapons Convention, in a position to do so, share any information they may have regarding the allegations of chemical weapons use in the Khan Sheikhun area of Idlib province in the Syrian Arab Republic.

The findings of the FFM will be submitted in a report to the OPCW Executive Council and States Parties of the Chemical Weapons Convention.

In response to persistent allegations of chemical weapon attacks in Syria, the FFM was set up in 2014 “to establish facts surrounding allegations of the use of toxic chemicals, reportedly chlorine, for hostile purposes in the Syrian Arab Republic”. The FFM is required to study available information relating to allegations of use of chemical weapons in Syria, including information provided by the Syrian Arab Republic and others. The FFM employs investigative methods to determine if chemical weapons have been used. It interviews witnesses and obtains environmental and biomedical samples and physical evidence for analysis.

Since May 2014, the OPCW has deployed the FFM in numerous occasions to the Syrian Arab Republic and outside of Syria and has kept States Parties informed of its work.

In 2015, the OPCW Executive Council and the UN Security Council endorsed the continual operation of the FFM.

Since its establishment, the FFM has looked into several incidents of allegations of use of chemical weapons in Syria. In this context, the FFM has confirmed with “high degree of confidence” that Chlorine and Mustard were used as weapons in its investigations into past allegations of chemical weapons use. These reports were submitted to States Parties to the CWC and also transmitted to the UN Security Council.

The OPCW-UN Joint Investigative Mechanism

The OPCW-UN Joint Investigative Mechanism (JIM) was established by the UN Security Council (Resolution 2235, 7 August 2015) with the mandate to identify “to the greatest extent feasible” individuals, entities, groups, or governments who were perpetrators, organisers, sponsors or otherwise involved in the use of chemicals as weapons in Syria, where the OPCW FFM determines or has determined that a specific incident involved or likely involved the use of chemicals as weapons.

The JIM, as a subsidiary organ of the United Nations Security Council, carries out its further investigations and makes its findings as an independent body. It presents its reports to the Security Council, and informs the OPCW.

Inquiries about the JIM should be directed to:



OPCW-UN Joint Investigative Mechanism

304 East 45th Street,

FF Building, 17th Floor

New York, NY 10017

E-mail: jimquery@un.org

Other Resources

Selected Press Releases about the OPCW Fact-Finding Mission

Selected Press Releases about OPCW-UN Joint Mission

Posters and Fact Sheets