Responding to the
Use of Chemical Weapons

The Chemical Weapons Convention codified an international norm against chemical weapons, to which all States Parties must adhere. Protecting this norm requires constant vigilance. While the work of the OPCW is largely focused on preventing the use of chemical weapons – through its verification activities, destruction of existing stockpiles, and capacity building in Member States –, it must also be ready to respond if and when chemical weapons are used. There are different ways in which the OPCW can respond to the use or alleged use of chemical weapons, ranging from carrying out a formal investigation to providing emergency assistance.

If a Member State considers that chemical weapons have been used against it, or it is threatened by actions prohibited by the Convention, it can request assistance from the OPCW.

Article X of the Convention sets out the procedure for requesting and receiving assistance against the use of chemical weapons. If there is proof that there are victims due to the use of chemical weapons and immediate action is indispensable, the Director-General is authorised to take emergency measures of assistance.

Investigations of Alleged Use

The Chemical Weapons Convention provides for investigations to be carried out by the Secretariat in connection with allegations of the use of chemical weapons under certain conditions. These investigations are technical in nature and are designed to establish whether or not chemical weapons have been used and identify the need for assistance to States Parties. If, in the course of the investigation, information is collected that may serve to identify the origin of any chemical weapons used, such information is to be included in the investigation report.

There are two ways in which an investigation of alleged use (IAU) of chemical weapons can be triggered. Both involve requests from States Parties. Articles IX and X of the Convention describe the applicable procedures. The first is by submission of a request by a State Party for a challenge inspection under Article IX where the alleged use occurred in another State Party. The second is by submission of a request for assistance in accordance with Article X in a situation in which chemical weapons are alleged to have been used against the requesting State Party, or riot control agents are alleged to have been used against it as a method of warfare. In the case of a request for assistance under Article X, an IAU is conducted with two purposes: 1) to establish facts related to the alleged use of chemical weapons, and 2) to provide a basis upon which the Executive Council can adopt a decision with regard to whether or not to instruct the Secretariat to take further action to assist the requesting State Party.

Once an IAU has been triggered under Article X of the Convention, the Director-General will dispatch an inspection team at the earliest opportunity. Upon entering the State Party in question, the inspection team is to have the right to access any areas that could have been affected by the alleged use of chemical weapons and other areas, such as hospitals and refugee camps. Members of the team may collect chemical, environmental and biomedical samples for analysis on-site or off-site at OPCW-designated laboratories. Inspection team members may also interview victims, eyewitnesses and medical personnel and participate in autopsies of persons who may have been affected by the alleged use of chemical weapons. Within 24 hours of arriving in the State Party having requested assistance under Article X of the Convention, the inspection team is to send a situation report to the Director-General. A preliminary report is to be submitted within 72 hours of the inspection team’s return to the OPCW’s headquarters in The Hague, while a final report is to be submitted within 30 days of the inspection team’s return. The Director-General is to transmit these reports to the Executive Council and to all States Parties. The Executive Council is to consider the reports and adopt decisions, as appropriate.

The OPCW may also conduct investigations under Article X in cases of alleged use of chemical weapons by or in States not Party to the Convention. In this line, pursuant to the Convention, the OPCW is to cooperate closely with the Secretary-General of the United Nations in connection with alleged uses of chemical weapons in States not Party to the Convention or in a territory not controlled by States Parties. If so requested, the Organisation is to put its resources at the disposal of the United Nations. Such a situation occurred in 2013 when the OPCW participated in the United Nations Mission to Investigate Allegations of the Use of Chemical Weapons in the Syrian Arab Republic, which was not then a State Party to the Convention. Investigators interviewed survivors and other witnesses, identified munitions used, collected biomedical and environmental samples and sent the samples to OPCW-designated laboratories for analysis. The investigations concluded that chemical weapons had been used.

Technical Assistance Visits

The Technical Secretariat provides advice and assistance, upon request, to States Parties that do not seek an investigation or a rapid response, but do wish to benefit from the Secretariat’s technical expertise. For example, such expertise may be needed for identifying chemical agents used in an attack.  The Secretariat is mandated by the Convention to provide such technical assistance, which may include visits to the State Party concerned.

Fact-Finding Mission

In response to persistent allegations of chemical weapons use in Syria, the OPCW Fact Finding Mission (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.

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. The FFM interviews witnesses and obtains samples and physical evidence for analysis. 

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

The FFM’s findings established the facts surrounding allegations of the use of toxic chemicals as weapons in Syria and confirmed that chemical weapons had been used. The FFM’s findings were the basis for the work of the OPCW-UN Joint Investigative Mechanism (JIM), an independent body established by the UN Security Council (Resolution 2235, 7 August 2015). The JIM’s purpose was to identify the perpetrators of the chemical weapon attacks confirmed by the Fact Finding Mission. The JIM’s mandate expired in November 2017.