OPCW issues Fact-Finding Mission report on chemical weapons use allegation in Marea, Syria, in September 2015

Report concludes chemical blister agent was used as a weapon

26 January 2022

THE HAGUE, Netherlands—26 January 2022—The Fact-Finding Mission (FFM) of the Organisation for the Prohibition of Chemical Weapons (OPCW), issued on 24 January its report on the FFM’s investigation regarding incidents of alleged use of toxic chemicals as a weapon in Marea, Aleppo Governorate, Syrian Arab Republic, on 1 and 3 September 2015.

The FFM obtained information regarding the incidents that took place in Marea on 1 and 3 September 2015 through several activities and from different sources. The FFM was able to conduct interviews with witnesses and obtained environmental samples in addition to digital evidence.

On 1 and 3 September 2015, the town of Marea was subject to shelling with both conventional munitions as well as projectiles filled with chemicals that fell in various locations and neighbourhoods in Marea. In some of the targeted locations, a black substance was observed, and in others, a yellow powder was observed. Individuals exposed to the substances developed blisters a few hours after exposure. Affected individuals displayed similar signs and symptoms in both incidents.

The report reached the conclusion that there are reasonable grounds to believe that on 1 September 2015 in Marea, a vesicant chemical substance from Schedule 1.A.04 of the Chemical Weapons Convention was used as a weapon.

Information obtained and analysed by the FFM on the incident that occurred on 3 September 2015 in Marea was not sufficient to allow the FFM to establish with reasonable grounds whether chemicals were or were not used as a weapon.

The FFM report was shared with States Parties to the Chemical Weapons Convention. The report was also transmitted to the United Nations Security Council through the UN Secretary-General.


In response to persistent allegations of chemical weapon attacks in Syria, the OPCW Fact-Finding Mission (FFM) was set up in 2014 with an on-going mandate “to establish facts surrounding allegations of the use of toxic chemicals, reportedly chlorine, for hostile purposes in the Syrian Arab Republic”.

The FFM’s mandate is to determine whether chemical weapons or toxic chemicals as weapons have been used in Syria. It does not include identifying who is responsible for alleged attacks. 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 bio-medical samples and physical evidence for analysis.

Following the Decision on “Addressing the threat from chemical weapons use”, adopted by the Conference of the States Parties at its Special Session in June 2018, the Technical Secretariat has put in place arrangements to identify the perpetrators of the use of chemical weapons in the Syrian Arab Republic.

The FFM has previously determined that the use of chlorine, sulfur mustard, and sarin as chemical weapons took place in other incidents in the Syrian Arab Republic.

The OPCW 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.

As the implementing body for the Chemical Weapons Convention, the OPCW, with its 193 Member States, oversees the global endeavour to permanently eliminate chemical weapons. Since the Convention’s entry into force in 1997, it is the most successful disarmament treaty eliminating an entire class of weapons of mass destruction.

Over 99% of all declared chemical weapon stockpiles have been destroyed under OPCW verification. For its extensive efforts in eliminating chemical weapons, the OPCW received the 2013 Nobel Peace Prize.

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