OPCW Fact-Finding Mission concludes investigation on reported allegations in Kharbit Massasneh, Syria

4 July 2023

THE HAGUE, Netherlands—4 July 2023—The Fact-Finding Mission (FFM) of the Organisation for the Prohibition of Chemical Weapons (OPCW) concluded that there are no reasonable grounds to determine that chemicals were used as a weapon in the reported incidents which occurred in Kharbit Massasneh on 7 July 2017 and 4 August 2017.

On 26 October 2017, the Syrian Arab Republic reported to the OPCW Technical Secretariat a “mortar attack with poisonous gas” on positions of the Syrian Arab Army in Kharbit Massasneh resulting in several casualties among soldiers. The Syrian Arab Republic requested the Technical Secretariat to investigate both incidents.

The FFM obtained information regarding the incidents from different sources, including interviews with witnesses, videos, and photographs of medical records. In addition, the FFM exchanged correspondence and held meetings with the Syrian Arab Republic to clarify inconsistencies observed in the course of its investigation.

Based on the examination of all data obtained and collected and on the analysis of all evidence taken as a whole, the FFM concludes that there are no reasonable grounds to determine that chemicals were used as a weapon in any of the two reported incidents.

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

Read the full report.


With repeated allegations of the use of toxic chemicals for hostile purposes at a number of locations in the Syrian Arab Republic, on 29 April 2014, the OPCW Director-General announced the formation of the OPCW Fact Finding Mission (FFM). The establishment of the FFM was based on the general authority of the OPCW Director-General to seek to uphold at all times the object and purpose of the Chemical Weapons Convention. This authority is reinforced by the relevant decisions of the OPCW Executive Council and the United Nations Security Council resolution (UNSCR) 2118 (2013); and its acceptance by the Syrian Arab Republic. Its creation is also based on terms of reference agreed between the Secretariat and the Syrian National Authority.

The FFM is responsible for determining whether toxic chemicals have been used as weapons in the Syrian Arab Republic. The mandate does not include identifying who is responsible for any alleged attacks. On the basis of the FFM’s findings, the OPCW Investigation and Identification Team (IIT) (as the OPCW-UN Joint Investigative Mechanism (JIM) did previously), collects and analyses evidence that may help to identify the perpetrators of chemical weapons attacks in Syria. 

To date, the FFM has issued 20 reports covering 73 instances of alleged chemical weapons use. The FFM concluded that chemical weapons were used or likely used in 20 instances: in 14 cases the chemical used was chlorine, in three cases the chemical used was Sarin, and in three cases the chemical used was mustard agent. These reports were submitted to the States Parties of the Chemical Weapons Convention and the UN Security Council. All FFM reports are published on the OPCW website

More Information