The Fact-Finding Mission of the Organisation for the Prohibition of Chemical Weapons (OPCW) concluded on Monday that there were no reasonable grounds to determine that toxic chemicals were used by the Islamic State of Iraq and the Levant (ISIL) in October 2017 at Al-Yarmouk in the Syrian Arab Republic. 

In its report, OPCW found that there was no indication that chemicals were used as a weapon by ISIL. However, the organization noted evidence gathering has become increasingly complex, with several potential witnesses having died during the conflict or are still missing. Likewise, individuals who initially agreed to provide testimony ultimately declined to provide their account of the events to the OPCW. 

This follows a finding in February 2024 that ISIL was responsible for the 2015 chemical attack in Marea, Syria. These reports come as the OPWC parses through the allegations of chemical weapon usage by all parties of the Syrian Civil War, which began in 2011. 

These conflicting reports add complexity to international actions against parties to the Syrian Civil War. The use of chemical weapons in Syria became a cause celebre, with the US launching missile strikes in 2017 and 2018, allegedly in retaliation to the Syrian government’s use of chemical weapons. In November 2023, Al Jazeera reported that France had issued arrest warrants against Assad and another government official for the alleged use of chemical weapons during the Civil War. The Syrian regime has consistently denied claims that it had used chemical weapons, citing a 2013-2014 joint OPCW-UN mission that purported to have removed or destroyed all chemical weapons held by the Syrian government and has blamed all chemical attacks on opposing groups.