On 14 April 2018, the United States, France and the United Kingdom carried out a series of military strikes against multiple government sites in Syria.

On 6 July 2018, an interim report was issued by the Organisation for the Prohibition of Chemical Weapons (OPCW). Various chlorinated organic chemicals (dichloroacetic acid, trichloroacetic acid, chlorophenol, dichlorophenol, bornyl chloride, chloral hydrate etc.) were found in samples, along with residues of explosive, but the designated laboratory 03 stated that no CWC-scheduled chemicals or nerve agent related chemicals were detected. In September 2018 the UN Commission of Enquiry on Syria reported: "Throughout 7 April, numerous aerial attacks were carried out in Douma, striking various residential areas. A vast body of evidence collected by the Commission suggests that, at approximately 7.30 p.m., a gas cylinder containing a chlorine payload delivered by helicopter struck a multi-storey residential apartment building located approximately 100 metres south-west of Shohada square. The Commission received information on the death of at least 49 individuals, and the wounding of up to 650 others."[3]

While it was initially unclear which chemicals had been used, in 2019 the OPCW FFM (Fact-Finding Mission) report concluded: "Regarding the alleged use of toxic chemicals as a weapon on 7 April 2018 in Douma, the Syrian Arab Republic, the evaluation and analysis of all the information gathered by the FFM—witnesses' testimonies, environmental and biomedical samples analysis results, toxicological and ballistic analyses from experts, additional digital information from witnesses—provide reasonable grounds that the use of a toxic chemical as a weapon took place. This toxic chemical contained reactive chlorine. The toxic chemical was likely molecular chlorine."[1]: 9.12  The OPCW said it found no evidence to support the government's claim that a local facility was being used by rebel fighters to produce chemical weapons.[13] [54T5D3F3]