Douma chemical attack

On 7 April 2018, a chemical warfare attack was launched in the city of Douma, Syria by the military of the Ba'athist regime led by Bashar al-Assad. Medics and witnesses reported that it caused the deaths of between 40 and 50 people and injuries to possibly well over 100. The attack was attributed to the Syrian Army by rebel forces in Douma, and by the United States, British, and French governments. A two-year long investigation by the Organisation for the Prohibition of Chemical Weapons (OPCW) Investigation and Identification Team (IIT) concluded in January 2023 that the Syrian Air Force perpetrated the attack, dropping two cylinders, one of which hit the rooftop floor of a three-storey residential building and released chlorine gas. On 14 April 2018, the United States, France and the United Kingdom carried out a series of military strikes against two alleged chemical weapons facilities of the Syrian government.

According to Organisation for the Prohibition of Chemical Weapons (OPCW) and United Nations investigations, both the Syrian Arab Republic's forces and Islamic State militants have used chemical weapons during the conflict. Human Rights Watch has documented 85 chemical weapons attacks in Syria since 2013, and its sources indicate the Syrian government is responsible for the majority. People reported incidents of chemical weapons use specifically in Douma in January 2018; Russia vetoed a potential United Nations mission to investigate. The Arms Control Association reported two smaller chlorine gas attacks in Douma on 7 March and 11 March.

Douma had been under rebel control since 18 October 2012, and, with the rest of the Eastern Ghouta region, under siege since April 2013. The Rif Dimashq offensive (February–April 2018), code-named Operation Damascus Steel, a military offensive launched by the Syrian Arab Army (SAA) and its allies on 18 February 2018 to capture the rebel-held territory. The Jaysh al-Islam rebel coalition controlled Douma. By mid-March, rebel territory in Eastern Ghouta had reduced to three pockets, one in the south around Hamouria held by Faylaq al-Rahman; a second in the west around Harasta held by Ahrar al-Sham; as well as Douma in the north held by Jaysh al-Islam. In the second half of March, the other two pockets were secured via evacuation deals between the rebels, Syria, and Russia. On 31 March, the last of the evacuations was conducted and the Syrian army declared victory in Eastern Ghouta, while the rebels that were still holding out in Douma were given an ultimatum to surrender by the end of the day.

A chemical attack in Douma occurred on 7 April 2018. The Union of Medical Care and Relief Organizations, a humanitarian organization that supervises medical services in the region, attributed seventy deaths to the attack. On-site medics reported smelling a chlorine-like odour, but that symptoms and death toll pointed to something more noxious such as sarin nerve agent caused the deaths. A video from the scene showed dead men, women, and children with foam at their mouths. The Syrian American Medical Society (SAMS) reported over 500 injured people at Douma "were brought to local medical centers with symptoms indicative of exposure to a chemical agent." SAMS also said a chlorine bomb struck a Douma hospital, killing six people, and that another attack with "mixed agents" affected a building nearby. According to the Syrian opposition groups, witnesses also reported a strong smell of chlorine and said effects appeared stronger than in previous similar attacks. Syrian opposition activists also posted videos of yellow compressed gas cylinders that they said were used during the attack. Based on the symptoms and the speed with which the victims were affected, medical workers and experts suggested either a combination of chlorine with another gas or a nerve agent was used. Several medical, monitoring, and activist groups—including the White Helmets—reported that two Syrian Air Force Mi-8 helicopters dropped barrel bombs on the city of Douma. The bombs caused severe convulsions in some residents and suffocated others.

On 6 July 2018, an interim report was issued by the 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 United Nations 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."

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." The OPCW said it found no evidence to support the Assad government's claim that a local facility was being used by rebel fighters to produce chemical weapons.

The day after the chemical attack, all rebels controlling Douma agreed to a deal with the government to surrender the area.

In the early hours of 9 April 2018, an air strike was conducted against Tiyas Military Airbase. Two Israeli F-15I jets reportedly attacked the airfield from Lebanese airspace, firing eight missiles, of which five were intercepted, according to claims by Russia. According to the Syrian Observatory for Human Rights monitor, at least 14 people were killed and more were wounded.