Use of chemical weapons in the Syrian civil war

There have been numerous reports of chemical weapons attacks in the Syrian Civil War,^[1] beginning in 2012, and corroborated by national governments, the United Nations (UN),^[2] the Organisation for the Prohibition of Chemical Weapons (OPCW), Human Rights Watch (HRW), and media organizations. The attacks occurred in different areas of Syria, including Khan al-Assal, Jobar, Saraqib, Ashrafiyat Sahnaya, Kafr Zita, Talmenes, Sarmin and Douma. The deadliest attacks were the August 2013 sarin attack in Ghouta (killing between 281 and 1,729 people and injuring 3,600 patients), the April 2017 sarin attack in Khan Shaykhun (killing at least 89 people) and April 2018 Douma chemical attacks (killing 43 people and injuring 500 civilians). The most common agent used is chlorine (with one study finding it was used in 91.5% of attacks^[3]), with sarin and sulphur mustard also reported.^[4] Almost half of the attacks between 2014 and 2018 were delivered via aircraft and less than a quarter were delivered from the ground, with the remaining attacks having an undetermined method of delivery.^[4] Since the start of uprisings across Syria in 2011, Syrian Arab Armed Forces and pro-Assad paramilitary forces have been implicated in more than 300 chemical attacks in Syria.^[5]

Investigations have found that both the Syrian government of Bashar al-Assad and ISIL militants have used chemical weapons, with the majority of attacks being carried out by the Syrian government. In 2014, the OPCW Fact-Finding Mission in Syria concluded the use of chlorine was systematic and widespread.^[6] The following year, the OPCW-UN Joint Investigative Mechanism (OPCW-UN JIM) was established to identify the perpetrators of chemical attacks in Syria.^[6] The OPCW-UN JIM blamed the Syrian government of Bashar al-Assad for the sarin attack in Khan Shaykhun, as well as three chlorine attacks.^[6] They also concluded ISIL militants used sulphur mustard.^[6] According to the Independent International Commission of Inquiry on the Syrian Arab Republic, the Syrian government carried out 33 chemical attacks between 2013 and September 2018.^[7] A further six attacks were documented by the Commission, but the perpetrators were not sufficiently identified.^[7] According to HRW, 85 confirmed chemical attacks occurred between 21 August 2013 and 25 February 2018, and the Syrian government was responsible for the majority of the attacks.^[8][9] HRW said the actual number of attacks was likely higher than 85.^[8] According to a Global Public Policy Institute study, at least 336 attacks have occurred.^[3] The report said 98% of these attacks were carried out by Assad's forces and 2% by ISIL.^[3]

Attacks in 2013 prompted the international community to pressure the Syrian Armed Forces to agree to the supervised destruction of their chemical weapons. Despite the disarmament process, which completed on 23 June 2014, dozens of incidents with suspected use of chemical weapons followed throughout Syria, mainly blamed on Syrian Ba'athist forces, as well as ISIL, Syrian opposition forces, and Turkish Armed Forces.^[10] In April 2018, following at least 18 visits to Syria for inspections, the technical secretariat of the OPCW was unable to "verify that Syria had submitted a declaration that could be considered accurate and complete."^[6]

The Khan Shaykhun chemical attack on 4 April 2017 drew international condemnation, and resulted in U.S. military action against the Syrian government-controlled airbase at Shayrat. The Douma chemical attack on 7 April 2018 also drew a military response from the United States, United Kingdom and France. In April 2021, OPCW suspended Syria from its membership; criticising the Assad regime for not revealing its chemical weapon stockpiles and contravening the Chemical Weapons Convention.^[11][12][13]