Syria 's chemical weapons program began in the 1970 's with weapons and training from Egypt and the Soviet Union , with production of chemical weapons in Syria beginning in the mid-1980 's . For some time , Syria was believed to have the world 's third-largest stockpile of chemical weapons , after the United States and Russia . Prior to September 2013 Syria had not publicly admitted to possessing chemical weapons , although Western intelligence services believed it to hold one of the world 's largest stockpiles . In September 2013 , French intelligence put the Syrian stockpile at 1,000 tonnes , including Yperite , VX and " several hundred tonnes of sarin " . At the time , Syria was one of a handful of states which had not ratified the Chemical Weapons Convention . In September 2013 , Syria joined the CWC ( formally acceding on 14 October ) , and agreed to the destruction of its weapons , to be supervised by the Organisation for the Prohibition of Chemical Weapons ( OPCW ) , as required by the Convention . A joint OPCW-United Nations mission was established to oversee the destruction process . Syria joined OPCW after international condemnation of the August 2013 Ghouta chemical attack , for which Western states held the Syrian government responsible ( whilst Syria and Russia held the Syrian rebels of the Syrian civil war responsible ) and agreed to the prompt destruction of its chemical weapons , resulting in U.S. Secretary of State John Kerry declaring on 20 July 2014 : " we struck a deal where we got 100 percent of the chemical weapons out . " The destruction of Syria 's chemical weapons that the Assad government had declared was completed by August 2014 , yet further disclosures , incomplete documentation , and allegations of withholding part of Syria 's chemical weapons stockpile since mean that serious concerns regarding chemical weapons and related sites in Syria remain . On 5 April 2017 , the government of Syria allegedly unleashed a chemical attack that killed 70 civilians . A suspected chemical attack on Douma on 9 April 2018 that killed at least 49 civilians has been blamed on the Syrian Government
Ghouta chemical attack
Ghouta chemical attack
Syria chemical weapons program