On 21 August 2013 two opposition-controlled areas in the suburbs around Damascus , Syria were struck by rockets containing the chemical agent sarin . Estimates of those killed by the attack ranged from 281 to 1,729 . The attack was the deadliest use of chemical weapons since the Iran – Iraq War . Following an inspection by a UN investigation team confirmed " clear and convincing evidence " of the use of sarin delivered by surface-to-surface rockets , a 2014 report by the UN Human Rights Council found that " significant quantities of sarin were used in a well-planned indiscriminate attack targeting civilian-inhabited areas , ... The evidence available concerning the nature , quality and quantity of the agents used on 21 August indicated that the perpetrators likely had access to the chemical weapons stockpile of the Syrian military , as well as the expertise and equipment necessary to manipulate safely large amount of chemical agents . " Based on the trajectories calculated by the UN mission , Human Rights Watch states that the missiles were launched from a large military base on Mount Qasioun which is home to the Republican Guard 104th Brigade
struck
Ghouta chemical attack
Human rights violations during the Syrian Civil War