The report bases its conclusions on testimony from witnesses and medical staff as well analysis of the armaments used, which HRW said were of a type used only by the Syrian military. The effect on the victims pointed to a nerve agent, “most likely sarin”.
It says it is impossible so far to give an exact death toll, but noted that the estimate in just one district was over 700 and that Médecins Sans Frontières had reported that at least 3,600 people were treated for symptoms consistent with exposure to neurotoxins.
Even though Damascus has not signed the 1993 chemical weapons convention, Bashar al-Assad’s regime is still in violation of international law, the report argues, as it signed the 1925 Geneva gas protocol prohibiting use of such weapons. It adds: “Customary international law bans the use of chemical weapons in all armed conflicts.”
The report’s author, Peter Bouckaert, does not explicitly call for a punitive response but argues the 21 August poison gas massacre in the rebel-held Ghouta suburbs “should refocus the international debate on deterring the use of such weapons and more broadly protecting Syria’s civilian population”.
Bouckaert found that two types of projectiles were used to spread the nerve agent in attacks on eastern and western Ghouta. The first was a 330mm rocket “that appears to have a warhead designed to be loaded with and deliver a large payload of liquid chemical agent”.
He said the other type, used in the western Ghouta attack, was a Soviet-produced 140mm rocket that can deliver three possible warheads, one of them specifically designed to carry 2.2kg of sarin.
“Human Rights Watch and arms experts monitoring the use of weapons in Syria have not documented Syrian opposition forces to be in the possession of the 140mm and 330mm rockets used in the attack or their associated launchers,” Bouckaert said.
He said the Syrian government had presented no credible evidence to support its claims that the chemical attack was carried out by rebels on their own supporters. The report states that such claims are “lacking in credibility and inconsistent with the evidence found at the scene”.
Bouckaert said: “This evidence strongly suggests that Syrian government troops launched rockets carrying chemical warheads into the Damascus suburbs that terrible morning.”
HRW was not able to gain access to the scene of the attack but instead carried out interviews with survivors and medical staff, and analysed pictures of rocket fragments taken by the group’s sources in Damascus.