NEW YORK — A UN report released Monday confirmed that a deadly chemical arms attack caused a mass killing in Syria last month and for the first time provided extensive forensic details of the weapons used, which strongly implicated the Syrian government.
While the report’s authors did not assign blame for the attack on the outskirts of Damascus, the details it documented included the large size and particular shape of the munitions and the precise direction from which two of them had been fired. Taken together, that information appeared to undercut arguments by President Bashar Assad of Syria that rebel forces, who are not known to possess such weapons or the training or ability to use them, had been responsible.
The report, commissioned by Secretary General Ban Ki-moon, was the first independent on-the-ground scientific inquest into the attack, which left hundreds of civilians gassed to death, including children, early on Aug. 21.
The repercussions have elevated the 30-month-old Syrian conflict into a global political crisis that is testing the limits of impunity over the use of chemical weapons. It could also lead to the first concerted action on the war at the UN Security Council, which until now has been paralyzed over Syria policy.
“The report makes for chilling reading,” Ban told a news conference after he briefed the Security Council. “The findings are beyond doubt and beyond the pale. This is a war crime.”
Ban declined to ascribe blame, saying that responsibility was up to others, but he expressed hope that the attack would become a catalyst for a new diplomatic determination at the United Nations to resolve the Syrian conflict, which has left more than 100,000 people dead and millions displaced.
There was no immediate reaction to the report from the Syrian government. But just two days before the report was released, Syria officially agreed to join the international convention on banning chemical weapons, and the United States and Russia, which have repeatedly clashed over Syria, agreed on a plan to identify and purge those weapons from the country by the middle of next year. Syria has said it would abide by that plan.
The main point of the report was to establish whether chemical weapons had been used in the Aug. 21 attack in the Damascus suburb of Ghouta, an area long infiltrated by rebels. The UN inspectors concluded that “chemical weapons have been used in the ongoing conflict between the parties in the Syrian Arab Republic, also against civilians, including children, on a relatively large scale.”
The weapons inspectors, who visited Ghouta and left the country with large amounts of evidence on Aug. 31, said, “In particular, the environmental, chemical and medical samples we have collected provide clear and convincing evidence that surface-to-surface rockets containing the nerve agent sarin were used.”
But the report’s annexes, detailing what the authors found, were what caught the attention of nonproliferation experts.
In one particularly incriminating piece of information, the inspectors said the remnants of a warhead found in the attack’s aftermath showed its capacity of sarin to be about 56 liters — far larger than the suspected delivery systems used in alleged chemical weapons attacks before the Aug. 21 strike.
The investigators were unable to examine all of the munitions used but did find and measure several rockets or their components. Using standard field techniques for ordnance identification and crater analysis, they established that at least two types of rockets had been used, including an M14 artillery rocket bearing Cyrillic markings and a 330-millimeter rocket of unidentified provenance.
Nonproliferation experts said the report was damning in its implicit incrimination of Assad’s side in the conflict, not only in the weaponry fragments but data that indicated the attack’s origins. An analysis of the report posted online by the Arms Control Association, a Washington-based advocacy group, said “the additional details and the perceived objectivity of the inspectors buttress the assignment of blame to Bashar al-Assad’s Syrian government.”
The United States and its allies seized on the volume of data in the report to reaffirm their conclusion that only Syrian government forces had the ability to carry out such a strike, calling it a validation of their own long-held assertions.
“This was no cottage-industry use of chemical weapons,” said the British ambassador, Sir Mark Lyall-Grant.