Syrian military helicopters systematically dumped canisters of chlorine gas, a banned weapon, on residential areas of Aleppo at least eight times late last year in the final weeks of the battle to retake the city from rebels, Human Rights Watch said in a study released Monday.
The assertions in the study, if confirmed, would represent one of the most egregious uses of such outlawed weaponry in the war. Under an international treaty the government signed more than three years ago, Syrian President Bashar Assad promised to never use chemical arms.
A United Nations panel that has been investigating reports of chlorine bombs and other chemical weapons in the Syrian war concluded last year that government forces had used them at least three times in 2014 and 2015. The panel is scheduled to provide an update this month.
Assad and his subordinates have repeatedly denied that their side has ever used chemical weapons, calling the evidence fabricated or inconclusive.
[TIMELINE: Key events in Aleppo since the start of Syria’s uprising ]
But the Human Rights Watch report suggested that Syrian officials had not only disregarded the U.N. findings but also had decided to use chlorine bombs far more aggressively in the Aleppo campaign.
The report relied on interviews with emergency medical workers and other witnesses, photographs that appear to show spent gas canisters, and analyses of video. The report acknowledged that "identifying with certainty the chemical used in the attacks without laboratory testing is difficult."
There had been unverified accounts of haphazard chlorine bomb use in Aleppo, the northern Syrian city that became the focal point of the war in November and December. But the report's conclusions pointed to a calculated government plan to use the poison to either kill inhabitants of contested neighborhoods or drive them out.
"The pattern of the chlorine attacks shows that they were coordinated with the overall military strategy for retaking Aleppo, not the work of a few rogue elements," Ole Solvang, deputy emergencies director at Human Rights Watch, said in releasing the report.
In all eight instances in which the group concluded chlorine bombs had been used, the report said they were dropped in areas where government forces had planned to advance. The report said the attacks, from Nov. 17 to Dec. 13, killed at least nine civilians, including four children, and hurt 200.
Chlorine, a common industrial chemical that can be fatally toxic, is not by itself illegal. But the Chemical Weapons Convention, the treaty that outlaws such arms, forbids the use of toxins to kill or injure.
The report said there had been no evidence that Russian military forces, which helped Assad's side retake Aleppo, were directly involved in any chlorine bomb attacks. Nonetheless, the report said, "as a military ally of Damascus, it benefited from the use of chemical weapons by Syria forces."
Russia, which helped pressure Assad's government to sign the Chemical Weapons Convention in 2013, has denounced any use of such weapons and voted with the United States and other U.N. Security Council members to ensure accountability if they were used in Syria.
Solvang exhorted the Security Council not to "let Syrian authorities or anyone else who has used chemical weapons get away without consequences."
Separately, the Russian Defense Ministry released new video footage showing the partial destruction of the ancient Roman amphitheater in Palmyra.
The footage, shot from a drone, also showed the destruction of the city's tetrapylon, an arrangement of 16 columns marking the city's main crossroads.
Control over Palmyra has passed back and forth. Islamic State fighters first captured the city in 2015. In March 2016, the city was retaken by Syrian forces backed by Russian air power and special forces.
Then, with Russian and Syrian forces focused on Aleppo, the Islamic State retook control of Palmyra in mid-December.
The Russian Defense Ministry also said Islamic State fighters were planning to destroy more monuments before abandoning the city, claiming it was a response to an expected offensive by the Syrian army. "This shows ISIS's intentions to deliver explosives in order to totally destroy the remaining ancient architectural monuments before their retreat," it said in a caption accompanying the video, using an acronym for the Islamic State.
No visual evidence was given to support that claim.
Irina Bokova, head of UNESCO, condemned the latest demolitions as a "war crime."
Information for this article was contributed by Rick Gladstone, Sergio Pecanha and Tim Wallace of The New York Times; and by Andrew Roth of The Washington Post.
A Section on 02/14/2017