GENEVA — Syrian military airstrikes on rebels were responsible for severing water supplies to 5.5 million people in the Damascus region for weeks starting last December, the United Nations said on Tuesday, rebutting government claims that insurgents were to blame.
In a bombing campaign to drive rebel forces from the Barada Valley north of Damascus, Syrian air force jets launched multiple strikes on their positions around the al-Feijeh spring, which supplied water to the capital, the United Nations Commission of Inquiry monitoring the conflict in Syria said in a report.
The airstrikes amounted to a war crime, the commission said, because the effect of the attack — denying water to so many people — was “grossly disproportionate” to the military advantage that the government could have anticipated or achieved.
When water supplies to the capital were halted in late December, the government blamed rebels, first saying that they had poisoned the water and later that they had damaged the infrastructure. Water service was not restored until February.
The United Nations investigators said video of the bombings, witness testimony and satellite imagery showed the water supply system had been damaged in at least two airstrikes using high-explosive bombs.
“Public reports that armed groups destroyed the facility with demolition charges are inconsistent with observable physical evidence,” the commission concluded.
The findings came in a report to the Human Rights Council in Geneva that corroborated previously reported accounts by other groups of what they have described as government atrocities in the six-year-old conflict.
The report said government forces had carried out multiple attacks using chlorine bombs, a banned chemical weapon. It also detailed airstrikes by warplanes from Syria on civilian targets.
There was no evidence that aircraft of Syria’s principal ally, Russia, had used chemical weapons, investigators said, but they concluded that Syrian air force or Russian jets had used indiscriminate cluster munitions, which also are banned under an international treaty. The investigators said evidence of cluster bomb attacks had been seen in multiple areas this year.
In one of the deadliest episodes, the commission said Syrian air force jets repeatedly attacked a school complex in the town of Haas in Idlib Province, killing 36 civilians, including 21 children. The attack wounded 114 people, including 61 children.
Humanitarian aid groups have described the Haas attack as one of the most egregious assaults targeting children in the war.
The motive appeared to be to deny any semblance of normal life to civilians living in areas controlled by opposition forces, Paulo Pinheiro, the chairman of the commission, told reporters in Geneva.
Pro-government aircraft also attacked the provincial headquarters of the Syrian Arab Red Crescent in opposition-controlled Idlib Province in February, although its location was well known to the authorities and the building’s roof was clearly marked. The attack destroyed part of the building and its medical unit.
“The attack was most likely perpetrated by either Russian or Syrian aircraft,” the commission said, citing witness testimony, satellite images and forensic evidence gathered from the site.
Opposition forces also inflicted civilian casualties with indiscriminate attacks using mortars and improvised weapons, according to the commission. It found that internal rivalries among opposition forces had led to increasing numbers of summary executions.
The Liwa al-Aqsa group executed 128 fighters from other factions in February, escorting groups of seven to 10 blindfolded prisoners to “repentance lessons” and shooting them in the head or beheading them, the commission said.
The release of the commission’s report punctuated other evidence of unabated suffering and deprivation as the war enters its seventh year. On Sunday, the United Nations Children’s Fund said Syrian children suffered a “drastic escalation” in violence in 2016, with big increases in deaths and combat recruitment.