NEW YORK — Russia was probably responsible for the deadly bombing of a United Nations humanitarian aid convoy in Syria, US officials said Tuesday, further shredding what remained of a severely weakened agreement between the United States and Russia aimed at halting the war.
Aghast at the attack on Monday night, UN officials on Tuesday suspended all aid convoys in Syria, describing the bombing as a possible war crime and a cowardly act.
Publicly, the Obama administration said it held Russia responsible, in its role as a sponsor of the cease-fire agreement that it reached last week with United States. But the Americans still held out the possibility of salvaging the agreement. Benjamin Rhodes, the deputy national security adviser, said Russia should have ensured a halt to air operations in an area where “humanitarian assistance is flowing.’’
Privately, US officials said their intelligence information suggested Russian aircraft had actually carried out the attack.
The US officials said the Obama administration wanted to allow Moscow the time and space to investigate and announce its own conclusions about the bombing, which destroyed 18 of 31 trucks authorized to travel to a rebel-held area in northern Syria.
The bombing was the second disaster in three days to subvert the agreement between Russia and the United States, which had called for a weeklong cease-fire, humanitarian aid deliveries, collaboration by the two powers on targeting militant extremists in Syria, and a buildup of trust to eventually resume peace talks.
On Saturday, an errant US airstrike that was supposed to target Islamic State militants in Syria instead killed 60 people that Syria’s government and its Russian allies identified as Syrian soldiers; both Syria and Russia suggested that the assault was deliberate, despite US apologies.
The United States has the ability to track warplanes and other aircraft in the region through radar and other sensors.
The Pentagon has determined with “very high probability’’ that a Russian Su-24 attack plane was directly over the aid convoy less than a minute before the airstrike was reported, a senior US official said.
“We have a very good picture of the skies over Syria, as well where there’s activity,’’ the official said. “We know the plane in question was Russian, not Syrian, and was directly overhead.’’
US analysts are assessing photographs of the bomb damage that could be tied to the weapons the Su-24 carries. They are also checking for any intercepted communications from the Russian pilot to determine why the convoy was struck.
“We have no indication that anything other than Russian tactical aircraft were in the air at the time the convoy was struck, to include both strike and reconnaissance aircraft,’’ said another US official. “We have seen no indication that it was anything other than an airstrike.’’
The officials spoke on condition of anonymity because they were discussing classified intelligence information.
Colonel John J. Thomas, a spokesman for US Central Command, said at the Pentagon on Tuesday that warplanes of the US-led coalition that is fighting the Islamic State in Iraq and Syria had not carried out the attack.
The strike on the trucks, which were carrying critically needed food and medical supplies bound for rebel-held areas of Syria’s western Aleppo province, took place shortly after the Syrian military declared that it regarded the seven-day partial cease-fire as over.
