Both Russia and Syria deny any involvement in the convoy attack, which killed 20 civilians. The United Nations suspended all aid convoys pending a security review. The delivery of aid was a key component of the disintegrating cease-fire deal.
Despite the setback, the State Department said it was prepared to extend the cease-fire window in the hopes that if it held, the U.S. and Russia could then turn to their planned military cooperation against the Islamic State militants and al-Qaida-linked groups in Syria.
"Well, the Syrians didn't make the deal," Kerry told reporters in New York. "The Russians made the agreement. So we need to see what the Russians say; but the point, the important thing is, the Russians need to control (Syrian President Bashar) Assad, who evidently is indiscriminately bombing, including of humanitarian convoys. So let's wait and see, collect the facts. We need to see where we are, and then we'll make a judgment. But we don't have all the facts at this point."
An official with the Syrian Red Crescent said aid trucks operated by the group and destined for a rebel-held area in Aleppo province had been hit by an airstrike, as warplanes resumed their bombings in Aleppo province.
Russia took the side of the Syrian government, blaming the rebels for violating the truce. Russia's Foreign Ministry said the failure of Syrian rebels to adhere to the truce "threatens the cease-fire and U.S.-Russian agreements."
The ministry statement came after the Russian military said that continuing rebel violations made it "meaningless" for the Syrian army to respect the deal. The Syrian military said earlier Monday that the cease-fire had expired.
While acknowledging numerous violations, Kirby said the truce, which took effect last Monday, had been responsible for "a measure of reduced violence." However, he also repeated calls for the sustained delivery of humanitarian aid to Aleppo and other besieged communities. Such deliveries began only on Monday and were available only in limited areas, he said.
The United States is outraged by reports that a humanitarian aid convoy was bombed near #Aleppo today. pic.twitter.com/yCurP3rwUV
— John Kirby (@statedeptspox) September 20, 2016
The Syrian military said in a statement Monday that "armed terrorist groups" repeatedly violated the cease-fire and took advantage of the truce to mobilize and arm themselves while attacking government-held areas. The statement said the rebels wasted a "real chance" to stop the bloodshed.
A Syrian activist group said 92 people have been killed in Syria since the start of the cease-fire. The Britain-based Syrian Observatory for Human Rights said 29 children and teenagers were among those killed, as well as 17 women. The figure does not include dozens of Syrian soldiers and Islamic State militants killed in the eastern province of Deir el-Zour, the Observatory said Monday.
A mistaken air raid by the U.S.-led coalition also killed 62 Syrian soldiers.
The opposition reported 254 violations by government forces and their allies since the truce started on Sept. 12, and a senior Syrian opposition official declared the cease-fire "clinically dead."
Syrian state media said there were 32 violations by rebels on Sunday alone.