Both Russia and Assad deny bombing a UN aid convoy in Syria

A UN aid convoy delivering food and supplies to a rebel-held town in northern Syria was targeted in an airstrike late Monday as a week-old ceasefire, negotiated by the United States and Russia, spectacularly collapsed.

A barrage of bombs rained down on the convoy of 31 trucks, belonging to the Syrian Arab Red Crescent, as it unloaded food parcels in the rural area of Urem al-Kubra. All of the trucks were clearly marked and their route had previously been shared with all parties to the Syrian conflict.

12 people were killed in the attack, according to the Syrian Observatory of Human Rights; most of them were drivers. The UN confirms that least 18 of the convoy's 31 trucks were hit, in addition to a warehouse.

It has yet to be confirmed whether the trucks were shelled or bombed. But the bigger uncertainty is that no one has claimed responsibility.

The head of the UN's relief organization, Stephen O'Brien, said he was "disgusted" by reports of the assault. He also warned that if the aid workers were purposefully targeted, the day's tragedy would amount to a war crime.

Disgusted an aid convoy was hit this eve in Urum al-Kubra — Stephen O'Brien (@UNReliefChief)September 19, 2016

Just hours after the attack, the US State Department accused Russia of failing to uphold its ceasefire duties and of failing to inspire restraint in Damascus — though US officials did not directly accuse Russian planes of carrying out the bombardment. In a statement, the State Department vowed to "reassess the future prospects for cooperation with Russia" in Syria.

US officials also reiterated their desire to extend the ceasefire, and called on the Russians "to use their influence on Assad to these ends."

Speaking from New York on Monday, US Secretary of State John Kerry was less circumspect. "The important thing is that the Russians need to control Assad, who evidently is indiscriminately bombing," he said.

Inter-agency convoy is crossing the conflict line to Big Orem in — OCHA Syria (@OCHA_Syria)September 19, 2016

The State Department also lay blame on the Assad regime, which it claims has "repeatedly denied entry to these UN convoys, preventing them from delivering urgent food, water and medical supplies to desperate Syrian citizens."

Russia denied that its warplanes conducted the airstrike and Syria also denied responsibility.

The United States is outraged by reports that a humanitarian aid convoy was bombed near — John Kirby (@statedeptspox)September 20, 2016

The ceasefire in question had been in place since Sept. 12, at sundown, and was designed to facilitate the delivery of humanitarian aid. It held for seven days. At the time of the convoy attack, no party to the ceasefire had officially declared it over.

But even while the ceasefire was in effect, minor violations occurred and humanitarian deliveries were delayed on security grounds. Western officials accused the Syrian regime of repeatedly breaking the terms of the peace. And on Monday, the Syrian army issued a statement blaming "terrorist groups" for hundreds of alleged ceasefire infractions.

Airstrikes also continue in and around Aleppo, the besieged and opposition-controlled town of a quarter million people.

On Saturday, the US-led an airstrike against Syria army forces which killed 62 Syrian soldiers and injured around 100. American officials later apologised for the incident and described the attack as accidental: meant to target the Islamic State's frontline, not the Syrian regime.

The Syrian government, however, accused the western coalition forces of bombing the party "on purpose."

Shortly before the UN convoy bombardment, US Secretary of State John Kerry described deliveries of food under the ceasefire as a sign of progress — and a step towards peace in Syria.