Updated at 5:40 p.m. ET

NEWS BRIEF The Syrian military called off a cease-fire agreement that began last week, a decision it blamed on rebel groups, but which was likely affected by a U.S. bombing mission that killed Syrian government forces over the weekend.

Hours after the cease-fire was declared over, the UN said an aid convoy carrying food and hygiene kits to tens of thousands of people trapped in Aleppo was attacked. Of the 31 trucks in the envoy, 18 were hit, said a UN spokesman Monday. It’s unclear who carried out the attack or the manner in which the convoy was hit.

The UN has not confirmed how many people were killed in the strikes.

On Monday, Syrian officials said rebels used the cease-fire to mobilize fighters and attack government-held positions, according to the Associated Press. The rebels, meanwhile, blamed the Syrian government for violating the agreement, which was supposed to allow aid groups into some besieged towns. It was a quick demise for the cease-fire, brokered by Russia and the U.S.

The first omen of impending failure came Saturday, when the U.S. intended to target Islamic State forces near the Deir ez-Zour airport in eastern Syria, but instead struck more than 60 Syrian government soldiers, injuring another 100. The U.S. apologized, but Russian and Syrian officials questioned if the airstrikes were truly an accident, or part of a plan to prevent the advancement of Syrian troops. The incident came a week after U.S. Secretary of State John Kerry and his Russian counterpart struck a deal in Geneva designed to reduce fighting, give humanitarian aid workers easier access to rebel-held towns, and build trust between the U.S. and Russia.

The two countries are on opposite sides of the Syrian civil war. The U.S. has worked to back rebel forces opposed to the government of President Bashar al-Assad, while Russia is giving Assad military support. Although the cease-fire deal involved the Syrian government and major rebel groups, the agreement excluded ISIS and al-Qaeda linked groups.

Officials from all three countries have used the incident to question each other’s motives.

Syrian officials said the airstrikes were “on purpose and planned in advance” to help ISIS’s mission to overthrow Assad. Russia’s foreign ministry said: “The actions of the coalition pilots—if they were not, as we hope, taken on the instructions from Washington—border on criminal negligence and directly abetting ISIS terrorists.”

It seems part of the confusion that led to the bombing arose from miscommunication between Russian and U.S. Central Command. As The Guardian reported:

Centcom said the coalition had struck the area in the past, and that its members had “earlier informed Russian counterparts of the upcoming strike”.

“It is not uncommon for the Coalition Air Operations Center to confer with Russian officials as a professional courtesy and to deconflict,” the command center said, “although such contact is not required by the current US-Russia Memorandum of Understanding on safety of flight.”

Shortly after news of the airstrike was released, Russian officials called for an emergency closed-door meeting at the United Nations, a move that frustrated the U.S. ambassador to the UN, Samantha Power, who said, “Since 2011, the Assad regime has been intentionally striking civilian targets with horrifying, predictable regularity ... and yet in the face of none of these atrocities has Russia expressed outrage, nor has it demanded investigations, nor has it ever called for a Saturday night emergency consultation in the Security Council.”

The airstrike was carried out by coalition forces, with the aid of Australian aircraft. Officials launched the strike against a supposed ISIS position, which intelligence had been tracking for some time. But the strike underscored just how tricky it has become to coordinate attacks between coalition forces, Russia, Syria, and rebels—each of whom is pursuing their own goals in the region.

For example, in the current system, U.S. and Russia are supposed to notify each other of their respective airstrikes with a quick phone call, sometimes just minutes before a mission. This happened Saturday, as The Wall Street Journal reported, and U.S. officials said they contacted Russia 30 minutes before the strike. The Russians said nothing of Syrian troops in the area until 20 minutes after the bombs dropped when they called back to say the strike had wiped out Syrian soldiers.

By Sunday, the cease-fire was strained further as fighter jets dropped four missiles at opposition neighborhoods near Aleppo, and Syrian forces hit a small village with barrel bombs dropped from helicopters, which killed at least nine people. Syrian presidential adviser Bouthaina Shaaban, said Sunday rebel forces had violated the cease-fire, too.

Then on Monday, the cease-fire was officially called off by the Syrian military.

In the week-long window the cease-fire afforded, the International Committee of the Red Cross said it delivered aid packages to the people of Talbiseh, in Syria’s central Homs province. The AP reported that aid workers managed to deliver 17,000 food parcels to the town of 84,000 people, who have been cut off from any aid since July.