The United Nations resumed aid convoys to besieged communities in Syria on Thursday for the first time since a deadly attack on trucks loaded with supplies Monday.

A 25-truck convoy left Damascus with supplies for 40,000 people in Moadamiya, a suburb of the capital, according to Jan Egeland, a U.N. special adviser for humanitarian affairs. Officials said the convoy had arrived in the afternoon after lengthy delays but without incident.

The United Nations had trucks loaded and ready to leave for other besieged towns before the end of the week, Egeland told reporters in Geneva.

"We seem to be getting the permits and support we need," Egeland said.

The attack on the convoy Monday was the deadliest in the five years of Syria's civil war.