Bureaucratic delays have held up shipments to troops in Afghanistan through Pakistan, officials said Wednesday, a week after Islamabad reopened U.S. and NATO supply lines.

So far, only a handful of supply trucks have crossed the border, which Pakistan closed to the convoys last November after American airstrikes accidentally killed 24 Pakistani border troops. Islamabad agreed to reopen the supply routes on July 3, after months of negotiations and a U.S. apology over the incident.

Two trucks carrying supplies to U.S. and NATO troops passed through the Chaman border crossing in the southern province of Baluchistan last Thursday. A Pakistani customs official said no other trucks have crossed since then.

Four trucks from the port city of Karachi arrived at the border Wednesday and were expected to cross on Thursday, the official said. Chaman is one of two border crossings used to transport NATO supplies.