WASHINGTON - The US military has been unable to move any new supply convoys through Pakistan despite a diplomatic breakthrough announced in July that officially reopened border crossings into Afghanistan, a US defence official said.

US military officials have spent the past five months wrangling with the Pakistanis over a formal legal agreement and also working to clear out the roughly 7,000 shipping containers that were stalled in transit when the Pakistanis abruptly closed the border crossings in November 2011.

“It has gone a little bit slower than I thought it was going to go,” said Air Force Colonel Robert Brisson, chief of operations for US Transportation Command, in an interview with Military Times.

Pakistan’s so-called ground lines of communication — known as GLOCs (‘gee-locks’) among military personnel — were the primary supply lines for fuel and once ferried about half of all materiel support for US and NATO troops in Afghanistan. But Pakistan shut down those border crossings more than a year ago after a botched US airstrike killed 24 Pakistani troops in the Afghan border region. The closure forced the US military to abruptly ramp up capacity for the so-called Northern Distribution Network, a complex and costly set of supply lines that run north and west through Russia and Europe.

Currently about 70 per cent of military supplies for Afghanistan come through the Northern Distribution Network, and the remaining 30 per cent is flown in directly via US and NATO aircraft. Rerouting supplies has cost US taxpayers an estimated $70 to $100 million per month. Commanders in Afghanistan say the closures did not impact operations inside Afghanistan.

After about seven months of diplomatic pressure, the Pakistanis agreed to reopen the border crossings in July after Secretary of State Hillary Clinton explicitly apologised for the Pakistani troops’ deaths.

Since then, US and NATO logistics experts have pushed between 10 and 50 cargo trucks across the border per day, a fraction of the estimated 100 vehicles that moved across the border daily before November 2011, Brisson said.

Cargo entering Afghanistan has been limited to the supplies that were stalled in place by the initial closures, which included tons of maintenance supplies and spare parts intended for US and NATO forces as well as the Afghan security forces.

“We haven’t booked any new cargo into the ports of Karachi and Qasim to move northbound, nor have we started moving new cargo heading southbound out of Afghanistan,” Brisson said.

New cargo may begin moving in late December or January, he said.

The US and Pakistani governments still have not reached a final agreement on a key sticking point: how much the US will pay the Pakistanis in shipping tolls for each truck that transits their country, Brisson said.

The toll was reportedly $250 per truck before last year’s closures.

“That level of detail isn’t completely worked out. What the Pakistanis have told us is that there will be no fee increase,” Brisson said.

Getting the supply lines up and running has been slowed by several factors, including some lingering tension between the US and Pakistanis. In addition, US officials want to ensure that “all the I’s are dotted and T’s crossed” because those supply lines will be more important than ever as the US begins a final troop drawdown heading toward the end of the combat mission.

“We want to make sure that we have this clearly ironed out as we start … coming out of Afghanistan to meet the president’s mandate at the end of 2014,” Brisson said. “We want to move a significant portion of retrograde material out of Afghanistan through those Pakistan ground lines of communication. It’s a shorter distance, and it just makes sense.”