The US has apologised for a recent helicopter attack that killed two Pakistani soldiers at an outpost near the Afghan border, saying American pilots mistook the soldiers for insurgents they were pursuing.
The apology, which came after a joint investigation, could pave the way for Pakistan to reopen a key border crossing that Nato uses to ship goods into landlocked Afghanistan. Pakistan closed the crossing to Nato supply convoys in apparent reaction to last month's incident.
Suspected militants have taken advantage of the impasse to launch attacks against stranded or rerouted trucks, including two on Wednesday where gunmen torched at least 55 fuel tankers and killed a driver.
"We extend our deepest apology to Pakistan and the families of the Frontier Scouts who were killed and injured," said US ambassador to Pakistan Anne Patterson.
Pakistan initially reported that three soldiers were killed and three wounded in the attack, but one of the soldiers who was critically injured and initially reported dead ended up surviving, said Major Fazlur Rehman, a spokesman for the Frontier Corps.
Pakistani soldiers fired at the two US helicopters prior to the attack, a move the investigation team said was likely meant to notify the aircraft of their presence after they passed into Pakistani airspace several times.
"We believe the Pakistani border guard was simply firing warning shots after hearing the nearby engagement and hearing the helicopters flying nearby," said US Air Force Brigadier General Tim Zadalis, Nato's director for air plans in Afghanistan who led the investigation. "This tragic event could have been avoided with better coalition force coordination with the Pakistan military."
The head of US and Nato forces in Afghanistan, General David Petraeus, also expressed his condolences, saying in a statement that "we deeply regret this tragic loss of life and will continue to work with the Pakistan military and government to ensure this doesn't happen again."
Pakistan moved swiftly after the attack to close the Torkham border crossing that connects north-western Pakistan with Afghanistan through the famed Khyber Pass. The closure has left hundreds of trucks stranded alongside the country's highways and bottlenecked traffic heading to the one route into Afghanistan from the south that has remained open.
There have been seven attacks on Nato supply convoys since Pakistan closed Torkham, including those on Wednesday. Nato officials have insisted that neither the attacks nor the border closure have caused supply problems for Nato troops since hundreds of trucks still cross into Afghanistan each day through the Chaman crossing in south-western Pakistan and via Central Asian states.