ISLAMABAD The U.S. ambassador to Islamabad apologized to Pakistan on Wednesday for a NATO incursion in which U.S. helicopters killed two Pakistani soldiers, saying it was a "terrible accident."
Am embassy statement said a joint investigation showed U.S. helicopters had mistaken the soldiers for insurgents they had been pursuing.
The apology was made by U.S. Ambassador Anne Patterson.
The September 30 helicopter strike was the most serious of recent cross-border incidents involving NATO-led forces fighting in Afghanistan, which have stoked tensions with neighboring Pakistan.
Pakistan shut a vital supply route for NATO forces fighting in Afghanistan after the strike, officially citing security reasons.
U.S. pressure on Pakistan to crack down harder on militants in its northwest tribal areas has been one source of friction between the two countries.
The United States has also ramped up a covert campaign of drone strikes against insurgent targets within Pakistan's borders.
(Reporting by Kamran Haider; Writing by Michael Georgy; Editing by Charles Dick)