US-Pakistani relations are at one of their worst points in memory after the NATO strike that killed 24 Pakistani troops but can recover, Washington's top military officer said on Monday.
General Martin Dempsey said Pakistani anger was justified, given the loss of life on Saturday.
But he declined to offer an apology, saying during a trip to London that he did not know enough yet about the incident and that there was a US military investigation, Reuters reports.
"They have reason to be furious that they have 24 soldiers that are dead, and that the ordinance that killed them was the ordinance of a partner," General Dempsey, chairman of the US military's Joint Chiefs of Staff, told Britain's ITV news.
"I would certainly like to enlist their patience in helping us figure out what happened."
Pakistan's military said the strike was unprovoked, but a Western official and an Afghan security official who both requested anonymity have said NATO troops were responding to fire from the Pakistani side of the Afghan border.
The killings have affected American attempts to ease a crisis in relations with Islamabad, which worsened after the secret US raid into Pakistan to kill al Qaeda leader Osama bin Laden in May this year.
The incident also threatened to undermine US efforts to stabilise the region as Washington tries to wind down the war in Afghanistan.
Pakistan has shut NATO supply routes into Afghanistan in retaliation for the killings.