The United States has apologised for a NATO helicopter attack inside the border of Pakistan last week that killed at least two Pakistani soldiers and provoked the fury of the government in Islamabad.
After the incident, Pakistan closed a key border crossing used by NATO for supply convoys to Afghanistan.
US envoy to Pakistan Anne Patterson said on Wednesday that her country offered its deepest apology, while General David Petraeus vowed to work to stop similar incidents happening in the future.
NATO admitted its two helicopters had entered Pakistani airspace and opened fire on the border guards.
The incident, on 30 September, infuriated public opinion in Pakistan and led to anti-NATO demonstrations.
The government closed a border crossing used by NATO to supply forces in Afghanistan a day after the attack.
The BBC reports the border closure has led to long queues of traffic and increased attacks on fuel tankers heading for NATO bases.