ISLAMABAD, Pakistan (CNN) -- The U.S. airstrike which killed 11 Pakistani troops near the Afghan-Pakistan border Tuesday will not interfere with the countries' strategic partnership, Pakistan's U.S. ambassador says.
The U.S. military says the grainy footage shows how its airstrikes targeted fighters engaged with coalition forces.
Ambassador Husain Haqqani, speaking in Washington, said Thursday that the two countries should investigate the "unfortunate incident" together to ensure that it does not happen again, The Associated Press reported.
Pentagon spokesman Geoff Morrell told reporters that there was "every indication" it was "a legitimate strike in defense of our forces after they came under attack."
A U.S. official with knowledge of the incident told CNN the airstrike targeted suspected militants who had fled into Pakistan after conducting an ambush on the Afghan side of the border.
The official said Pakistani military officials worked with the U.S. forces to track the militants as they fled across the border into Pakistan. The official also said the mission was permitted under the rules of engagement, which allow "hot pursuit" across the border of suspected militants when their locations are verified. Watch footage from the drone of the U.S. airstrike »
Meanwhile, Pakistani Foreign Minister Makhdoom Shah Mahmood Qureshi discussed the incident at meeting Thursday with NATO Secretary General Jaap de Hoop Scheffer. The foreign ministry said Scheffer praised Pakistan's contribution to the war against terror.
"He underscored that in this war Pakistan is a part of the solution and this fact is always acknowledged by NATO," Pakistan's foreign ministry said in a statement.
Haqqani said Pakistan remained resolved to fight extremism and terrorism.
"I don't think we can allow such incidents to come in the way of strategic partnership that the United States and Pakistan both need," Haqqani said.
He said Pakistan must know that its partnership with the U.S. was long-term and "that the United States will be there as a friend -- not just today but also tomorrow and the day after."
The U.S. military has released grainy black-and-white aerial footage, recorded by an unmanned drone, that it said depicts the attack on fighters who were battling coalition troops along Afghanistan-Pakistan border. Narration repeatedly notes that there are no military structures or outposts within the impact area.
Yet the video may not provide a complete picture of what happened, the Pentagon conceded Thursday.
The Air Force's official summary of combat action for Tuesday reports a B-1 bomber and two F-15 fighter-bombers dropped laser- and satellite-guided bombs on "anti-coalition members in the open and in buildings in the vicinity of Asadabad."
Pakistan's military said its troops were killed at a Frontier Corps outpost near the border town of Gora Prai, and that the outpost was destroyed in the strike.
Islamabad called it a "completely unprovoked and cowardly act," and the Pakistani government -- a key ally in the U.S.-led war on terrorism -- summoned U.S. ambassador Anne Patterson to protest.