ISLAMABAD, Pakistan — A U.S. military investigation has blamed poor coordination between American and Pakistani forces for the deaths of 24 Pakistani soldiers in a friendly fire incident along the Afghanistan border in November, the Pentagon said Thursday.

The fatalities outraged Pakistanis and prompted Islamabad to suspend key elements of cooperation with the U.S. combat mission in Afghanistan. Pakistan declined an American invitation to conduct a joint investigation.

"Inadequate coordination by U.S. and Pakistani officers ... resulted in a misunderstanding about the true location of Pakistan military units. This, coupled with other gaps in information about the activities and placement of units from both sides, contributed to the tragic result," the Pentagon said in a statement.

The investigation also determined that Pakistani personnel fired the first shots at the U.S.-Afghan force. Angry Pakistani military officials have denied that assertion in recent weeks, alleging that U.S. forces fired on their personnel without provocation as part of a conspiracy to intimidate Islamabad into dropping its opposition to covert U.S. operations against Afghan insurgents taking refuge in Pakistani tribal regions.

The Pentagon investigation found that there was "no intentional effort" to target the Pakistani military. It vowed to take measures to prevent such an incident from recurring and said it would work with Pakistan to improve deeply strained relations.

"We cannot operate effectively on the (Afghan) border — or in other parts of our relationship — without addressing the fundamental trust still lacking between us," the statement said. "We earnestly hope the Pakistani military will join us in bridging that gap."

The Pentagon expressed "deep regret" at the Pakistani troop losses. But that was unlikely to please Islamabad, which has said that it wants an apology from President Barack Obama himself.

Pakistani officials were noncommittal in their initial reaction to the Pentagon findings. After Prime Minister Yousuf Raza Gilani conferred late Thursday with the foreign minister, Hina Rabbani Khar, a brief statement merely reiterated that a resumption of cooperation with the U.S. would be subject to terms set by Pakistan's parliament.

Speaking to visiting members of Afghanistan's parliament a day earlier, Gilani cited three conditions for a rapprochement: a guarantee that U.S. forces in Afghanistan would respect Pakistan's territorial sovereignty, an end to CIA drone strikes against targets in Pakistan's tribal regions and — in a direct reference to the May 2 U.S. raid that killed Osama bin Laden — a pledge that the U.S. wouldn't launch any unilateral military action in Pakistan.

Of the drone strikes, which are highly controversial in Pakistan, Gilani said they "have caused collateral damage and must be stopped because they are grossly detrimental to the government's efforts to isolate the terrorist from the local population."

Security experts said that Gilani's conditions reflected a desire in Islamabad that the two countries jointly conduct counterterrorism operations, as they had until 2010. U.S. officials, however, are deeply skeptical of Pakistan's willingness and ability to directly confront extremists on its soil.