An investigation into the late-November incident concluded that a persistent lack of trust between the US and Pakistan, and a series of communications and coordination errors on both sides, led to the attacks.

Navy Capt. John Kirby, a Pentagon spokesman, said military leaders will use the final report on the investigation to determine if anyone should be punished. Those decisions, he said, would be made by officers in the chain of command, depending on whether they found that mistakes were made by US or NATO personnel.

As a result of the probe, the top US general for the Middle East issued a list of improvements Monday he said must be made to keep similar mistakes from happening. US Marine Gen. James N. Mattis, commander of US Central Command, ordered commanders in Afghanistan to improve coordination of operations along the Afghan-Pakistan border with Pakistani military, and ensure that all border stations are listed correctly on maps.

Mattis also ordered commanders to confirm border post locations before beginning operations along the border. And he ordered commanders to share military practices and procedures with the Pakistanis so they can better understand US operations. It’s not certain the new orders will solve the problems, because Pakistan refused to participate in the investigation.

It still is unclear why Pakistani troops initially fired on US soldiers who had landed by helicopter near a village close to the border as part of a mission to go after insurgents.

The US investigation found that the Pakistani forces fired first and that US troops acted in self-defense.

But US efforts to determine if there were Pakistani forces in the area were foiled by bad maps, poor coordination and Islamabad’s failure to provide the locations of its border posts.

The investigation, headed by Brig. Gen. Stephen Clark, an Air Force special operations officer, found that US forces relying on erroneous maps and poor communications, determined that there were no Pakistani forces or border posts in the area. So they concluded that they were being fired on by insurgents.

US forces also believed that since they had landed in distinctive, noisy Chinook helicopters and fired off warning flares, any friendly forces would have realized that they were shooting at American or NATO troops.

The report also revealed that a US C-130 gunship briefly flew about 3 km into Pakistan airspace during the assault.

Pakistani army spokesman Maj. Gen. Athar Abbas has rejected the US report and insisted that Pakistani forces retaliated only after coalition helicopters “started engagement.” And he denied that Pakistan failed to notify NATO of the location of the two border posts that were attacked.

Pakistani officials have said the report is unlikely to repair the severely damaged relationship between the two countries.

In response to the incident, Pakistan shut down key border supply routes for the Afghanistan war and threw the US out of its Shamsi Air Base in southwestern Balochistan province. The base was used to maintain drones deployed in strikes against insurgents hiding in safe havens in Pakistan’s lawless border region.