Hundreds of insurgents raided a pair of remote military outposts in Afghanistan, killing eight U.S. soldiers and capturing at least 20 Afghan security troops in the deadliest attack on U.S. forces in more than a year.

U.S. media are referring to the incident as the "Black Hawk Down" of Afghanistan, as 48 U.S. troops and 25 Afghan soldiers were outnumbered at least three to one in a fierce gunbattle.

The battle broke out at dawn Saturday in Nuristan province, near the Pakistan border, and went on throughout the day.

The heavy loss of life comes at the same time as Washington is looking at changing its direction in the war, now into its eighth year.

Gen. Stanley McChrystal, the top U.S. and NATO commander in Afghanistan, is planning to shift soldiers away from difficult to defend remote outposts and towards more heavily populated areas, with the aim of protecting civilians.

"We don't have enough forces to do everything, everywhere at once," he said.

One of the bases attacked on Saturday was due to be closed within days, ABC News has reported.

U.S. forces used helicopters, heavy artillery, airstrikes in the battle, and caused "heavy enemy casualties," a NATO statement said.

"This was a complex attack in a difficult area," U.S. Col. Randy George, the area commander, said in a statement. "Both the U.S. and Afghan soldiers fought bravely together."

The Taliban have claimed responsibility for the attack, but NATO says that some of the attackers were mix of "tribal militias." -- Taliban and fighters loyal to Sirajudin Haqqani, an Al Qaeda-linked militant.

Provincial police chief Mohammad Qasim Jangulbagh estimated about 300 insurgents were involved in the attack.

As of Sunday, 804 American soldiers have died in Afghanistan.

McChrystal has said he wants another 40,000 soldiers for the country, but both politicians and the American public are increasingly growing weary of the mission.

U.S. President Barack Obama is expected to make a decision on a new strategy for Afghanistan in the coming weeks.