Five Marine Corps attack helicopters entered the fight in eastern Afghanistan on Tuesday, supplementing an aerial assault force depleted by damage to Army Apache attack helicopters, Pentagon officials said.

A number of AH-64 Apaches took extensive fire from small arms Monday in battles south of the city of Gardez. The Apaches completed their missions and none was shot down, but an undetermined number sustained enough damage from ground fire to require repairs, the officials said.

The Marine AH-1W Cobra attack helicopters were ordered into battle after moving from the USS Bonhomme Richard in the North Arabian Sea to a base inside Afghanistan, the officials said, speaking on condition of anonymity. Moving with the Cobras to Afghanistan were two CH-53E Super Stallion transport helicopters.

The Cobra, with a crew of two, is armed with a 20mm cannon and can fire a wide variety of precision guided missiles, including Hellfire and TOW anti-armor missiles and Sidewinder anti-air missiles.

Threats to U.S. interests extend beyond the battle in Gardez. U.S. intelligence has learned of a plot to conduct multiple car bombings in Kabul, against both Western interests and the interim Afghan government headed by Hamid Karzai, a U.S. official said, who spoke on condition of anonymity.

They were to have been carried out by terrorist cells with links to Al Qaeda, the official said. It was unclear what became of the plot.

U.S. troops have detained four people during the latest operation, Pentagon spokeswoman Victoria Clarke said. Another man was detained and released, Clarke said.

Military officials offered no further information about the detainees. They have described those fighting U.S. troops as mostly non-Afghan Al Qaeda and Taliban members, possibly including Arabs, Chechens and Pakistanis. An identification card from Saudi Arabia and a hotel receipt from Iran were found in an area abandoned by the fighters.

At the Pentagon, officials showed the first gun-camera video of airstrikes in the U.S. offensive, dubbed Operation Anaconda, which began last Friday. It showed two Air Force F-16 fighter strikes Sunday against dug-in enemy positions in the mountainous terrain, where U.S. and allied forces are battling hundreds of fighters from the Al Qaeda terror network and the former ruling Taliban militia. Also shown was footage of a strike Monday by a Navy F-14 fighter against an enemy mortar position.

The Pentagon also released combat video of movements on the ground by members of the 101st Airborne Division.

Air Force Brig. Gen. John Rosa, deputy director of operations for the Joint Chiefs of Staff, told reporters that the U.S. offensive was making progress.

"I would say we are softening up in certain portions, but there's still a lot of work to be done," he said. "We're far from over."