GARDEZ, Afghanistan ? Tanks and trucks carried 1,000 more U.S.-allied Afghan fighters to the remote mountains of eastern Afghanistan on Monday to reinforce American troops closing in on al-Qaida and Taliban holdouts.

In preparation for a final push, high-flying U.S. B-1 bombers pounded remaining enemy positions on a ridgeline known to U.S. troops as “the whale” in the frigid Shah-e-Kot mountains. U.S. special forces were seen moving nearby as clouds of dark smoke rose from the impact of the bombs.

Defense Secretary Donald Rumsfeld, speaking on the steps of the Pentagon, said he hoped allied forces would finish “mopping up” the area by week’s end.

Afghan commander Mohammed Ismail Khan estimated that three-fourths of the enemy force, once said to number about 1,000 fighters, had been killed.

As ground fighting subsided, hundreds of U.S. troops from the 10th Mountain Division and the 101st Airborne Division rotated back to Bagram air base north of Kabul.

Several Chinook helicopters set down Monday at the base, in the shadow of the towering Hindu Kush mountain range, disgorging muddy, weary soldiers from the front lines.

Rumsfeld said there were still more than 800 U.S. soldiers operating in the 60-square-mile Shah-e-Kot Valley.

“The al-Qaida and Taliban extremists seem to be in much smaller pockets now  not the larger groups that we saw the first few days,” said Maj. Bryan Hilferty, a spokesman for the 10th Mountain Division. “We will continue to work our way through the area until we are satisfied we have taken out all of the al-Qaida terrorists.”

Hilferty refused to say whether U.S. special forces had entered any more of the mountain caves used by Taliban and al-Qaida fighters. Khan, the Afghan commander, said none of the major caves where enemy fighters were believed hiding had been breached Monday.