MASI KALAY, Afghanistan -- Soldiers of the 82nd Airborne are combing the rugged mountains that border Pakistan in a new U.S. military strategy emphasizing conventional forces rather than elite troops in the search for al-Qaida and Taliban fighters.

In a strong show of force, more than 200 soldiers swept into a number of villages in southeastern Afghanistan on Sunday and uncovered a giant cache of weapons: hundreds of rocket-propelled grenades, thousands of rounds of heavy machine gun ammunition and dozens of mortar rounds.

For months, the military has relied mostly on small special forces units in the region, one of the most active fronts in the U.S.-led hunt for al-Qaida and Taliban. But since August, conventional forces -- mostly drawn from the 82nd Airborne -- began moving from Bagram Air Base, the U.S. military headquarters north of Kabul, and from Kandahar in the south, to bases along the volatile Pakistani border.

Having greater numbers of U.S. troops in the area means a large force can more swiftly move in if al-Qaida and Taliban operatives are encountered, said Col. Martin Schweizter, the commander of the operation. "Being in this particular region right now, we believe it's a target-rich environment," he said.

Sunday's mission began around 1 a.m. as Apache gunships and Blackhawk helicopters carrying the first wave of soldiers from a nearby base swept in low through the rugged mountains. Two companies -- Alpha and Bravo -- of more than 100 men each planned to link up with about two dozen scouts and other support soldiers who had come in on Humvees. The military took a small contingent of journalists on the mission.

The operation got off to a difficult and frustrating start.

As the helicopters carrying Alpha company approached Masi Kalay, between 20 and 30 men were spotted running for the safety of the mountains. All made it.

The first few houses searched by the soldiers yielded little, but at the fourth building, the soldiers found success. The owner, Zahir Shah, told soldiers that weapons and munitions that had been hidden in the village had been moved two days earlier to a hamlet farther south called Golamkhan Kalay, next on the target list.

Dangerous operations

Soldiers there found the first weapons cache of the day -- 200 land mines, a heavy machine gun, more than 100 rounds of heavy machine-gun ammunition, grenades and several rifles. But the search also highlighted the operation's dangers.

As soldiers searched the small hamlet, U.S. forces almost got into a firefight with Pakistani soldiers looking down on them from mountain peaks on their side of the porous border, according to soldiers speaking on condition of anonymity.

The Pakistanis came down from the mountain and told the Americans they had crossed into Pakistan. After a brief confrontation -- each side with guns ready -- the Pakistanis backed off, but not before Schweizter ordered mortar teams to prepare to fire a warning shot and called in air support.

Back at Masi Kalay, Alpha company continued its search as the cool dawn gave way to the heat of the day. The villagers were cooperating, but nothing was found and frustration was mounting.

"There's got to be weapons somewhere in this town," muttered Sgt. Joseph Smith, a 23-year-old from Rapid River, Mich., as he led his squad at about 7 a.m.

Smith was right. About an hour later, another squad was walking past a stone compound when they noticed a locked door. The owner of the compound couldn't produce a key, so Spc. Ben Refroe kicked the door open.

Inside, there were more than a thousand rounds of heavy machine-gun ammunition, 250 rocket-propelled grenades, mortar shells still in their packing, grenades, and land mines.

Finding the cache "felt good. It shows we're doing something over here," Renfroe said. "A lot of the time we don't find a lot ... It's frustrating, you know why you're over here, but sometimes you feel like you're not getting the job done."