On the Af-Pak border, the U.S. military grinds on

The American military continues to fight on in Iraq and Afghanistan, and the casualties continue to mount.

CBS News correspondent Mandy Clark embedded with the 101st Airborne in Paktika province, Afghanistan, recently. They are right on the border with Pakistan. The troops there face a tough trying to stop the enemy from crossing into Afghanistan from their hideouts in Pakistan.

One group from the 101st, Fox Company, headed out at dawn on Saturday. Their mission: to cut the enemy off at the source - along the border with Pakistan, the razor's edge of the war. The pilots struggled to land the helicopters on the rugged mountaintop. Soldiers rushed out and took up defensive positions.

In the harsh mountains where they're patrolling, the air is thin and visibility is limited. This is the insurgents' backyard.

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First Lieutenant Sean McCune told CBS News: "There is a large number of insurgents that use this as a bed-down area, so we suspect that they are using it as a training camp as well."

McCune is the leader of second platoon. He and his men were moving fast and using cover to try and sneak up on the insurgents. They succeeded.

Three armed men, possibly enemy spotters, were identified on the next ridge. The response was swift and fierce. Two 500-pound bombs were dropped right on the border with Pakistan. Three dead bodies were later recovered, along with heavy weapons and communication equipment.

Fox Company pushed on, hoping to flush the enemy out. Company commander Captain Christopher Tanner, a West Point graduate from Alabama, was waiting for his men to gather on a ridge when rockets started raining in.

He called in counter-fire. Within minutes he had close air support, and back at the base heavy guns opened up.

There was no way of knowing if the shells had found their targets. The soldiers were just hoping to learn where the enemy was shooting from.

Late into Saturday night, Tanner waited for the enemy to reveal itself, but the insurgents chose to wait and fight another day.

Early Monday morning, Fox Company was picked up, and Tanner was satisfied.

"Every fighter we stop here on the border is one less fighter that makes it into the heart of Afghanistan," Tanner said.

This mission was a success, if only because every one of the members of Fox Company came back safely. But the battle continues. While they were away, their base, FOB Boris, has taken indirect fire and all day, while their heavy guns were lobbing shells at far away targets.