U.S. troops on Wednesday launched a fearsome barrage of artillery and rockets into a mountainous militant stronghold in eastern Afghanistan where they suffered their deadliest combat loss over a year ago.

Plumes of smoke rose over the top of pine tree-forested mountain ranges in Kunar province's Korangal Valley, where scores of troops from the New York-based 10th Mountain Division are trying to curb militant attacks in this volatile region bordering Pakistan.

"We have had nonstop contact for several days and the enemy is on the run," said Staff Sgt. William Wilkinson, 36, of Charlotte, North Carolina, who heads a team firing mortars toward militant positions.

"We have cut them off a couple of times and they are not doing as well as they thought they would."

No militant casualty figures were available from the heavy bombardment of locations some three miles deep into the Korangal Valley, where Al Qaeda and Taliban fighters have set off roadside bombings and staged ambushes targeting American and Afghan forces operating in the region.

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The Korangal Valley was the scene of a June 28, 2005, ambush by militants of a four-man U.S. special forces team, three of whom were killed and the other rescued days later.

A U.S. helicopter sent to find the special forces also crashed in the valley on June 28, killing 16 American troops in the deadliest single attack on the U.S. military since the war began here in 2001.

"This is a place where the Taliban and Al Qaeda have (been) known to roam freely and right now we are putting a stop to that," Wilkinson said.

The echo of cannon fire rumbled through the valley overnight and Wednesday as Howitzers fired round after round of 155 mm artillery shells toward insurgent positions. Tracer fire lit up the nighttime sky and Apaches helicopters fired rockets into hilltop positions.

One target is the Korangali tribe, which is believed to be linked to the Taliban and Al Qaeda and has been sidelined by other tribes in the area for its militant activities, the military said.

Kunar's eastern border abuts the Pakistani tribal region of North Waziristan, which has long provided a safe haven for militants operating in Afghanistan. Al Qaeda fugitives, including leader Usama bin Laden, are believed to be hiding along the porous Afghan-Pakistan frontier.

But on Tuesday, Pakistan's government signed a truce deal with militants they had been battling in North Waziristan since the 2001 U.S.-led invasion of Afghanistan.

Under the deal, tribal leaders in North Waziristan have agreed to ensure the region can't be used as a staging ground for militant attacks on U.S. and Afghan forces across the border, a move that could lead to a reduction in Pakistan-linked violence in Kunar — although skeptics say it may allow militants to operate more freely.

CountryWatch: Afghanistan

Meanwhile, in southern Afghanistan, where NATO-led troops launched an offensive to quash a raging insurgency, one NATO soldier was killed and six others wounded after their patrol strayed into an unmarked minefield, the alliance said.

The soldiers were evacuated to a NATO medical facility after they were taken from the minefield in volatile Helmand province, a statement said. It said the nationality of the dead soldier would be released later, and gave no details about the conditions of the wounded.

Also Wednesday, a suicide bomber blew himself up alongside a car in eastern Afghanistan, killing two passengers and wounding the driver, police said.

The bomber, who was on foot, struck in the Khost province town of Yaqubi. A teacher and a government employee who were inside the vehicle were killed, provincial police chief Mohammed Ayub said.

The motive for the bombing was unclear, but Ayub said the attacker may have confused his victims with another target.