Their new encampment is remote - more than 60 miles from the nearest ground forces - but Wilson said that serves as an advantage.

"The enemy did not suspect we would come up here. They believe they have a safe haven area up here because it has been untouched by coalition troops for years," he said.

Once down on the mountain ridge, soldiers went to work setting up defense positions and firing mortar rounds into the valleys to test their equipment and check ranges.

Standing guard with an M-16 rifle on a ridge line, Spc. Daniel Borisow, 23, from Akron, N.Y., looked down into the valley at a smattering of mud huts. He said he was ready to fight.

"For once we are in the position where we're going to take the fight to the enemy instead of us rolling through (in Humvees) and them attacking us," he said.

The open-ended offensive aims to hunt down Taliban fighters blamed for an onslaught of ambushes and bombings in recent months, the worst spate of militant violence since 2001.

More than 500 people - most of them militants - have been killed in the past month as insurgents launched increasingly bold attacks on coalition forces. More than 90 suspected militants have been killed the past few days, the coalition says.

At least nine coalition soldiers have been killed since mid-May.

On Sunday, Taliban militants fatally shot a former chief of one of Helmand province's districts and four of his bodyguards in an ambush of their convoy, provincial spokesman Ghulam Mohiudin said. The official, Jama Gul, was traveling between Sangin and Grishk districts.

Southern Helmand was also the scene of fighting Saturday, when British troops killed six Taliban fighters near Kajaki dam, a British spokesman, Capt. Drew Gibson, reported Sunday.

Militants had been firing mortars the past few day in an attempt to damage the dam, and British forces "tightened security in this area," Gibson said.

In nearby Zabul province, a joint operation between police and coalition soldiers in Shahjoy district killed two suspected militants. Two other wounded insurgents were captured, said the provincial police chief, Noor Mohammed Paktin.