U.S. troops could "potentially" aid opposition forces as they descend upon Kandahar, the Taliban's last remaining stronghold, a U.S. Marine officer said Sunday from an Afghan desert base.

"You have a lot of forces at play ... the opposition groups coming from the north down, the southeast up and us potentially coming from where we are," said Maj. James "Beau" Higgins, an intelligence officer.

The seizure of a sand airfield a week ago has allowed the Marines to set up a base within striking distance of Kandahar. The Taliban were facing "a lot of pressure, a kind of snake closing in on them," Higgins said.

Anti-Taliban tribal fighters have been advancing on Kandahar from two directions and are assaulting the nearby airport amid heavy U.S. bombing.

Capt. Stewart Upton, task force spokesman, wouldn’t discuss what role U.S. forces would play in an assault on Kandahar or give any idea of their mission plans, but a 1½-mile-long column of U.S. military vehicles, including light armor, left the base Saturday.

U.S. officials would not say where the vehicles were going.

The Associated Press was allowed to deploy with the Marines on the condition it did not divulge the camp's location or troop strengths, but reports from Washington have said the base is about 70 miles southwest of Kandahar.

A military source who spoke on condition of anonymity said the Taliban were moving forces and weapons to Kandahar from Lashkargah, a town 80 miles west of the city.

Marines held the first religious services at the base on Sunday, a Catholic service followed by a Protestant one, held on a barren patch of dirt.

Higgins conducted the brief Catholic service in lieu of a chaplain for about eight servicemen.

"Marines have that rough and tough exterior," he said afterward. "But everyone has fears."

Meanwhile, the American flags that flew prominently over the base were removed. Capt. David Romley, a spokesman for the Marines, said the flags were raised in the first few days as a symbol of a successful mission but were removed to avoid the impression that the United States intends to stay as an occupation force.

The Marines confirmed for the first time Sunday that several non-American liaison officers were at the base — a packed sand runway and buildings that used to belong to a wealthy Arab who came here for hunting.

"There are British. There are Germans. There are Australians and there are more to come," Upton said.

Though the Marines in Afghanistan did not discuss the implications, the presence of the liaison officers and the fact that more allies were expected could mark the start of a shift in the importance of the coalition.

The effort so far has been almost exclusively American, giving Washington the freedom to make command decisions on its own. British pilots, though, participated in the bombing campaign that began Oct. 7, and about 100 Royal Marines recently were sent to an airfield north of Kabul, the Afghan capital.

U.S. Defense Secretary Donald H. Rumsfeld praised the role of British special forces in Afghanistan in an article published in a British newspaper Sunday.

"American special forces are on the ground, helping the coalition, serving alongside the British special forces — some of the toughest, smartest troops in the world," Rumsfeld wrote in the News of the World. 

Germany, France, Italy, the Netherlands, Canada, Australia, New Zealand, Turkey and Spain have contributed or offered forces.

The role of allies and of any future peacekeeping force is still being worked out. U.S. Secretary of State Colin Powell on Monday begins an eight-day trip during which he will visit several countries that are partners in the campaign.

Helicopters from the 26th Marine Expeditionary Unit, based on the USS Bataan, had been arriving to beef up the task force's air power, Romley said, including quick, heavily armed AH-1W Super Cobra gunships, as well as UH-1N Huey, CH46E Sea Knight and CH-53E Super Stallion helicopters.

Romley said night patrols probing farther and farther from the base had no engagements overnight Saturday.

Asked about the challenges of the operation, Capt. Nevin Marr, who flies a Super Stallion, had a concise answer.

"Dust," said the 28-year-old from Denison, Texas. When a helicopter lands, clouds of dust churn up and envelop the aircraft, making it impossible for the pilot to see the ground.

The Associated Press contributed to this report.