U.S. officials suspect a sniper was responsible for wounding an American soldier in southern Afghanistan, where U.S. troops have come under attack several times in recent weeks.

But the shooting of Sgt. 1st Class Roderick Morgan and other recent attacks were not enough to suggest snipers are a growing problem for U.S. troops in Afghanistan, military spokesman Col. Roger King said Thursday.

Morgan, of the 82nd Airborne Division, was hit late Tuesday while on patrol in an area about 5 miles north of Kandahar's air base. The bullet struck his protective Kevlar helmet and glanced off, Col. Roger King said.

Although the helmet stopped the bullet, the impact gave Morgan a concussion, U.S. officials said. He was flown to Bagram air base, the U.S. headquarters for the war in Afghanistan, where he was being treated. Morgan was expected to return to duty in a few days.

The Kandahar airfield is the base for a contingent of U.S. special forces and other troops who have been hunting Al Qaeda and Taliban remnants following the hardline Islamic militia's ouster last year. Kandahar was the Taliban's stronghold and the last major city they abandoned.

U.S. officials believe hundreds of fighters have sought refuge in the tribal regions of southeastern Afghanistan.

U.S. patrols have had few encounters with Taliban or Al Qaeda, but have found stockpiles of weapons and ammunition believed to have been left behind by anti-U.S. fighters.

American forces have come under sporadic attack in the region.

On July 2, a U.S. military convoy was fired on as American forces returned from the hospital where victims of a U.S. air attack were undergoing treatment. One solider was shot in the foot. It was not known who opened fire.

In the past three weeks, U.S. special forces in the town of Khost near the Pakistani border have come under rocket fire at least three times.

It was not known if Al Qaeda, the Taliban, local warlords or individuals acting alone are responsible for the attacks, King said.

King said he did not believe the rocket fire reflected a "stepped up level of violence" against U.S. forces in the region, and that he had not heard of sniper fire being directed at U.S. forces prior to Morgan's case.

He said that U.S. forces did not return fire Tuesday night because they did not hear the shot that hit Morgan, and therefore could not determine where it came from. Morgan was walking between two vehicles when the bullet hit him, King said.

"There were no shots heard," King said. "That's why it's suspected fire. If you don't hear fire its hard to react to fire other than recovering your wounded and removing yourself from the area."

Tension between U.S. forces and Afghans in central Afghanistan rose last week after a U.S. gunship opened fire on several villages in Uruzgan province. Afghan officials said 48 civilians were killed and 117 wounded.

President Bush telephoned Afghan President Hamid Karzai to express condolences for the civilian deaths in the July 1 attack. A formal investigation has been announced to determine its cause.

Leaders in Uruzgan, which like southern Afghanistan is a predominantly ethnic Pashtun region, said Afghans were outraged at the civilian killings and warned that they could spur people to begin fighting Americans.