KABUL, Afghanistan - U.S. helicopters flew Afghan troops into a remote northeastern district overrun by the Taliban and recaptured the main town Tuesday without firing a shot, military officials said.

Afghan officials said they were preparing for a counterstrike by the insurgents, who often melt away in the face of overwhelming force and later try to infiltrate areas under government control.

A unit of about 200 elite Afghan troops landed in the Barg-e-Matal district of Nuristan province before dawn in an assault backed by U.S. helicopters and a handful of American advisers, U.S. officers familiar with the operation said.

They recaptured the main town in the region without shooting, and no one was harmed, NATO said in a statement, though the operation was expected to continue for a few days. Taliban fighters were believed to have left the town and may have taken positions elsewhere in the valley.

Nuristan's police chief, Gen. Mohammad Qasim, said Afghan forces had rebased themselves in police and government buildings in Barg-e-Matal and were preparing for a possible counterstrike by insurgents.

"We are ready, and we have the support of [NATO] air forces," he said around nightfall Tuesday.

He said that 54 insurgents were killed or wounded in fighting and air strikes before Tuesday's operation began and that two police also died.

Government forces pulled out of the mountainous region last weekend after hundreds of Taliban fighters swept in from nearby Pakistan and fought for almost a week with Afghan troops and local residents, who have a reputation for fierce resistance to outsiders.

U.S. troops had established an outpost in Nuristan but abandoned it in October after eight American soldiers were killed in a fierce Taliban attack. Insurgent strength has grown in the region since, prompting fears that Taliban who have come under pressure from U.S. missile strikes and military operations in Pakistan could be looking for a new haven.

The U.S. officers said Taliban fighters - mostly Afghans but also Pakistanis and a few Arabs - are thought to number about 500.

Villagers reported that a senior Pakistani Taliban commander, Maluana Fazlullah, was killed in fighting with Afghan troops in Nuristan last week, but officials have not been able to confirm it.