CHECKPOINT PEROZI, Afghanistan -- U.S. soldiers who rotate through this checkpoint in Panjwai District sleep on cots that line the narrow confines of a thick-mud-walled hut where farmers once used to dry grapes. To guard against attack from insurgents, they take turns posting watch on a rooftop that overlooks a village in this traditional homeland of the Taliban.

Their view takes in a nearby field where a young soldier died in a spring ambush just weeks after their unit -- the 1st Battalion 23rd Infantry Regiment -- arrived from Western Washington's Joint Base Lewis-McChord.

The village skyline is dominated by a fortresslike compound where a lieutenant stepped on an improvised explosive device that blew off his foot.

In recent weeks, U.S. Army commanders have decided to beef up security here in response to another potential threat: Afghan police who occupy the housing in an adjacent courtyard and join U.S. forces on patrols into the village.

"The generals want everyone here to watch those guys," said Pfc. Matthew Brown, a young soldier in Blackhawk Company. "We not only have to guard outside the wire, but now we have to look after our back door as well."

This tighter scrutiny of Afghan forces reflects Pentagon concerns over the growing threat of Afghan allies turning against U.S. forces. These insider killings have killed more than 50 western troops this year, including a September assault at a checkpoint north of here that claimed the lives of three Lewis-McChord soldiers.

The restrictions are a troubling new aspect of the war.

There is increased uncertainty about who is friend and who is foe, and what will happen to security gains once the NATO troops cede combat duties to Afghan forces in late 2014.

The strategy for winding down the war faces one of its toughest tests here in Panjwai, an area of strategic importance to the Taliban, who use the cover of trees and foliage to move arms, explosives and fighters to other areas of southern Afghanistan.

"In their minds, if they can't hold Panjwai ... they can't hold anywhere," said U.S. Gen. Robert Abrams, who leads NATO's regional southern command. "That's why we have to fight so hard for it."

1st Battalion leaders say they have been able to pressure the Taliban by arresting some of the ringleaders of bomb-making networks and cracking down on insurgent supply lines.

To try to protect such gains after 2014, the Pentagon plans for an "enduring presence" of U.S. advisers, Special Forces, air support and other assets, the cost of which has yet to be estimated.

But in Panjwai, even with the current level of forces and spending, hostile places remain, including the village just outside of Checkpoint Perozi.

"We clear something and pull back out, and then they (insurgents) reinhabit it," said Pfc. Chris Engelke, a soldier from California who took his turn on rooftop watch.

"We never keep things clear ... I guarantee you that if we were to walk down that road we would get shot at or find an IED."

An Afghan National Army captain in Panjwai is skeptical that his force will be able to withstand the Taliban after U.S. combat troops withdraw.

"Right now we have helicopters. We have (surveillance) balloons and everything, and you see still what is going on," said Capt. Habibullah Noorzi. "If America is not here, there is going to be killing and destruction. Not only in Panjwai, but other districts and Kandahar City. The Taliban will be coming."

Always on guard

Within Panjwai District, there hasn't been an incident of Afghan forces attacking NATO troops.

But U.S. forces are constantly on guard.

When an unarmed Afghan soldier ventures from his side of a combat outpost to visit a medic on the American side, he is flanked on both sides by armed U.S. solders, an escort worthy of a prisoner.

Even Afghan officers can't escape an armed escort as they head into talks with their U.S. counterparts.

Such security measures, though awkward, have not unraveled the partnerships that some U.S. soldiers here have forged with Afghan National Army forces.

On a recent patrol, Afghan soldiers appeared poised and professional as they carefully navigated a path through a route notorious for IEDs.

But the Afghan soldiers were far outnumbered by U.S. troops, who used mine-sweeping equipment to find a safe route. This patrol was backed up by U.S. air power -- two Kiowa helicopters called in to fire hundreds of rounds of 50-caliber bullets and eight rockets at insurgents trying to stage an ambush.

That overnight mission was abruptly cut short as word came down from NATO commanders about a temporary halt of joint operations to reassess security.

After a noon lunch break, the U.S. soldiers apologized as they shook hands with their Afghan counterparts, and bid them farewell.

"You guys are not the problem," said Staff Sgt. Kelly Rogne, a Lewis-McChord soldier from Colville, Stevens County.

"We are great friends. We work well together. You are friends. Don't think that we're going to shoot you," said an Afghan sergeant.

Among U.S. soldiers in Panjwai, there appears to be more mistrust of another important element of the Afghan forces: the Afghan National Civil Order Police.

At Checkpoint Perozi, U.S. forces had hoped the police would take over staffing, and free up American soldiers for other missions. But the Afghans have balked at staying alone at the checkpoint.

As U.S. soldiers rousted themselves after another night in the Perozi grape hut, the scent of marijuana came wafting through the air from the Afghan side of the compound, where the police were smoking in a frequent morning ritual.

U.S. soldiers say that the police don't show much interest in patrols, and earlier in the year an interpreter was killed by an IED set off by a an Afghan policeman who wandered off a cleared path.

"They really don't do very much. If anything, they are a hassle," said Pfc. Brown. "To be honest, I would rather just go out without them."