SARKONI DISTRICT, Afghanistan — Capt. Floy Rodriguez, leader of a U.S. Marine advisory team to the Afghan National Army, was listening to Johnny Cash at a forward operating base deep in the arid mountains of northeast Afghanistan when a group of about 30 insurgent fighters attacked last month with rocket-propelled grenades and machine-guns.

The base, called Lumberyard, had been established in early May as a foothold for Afghan and U.S. troops pushing north into Kunar and Nuristan provinces. The attack, and the killing of a local informant whose information could have prevented it, typify the difficulties faced by U.S. and Afghan forces as they push farther into this rugged corner of Afghanistan, often mentioned as a possible hiding place of top al-Qaida figures.

As coalition forces move into remote insurgent havens, they have been unable to provide security locals say they need in order to help oust insurgents completely. Villagers who do help coalition forces suffer, or die, for it. "Whoever shows up with guns on that day, the villagers are that guy's friend," says Rodriguez, who spent more than a month patrolling the area with Afghan soldiers and meeting with villagers both inside and outside Lumberyard.

Those patrols were too short and too spread out to secure the valley, which remains full of "bad guys," he says. The inability to provide security for villagers in these areas hampers the long-term effectiveness of operations, such as Mountain Thrust, a large-scale coalition offensive launched recently in southern Afghanistan following an upswing in insurgent activity there.

Insurgents hold sway in parts of the countryside surrounding operating bases in the southern provinces. In lieu of securing whole areas like those in the southern deserts or northeastern mountains, the United States has set up bases like Lumberyard from which it conducts patrols, meets with village elders and constantly travels the roads in search of bombs.

And while coalition soldiers are able to glean some intelligence from locals in their areas, many are hesitant to give up information for fear of retribution by insurgents.

Kunar Province remains one of the most dangerous regions in the country. One U.S. soldier was killed June 13 in Kunar, and two U.S. soldiers were killed three days later when the all-terrain vehicle they were driving hit a roadside bomb, according to Pentagon statements.