A "summer offensive" by Taleban militants is reportedly behind violent attacks perpetrated throughout Afghanistan in recent weeks. U.S. and Afghan forces say the insurgents are increasingly dependent on training camps and safe haven in neighboring Pakistan.
U.S. forces in Afghanistan's Paktika Province fire mortar rounds at a nearby mountaintop.
Insurgents have been using the isolated ridgeline to launch rockets into the U.S. camp in Orgun-E, not far from the Pakistan border.
These are America's frontline troops against the insurgency in Afghanistan. Their heavily fortified camp occupies a narrow strip of land separating the unstable border region from the rest of the relatively stable province.
First Lieutenant Sean Parnell says that in the past month, the attacks in this area have intensified.
"Just within the past four weeks, things have picked up so much it has been pretty much continuous operations. Every single man out here has been running hard," he said.
Lieutenant Colonel Chris Toner says most of the insurgents in this area make their base inside Pakistan, and only cross into Afghanistan for combat operations.
Pakistan originally rejected suggestions that Taleban and al-Qaida militant were using Pakistani territory to launch attacks into Afghanistan.
The Pakistanis now insist they are doing everything they can to help secure the border. The Pakistani military has deployed 80,000 troops to the region, and is increasingly coordinating its efforts with U.S.-led coalition forces inside Afghanistan.
Key to that coordinated strategy are forward bases like the U.S. camp in the town of Burmel, located closer to the border than Orgun-E, inside a dense network of dirt roads and narrow trails crisscrossing the porous border.
Soldiers based here use armed trucks to patrol the dusty countryside, avoiding roads that could be mined by insurgents.
In one of the small border villages, Captain James Dye orders house-to-house searches for any sign of militant activity.
"They do not stand out, that is the hardest thing with this enemy, they can blend in with the population, and without the population's help, pointing at a guy [and] saying, that guy does not live here, its very hard to distinguish them," he said.
He says the villagers here have been reluctant to help identify militants.
But that does not mean they are not here. A convoy passing through this village just last week was ambushed by at least a dozen suspected Taleban fighters. The U.S. forces say they escaped injury, and killed at least eight of the attackers.
On this visit, the village elders again insist there has been no sign of any insurgent activity.
He says he considers the Taleban outsiders, and promises they are not receiving any assistance from his community.
But just a few minutes later, a burst of gunfire sends the soldiers running for cover.
Insurgents on a nearby hilltop open fire on the soldiers down below before retreating into the surrounding countryside.
Within minutes, the troops are on the move, hoping to capture the militants before they slip back across the border. By early evening, though, it appears that the attackers have gotten away.
Colonel Toner says it is rare these days for U.S. forces to launch sweeping combat operations in the area. The goal now is twofold: limiting the conflict to the border, and making sure the rest of the impoverished province is safe for development.
"If I am fighting along the border, I am winning, because the population base is inside," he said. "Really what I am doing is, I am providing an opportunity for the government to get established, and for the people to get some sort of economic stability."
The U.S. forces in Afghanistan do not focus solely on military operations. They are paying local contractors millions of dollars for development projects including new schools, roads and water systems.
They are also helping train the new Afghan National Army, which has 30,000 troops and hopes to more than double in size in the next few years.
Almost all the U.S. bases in Paktika province include barracks for Afghan troops, and the two armies now work side by side on most operations.
But Colonel Toner admits it will be a long, slow fight.
He says most of the insurgents are Taleban, some al-Qaida, and he says there are also at least two local warlords with their own militia in the region staging attacks on coalition forces.
He says the insurgents themselves are from the surrounding area, a traditional Taleban stronghold, but there is mounting evidence that foreigners, including Arabs, Chechens, and Uzbeks, are helping train them inside Pakistan.
They typically attack at night, he says, and then slip back into Pakistan before sunrise. As long as they stay on the far side, the U.S. and Afghan troops cannot touch them.