KHOST, Afghanistan — Afghan and U.S. forces here are pressing hard to secure the country's volatile border with Pakistan ahead of the American pullout from the country next year.
Khost province, much like other areas in eastern Afghanistan, has been a traditional waypoint for foreign fighters, weapons and explosives moving from Pakistan into Afghanistan for much of the 12-year war.
The biggest of these so-called "rat lines" from western Pakistan, known as the Mansour corridor, runs through the volatile province.
Through that smuggling corridor, roughly seven to eight smaller insurgent supply lines run through Khost and points west, funneling weapons and fighters into provinces in central Afghanistan and eventually into the secure zone in and around the capital city of Kabul.
Many of the munitions, explosives and insurgent fighters used during a recent string of high-profile attacks inside the city likely came into the country through these rat lines.
"The rat lines [problem] is understood," Col. Val Keaveny, commander of the 4th Brigade Combat Team, 101st Airborne Division (Air Assault) told The Hill.
"We know the lines. The [Afghan National Security Forces] know the lines," he said in an interview at Forward Operating Base Salerno in Khost.
But with American and allied commanders handing off control of all security operations to the Afghan National Security Forces (ANSF), U.S. forces here are taking a different approach to protecting the border than the combat operations that have defined the fight here over the past dozen years.
U.S. units routinely conduct "street-level engagements" with the surrounding villages near the Salerno base and elsewhere in the province to gather intelligence on where fighters from the Taliban or the Pakistani-based Haqqani Network may be hiding out while en route to Kabul and central Afghanistan.
On one such mission, members of Whiskey Company, 2nd Battalion, 506th Infantry Division patrolled several villages with the Afghan police near the base, speaking with village elders and other community leaders.
During the operation, U.S. forces and ANSF members questioned local residents on any possible enemy activity in the area.
The point of those missions is to "already know the answers before we ask the questions," Lt. John Benton, platoon leader for Whiskey Company, told The Hill.
Benton's unit, and members of the Army's Human Intelligence collection teams who often ride along during these engagement patrols, want to know "the who, why, when, who [villagers] are married to" to set a baseline understanding for the area, the platoon leader said.
Knowing that baseline and seeing any changes to it helps U.S. and Afghan forces pick up on where insurgent forces may be hiding.
The flow of fighters and equipment from Pakistan has only increased as the American war in Afghanistan comes to a close.
Taliban and Haqqani commanders have been flooding the region with foreign fighters as the 2014 American withdrawal deadline nears.
"The madrassas are emptying" in Pakistan, in an attempt to drive more fighters into Afghanistan, Lt. Col. David Hamann, who leads the American Security Force Assistance Advisory Team at Combat Outpost Matun Hill, said in an interview with The Hill.
While the goal of those fighters is to launch attacks in Kabul and central Afghanistan, "they need to go somewhere to take a nap" while heading west, Benton said.
More often then not, many of the villages near the American base provide shelter and support to those fighters, he added.
But even after over a decade of war, U.S. and Afghan forces continue to face resistance from locals to provide information on possible enemy movements.
Taliban and Haqqani leaders have also adapted their strategies to evade Afghan and U.S. efforts to pick up on the network of safehouses and supply locations along the various rat lines running through Khost.
"They change their [strategies], we change ours," Benton said of the constant game of cat-and-mouse between U.S. and allied forces and insurgents along the border.
"But its been like that for the past 12 years," he said.