Every day, thousands of Afghan men and hundreds of trucks and cars stop at the gates of this sprawling base in northeastern Afghanistan.
Each man and vehicle then goes through a series of searches before entering the compound, where 20,000 U.S. service members are stationed.
The job of making sure Bagram's defenses aren't breached - and those service members' lives aren't endangered - falls to Lt. Col. James Lowe of Shaw Air Force Base, commander of the 455th Expeditionary Security Forces Squadron.
Several hundred airmen make up Lowe's security squadron, the largest of its kind in Afghanistan.
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Airmen man the base's watch towers, patrol its 11 1/2-mile perimeter road and keep an eye out for anyone trying to sneak in with a gun or a bomb strapped to his chest.
Keeping the base secure is the top priority of Brig. Gen. Steve Kwast, the top Air Force commander at Bagram. Unless the base is secure, its mission - including handling the C-17 and C5 transport aircraft that regularly whistle in from South Carolina's Charleston Air Force Base - can be jeopardized, he said.
Bagram's defenders have found "several incidences of people having bomb-making materials, drugs and other illegal items," according to an Air Force report.
But, so far, armed insurgents or suicide bombers have not slipped past the "cops," as airmen refer to the security forces.
"The results speak for themselves," said Lowe, deputy director of force protection for 9th Air Force headquarters, based at Shaw.
While Bagram is among the most fortified bases in Afghanistan, there are some things the cops can't stop.
Among them are rocket and mortar attacks launched from the surrounding countryside.
Three U.S. service members have been killed in "indirect fire" incidents at Bagram so far this year, the most recent on Sept. 19. Indirect fire means attackers launched their weapon without seeing the target.
When then-Vice President Dick Cheney visited the base in 2007, a suicide bomber attacked the base. But the bomber never got past the base's first gate, nearly a mile from where Cheney was visiting troops.
Base defense is a specialized job in the Air Force. Security airmen are trained in just about everything from light infantry tactics to how to slap the cuffs on miscreants.
Having airmen guard an air base makes sense, Lowe said. "We have a dedicated, single unit to do the defense of a base."
The airmen, though, don't do the job alone, Lowe said, citing the "cooperative efforts" of other units on base.
One of the toughest jobs the cops have is making sure those who enter the gate are not armed.
Employees of a security contractor pat down local civilians while security forces personnel, assisted by electronic gear, supervise the searches.
Because the searches are so extensive, it can take up to an hour for someone to work his way through the checkpoints and onto the base. Those who are impatient and try to cut into line are sent home.
Bagram's defenders face some unique challenges because some 4,000 Afghans live in several villages surrounding the airfield, including one that is within a few yards of a watchtower.
From their outpost, Senior Airmen Juan Solis and Timothy Lewis track the flow of cars, bicycles and donkey carts into the village of Famya-oeat.
The village is a former Soviet army barracks complex abandoned when the mujahideen captured the base in 1989. Separate, two-story, white-painted, concrete block schools for boys and girls are on the village's outskirts.
"We just keep an eye on the village in case we see anything suspicious," said Solis, who is from Salinas, Calif.
Another challenge the security airmen face is navigating the barren fields surrounding the base that have not been cleared of Soviet-placed mines, Lowe said.
"I worry about the mines," said Lowe, a native of Caldwell, Kan. "I'd rather not have mined areas within my perimeter, but that's all part of the legacy of the Soviet Union."
Lowe, who is here for a yearlong tour, said he is proud of the work his people are doing in a "strange land" far from home.
"Is it hard duty? Yeah," Lowe said. "But they come here prepared."