LANGLEY AIR FORCE BASE, Va. -- In the secretive U.S. war of armed drones, the kill chain runs through a highly classified, windowless brick building here.
In the darkened spaces inside, hundreds of young Air Force intelligence analysts work 12-hour shifts, carrying out a controversial strategy of long-distance remote attacks which are reported to have killed thousands of militants -- but are also believed to have killed or injured thousands of innocents.
President Obama's increasing reliance on armed drones to kill terrorist suspects has sparked an international outcry and a fierce domestic debate about the government's assertion of its right to kill in secret.
Virtually unnoticed are those who are riveted to computer monitors here for hours at a time, the fast-paced pressure they endure, the demand for perfection and the constant risk of error in this new form of warfare: digitally-enabled high-altitude strikes managed from thousands of miles away.
Theirs are the unseen faces of Obama's drone war, a generation of Americans who are every bit engaged in combat even if they are not ducking incoming rounds and their fatigues are not soaked in the sweat and dust and blood of Afghanistan.
The human stress, senior commanders here acknowledge, is "extremely high."
When a U.S. special operations forces team is poised to raid a suspected insurgent compound, when a Marine squad in Afghanistan is alerted to an ambush, when a gathering of men identified as terrorists disappears in the bloom of an explosion in Pakistan, these analysts likely played a key role.
And with the White House driving an exploding demand for more flights by reconnaissance and attack drones, an increasing burden is falling heavily on the enlisted Air Force men and women here -- "airmen," in official terminology -- often just a few years out of high school.
The stress is already so high that concerned commanders have assigned a psychologist and a chaplain with top security clearances to work full time inside the facility.
The drone war is in full swing. U.S. armed drone strikes are reported to have killed more than 2,500 Taliban, al Qaeda and other extremist leaders in Pakistan alone. But in Pakistan, Yemen and Somalia, drones strikes have killed an estimated 900 civilians and injured more than 1,200 civilians since 2002.
In Afghanistan, the military struck at targets 494 times last year with armed drones, according to data that has since been removed from the Air Forces Central Command website. Information on the number of Afghan civilians killed in these strikes is anecdotal, but powerful.
These attacks are often portrayed as a highly technical, robotic form of warfare. But behind every strike are hours, days and even weeks of surveillance and analysis by the airmen who work inside this Air Force Distributed Common Ground Station. It is the largest of five globally networked facilities that receive and analyze the data flowing back from drones and manned spy planes like the venerable U-2, and then package the intelligence for operations.
Senior Air Force officers acknowledge that in this vast, darkened room where hundreds of analysts struggle to keep up with the deluge of data, the potential for error -- the possibility of taking innocent life -- is ever-present, just as it is in ground combat operations.
"Burn-out is obviously a big concern for us," said Air Force Col. Mike Shortsleeve, a veteran intelligence officer who commands the 497th Intelligence, Surveillance and Reconnaissance Group that mans and operates the center here.
Air Force researchers and others who have studied the airmen here know that the stress and tension that build during weeks and months of staring at monitors can lead to loss of concentration. What is not clear is whether fatigue plays a role in the tragic errors that occur in wartime, as happened in the NATO air strike in Aghanistan earlier this month that reportedly killed 11 children.
"Ultimately you do find incidents like that, and they are tragic and something that, obviously, we take very, very seriously, and we go back and find out why it occurred," said Shortsleeve, whose name is a translation of the French, courtemanche.
"That particular incident we didn't work, and I don't know what it entailed. It could be people never left the (targeted) facility and we didn't know they were in there. It could be a miscommunication, the guy on the ground thinking he had the right place," he said.
"Unfortunately these incidents happen, but I would say the effort that is put in to try to prevent them is enormous," he continued. "Any time we are working stuff on the ground, constantly in the back of our minds is, what is the possible collateral damage, what happens if the mission goes down, a missile hits it ... we are constantly working to prevent this, but inevitably you are not going to prevent everything."
The airmen here do labor under an immense workload.
For hours at a stretch, they search through an avalanche of video, still photos, communications intercepts and other data in an intense manhunt to identify, track and target insurgents or terrorists to be captured or killed. Digital chat rooms, email and phones connect them with drone pilots, special forces commandos, battalion operations centers and others to nail down "actionable intelligence."
Often, they'll stare at a suspicious compound for days, logging every detail of daily life, tracking women to the market and kids to school, determining by watching their behavior whether visitors are locals or outsiders. The presence of women or children puts the target off-limits.
When a target is identified and the absence of non-combatants verified, a word will flash from the pilot of a circling armed drone -- "Rifle!" -- indicating that a Hellfire missile or other munition is streaking toward the target. Analysts here will watch to make sure no children wander into the target area -- the laser-homing Hellfire missile often fired from drones can be diverted at the last second if needed, Air Force officials said.
After a strike, drones swoop in for a close look so analysts here can assess the damage.
This facility is not involved in the drone strikes managed by the CIA, which include three attacks during the past week in Yemen, said to have been aimed at senior members of al Qaeda in the Arabian Peninsula (AQAP). The CIA and the Defense Department manage separate armed drone operations, a division which the Obama administration is seeking to end by bringing all drone operations under the Pentagon. Officials said the transition of the armed drone programs is not yet underway.
Eventually, though, the task of conducting the drone war will fall entirely on airmen like these, who represent a new phase of warfare. For centuries, man has struggled to find ways to kill the enemy without exposing himself to harm. This is a partial success: Here, they can kill without being exposed to physical harm. But the killing can impose a cost nonetheless.
Much of the stress "comes from the helplessness they can feel," said Air Force Maj. Shauna Sperry, the psychologist who has worked inside this facility since November. "They are so young," Sperry told The Huffington Post. "They do what they have to do, but there is a toll that is taken."
Asked about "moral injury," the violation of one's moral principles, she said: "That's a pretty accurate description of what some of the individuals here experience. Things are happening, they see it happening and there's nothing they can do to change it."
The amount of data that pours into the five intelligence centers every hour is overwhelming. Since 9/11, the "take," just from drones, has skyrocketed by 6,811 percent, according to the Air Force. Every day, drones transmit back 1,600 hours of full-motion video -- the equivalent, officers here like to say, of two entire seasons of NFL football. Every day.
This one facility's servers handle 125 terabytes of data per day (one terabyte is 1,000 gigabytes, or 1 trillion bytes).
The data stream is still growing, thanks in part to new data-gathering technology such as Gorgon Stare, a drone-mounted sensor with nine cameras that can scan an entire city at once. And the number of drone combat air patrols (CAPs), defined as having one drone aloft on a mission 24/7, is currently at 61 and is scheduled to increase to 65 later this year.
To try to meet the dramatic expansion of the workload, the number of personnel assigned here to process and analyze data has more than doubled in the past two years, from 350 to about 800. Already, this facility, built only three years ago, is bursting at the seams. There are not enough desks for everyone.
During a 12-hour shift, analysts stare at their screens an average of eight hours, with four hours off for meals and administrative work, according to data provided by the Air Force. But the high pace of operations often requires more: last month some airmen spent as much as 11 hours of their 12-hour shift at their stations.
"We are classified as a weapon system, and the work goes on 24/7 and they are involved in the kill chain -- they are helping make the calls of what we're seeing down there," Shortsleeve told The Huffington Post. "In the event something has to be struck, the airman out there will be making some of these calls in conjunction with the crew flying the platform, to make sure we are going after what we need to."
"When you do this every day, day in and day out, to be mentally in the fight every single day, that does eventually take a toll on you," he said. "There are definitely moments of sheer -- you're on fire, the stress level is extremely high, especially when they're going to take somebody down or a strike is going to occur."
There are also long hours when airmen are starting at a screenful of Nothing Much Happening. But there is always the fear of missing something critical.
Officers and airmen who have served in Afghanistan or Iraq say this work resembles the mix of boredom, loneliness and stress of being deployed on a combat tour -- but not being able to come home and relax when the deployment is over. Some of these airmen work the night shift here, 7 a.m. to 7 p.m., for four or five years before being transferred to another facility of the same kind, to again work the night shift.
"It's pretty fast-paced sometimes," said Samuel, a 25-year-old Air Force staff sergeant who gave only his first name for reasons of personal security. He said he works between 36 and 46 hours a week, with a mandatory 10 hours of rest between shifts.
That rest period may not be enough. According to a 2012 study of this facility by the policy think tank RAND, over 40 percent of the intelligence personnel said shift scheduling and long hours were a top source of stress affecting job performance. The RAND study said such high levels of stress can include of exhaustion and cynicism, and low levels of concentration.
"Even as intelligence analysts are expected to remain alert and focused at all times, they are faced with conditions that would directly affect their ability to sustain this vigilance," the study concluded, adding: "The leadership likely has good reason to be concerned both for subordinate airmen and their ISR (intelligence, surveillance, reconnaissance) mission."
That report, and another commissioned by the Air Force, helped the command here win positions for the full-time chaplain and the psychologist, Maj. Sperry. Each holds 30 to 40 formal counseling sessions a month, and they often walk the halls, stopping to chat with airmen informally.
In all her counseling sessions, Sperry said the goal is "to return them to their pre-morbid -- normal -- condition. They come, they get some quick interventions, we get them back on track."
Surprisingly, the Air Force has not made much progress in automating the work of scanning video and other data to ease the human workload.
The Pentagon is working feverishly to develop software that can scan the flood of data and alert analysts to unusual activity, much the way the National Security Agency scans data streams for pre-programmed words or phrases in English and other languages.
Nothing like that exists for the airmen here. Air Force officers acknowledge they have much to learn from Google.
"There are some things we do with software that can help us, but in reality, it's in the infancy stage," said Shortsleeve. "It's something the Air Force is really pushing hard on, because we realize we can never sustain [the growing workload]."
But machines will never replace the analysts. What they do "inherently is a human endeavor," Shortsleeve said. When it comes to judgments about whether to strike or not, for instance, "It's going to require something between the ears to make that call."
Even so, Defense Secretary Chuck Hagel recently rejected a proposal to award drone operators with a combat medal. The idea had come from Defense Secretary Leon Panetta as he prepared to retire in February.
"I've seen first-hand how modern tools, like remotely piloted platforms and cyber systems, have changed the way wars are fought," Panetta said at the time. He said the work done by those who operate these systems "does contribute to the success of combat operations, particularly when they remove the enemy from the field of battle, even if those actions are physically removed from the fight."
But the proposal drew such an embittered outcry from military traditionalists that cancelling it was one of the first actions Hagel took after he was sworn in at the Pentagon Feb. 27.
In a memo to the Gen. Martin Dempsey, chairman of the Joint Chiefs of Staff and to his personnel chief, Hagel said combat medals should be reserved for those "who incur the physical risk and hardship of combat."
Maybe so, but the risks and hardships are real -- as is a war with a new kind of battlefield, a war with no end in sight.