In the early 1970s, some psychiatrists listened to soldiers talk about such incidents at “rap groups” organized by Vietnam Veterans Against the War. Until this point, soldiers bearing psychic wounds tended to be dismissed by the military as cowards and malingerers. (“Your nerves, hell — you are just a goddamned coward,” Gen. George S. Patton snapped at a soldier in a hospital during World War II.) The Yale psychiatrist Robert Jay Lifton, who sat in on the V.V.A.W. rap groups and wrote about the disfiguring effects of killing and participating in atrocities in his 1973 book, “Home From the War,” helped to recast these veterans as sympathetic figures. Lifton argued that these former soldiers were burdened not by cowardice but by the guilt and rage they felt about their involvement in a misbegotten war. In his view, moral and political questions were inseparable from Vietnam veterans’ psychic wounds, to the point that he believed activism to end the war could lessen their guilt and foster healing.

When PTSD was officially recognized in the Diagnostic and Statistical Manual of Mental Disorders, in 1980, many hoped it would lead society to reckon more honestly with the ethical chaos of war. The first definition included not only survivor’s guilt but also guilt “about behavior required for survival” among the potential symptoms, language that addresses acts soldiers perpetrated that went against their own moral codes. Over time, however, the moral questions that animated reformers like Lifton were reduced to “asterisks in the clinician’s handbook,” notes the veteran David Morris in his book, “The Evil Hours,” as military psychologists shifted attention to brain injuries caused by mortar attacks and roadside bombs. One reason for this may be that focusing on such injuries, and on harmful acts in which veterans were the victims, was more comfortable for the military. Another is that it may be more comfortable for V.A. clinicians, who weren’t trained to address veterans’ moral pain and who “may unknowingly provide nonverbal messages that various acts of omission or commission in war are too threatening or abhorrent to hear,” noted the authors of the 2009 article on moral injury in Clinical Psychology Review. Avoiding such conversations was untenable with service members returning from Iraq and Afghanistan, who were enmeshed in messy counterinsurgency campaigns that often involved close-range killing and noncombatants. According to Brett Litz, a clinical psychologist at Boston University and an author of the 2009 article, “35 percent of the traumatic events that led soldiers to seek treatment for PTSD in a recent study were morally injurious events.”

When the drone program was created, it seemed to promise to spare soldiers from the intensity (and the danger) of close-range combat. But fighting at a remove can be unsettling in other ways. In conventional wars, soldiers fire at an enemy who has the capacity to fire back at them. They kill by putting their own lives at risk. What happens when the risks are entirely one-sided? Lawrence Wilkerson, a retired Army colonel and former chief of staff to Colin Powell, fears that remote warfare erodes “the warrior ethic,” which holds that combatants must assume some measure of reciprocal risk. “If you give the warrior, on one side or the other, complete immunity, and let him go on killing, he’s a murderer,” he said. “Because you’re killing people not only that you’re not necessarily sure are trying to kill you — you’re killing them with absolute impunity.”

Langley Air Force Base in Virginia is home to part of the 480th Intelligence, Surveillance and Reconnaissance Wing, a unit of 6,000 “deployed in place” cyberwarriors. They work on what is known as the “ops floor,” a dimly lit room equipped with computers streaming footage from drones circling over numerous battlefields. Many of the enlistees arrayed around the screens are in their 20s and might pass for stock traders or Google employees were it not for their military boots and combat fatigues. But the decisions they make have far weightier consequences. According to a recent study by a team of embedded Air Force researchers who surveyed personnel at three different bases, nearly one in five I.S.R. analysts said they “felt directly responsible for the death of an enemy combatant” on more than 10 occasions. One analyst told the researchers, “Some of us have seen, read, listened to extremely graphic events hundreds and thousands of times.”

“Over all, I.S.R. personnel reported pride in their mission, particularly supporting successful protection of U.S. and coalition forces,” the survey found. But many also struggled with symptoms of distress — emotional numbness, difficulty relating to family and friends, trouble sleeping and “intrusive memories of mission-related events,” including “images that can’t be unseen.”

As at Creech, steps have been taken to try to mitigate the stress: shorter shifts, softer lighting, embedded chaplains and psychologists. Counteracting this is the workload, which has escalated as drones have assumed an increasingly central role in the battle against ISIS and other foes. According to Lt. Col. Cameron Thurman, who was then the unit’s surgeon general, the number of acknowledged missile strikes ordered by Central Command in the United States rose substantially between 2013 and mid-2017, even as the size of the work force has remained unchanged. “You’ve got the same number of airmen doing the same number of mission hours but with a 1,000-percent increase in those life-and-death decisions, so of course their job is going to get significantly more difficult,” he said. “You’re going to have more moral overload.”

A bald man with a blunt manner, Thurman sat across from me in a windowless conference room whose walls were adorned with posters of squadrons engaged in remote combat operations. Also in the room was Alan Ogle, a psychologist who was an author of the recent survey of the 480th Wing. On the PTSD scale, Ogle said, members of the unit “didn’t score high,” owing to the fact that few had been exposed to roadside bombs and other so-called life-threat events. What seemed to plague them more, he told me, were some forms of “moral injury.”