The movie Soldiers of Conscience brought to attention how student soldiers in the Army officer training programs at military host universities are trained to ‘kill reflexively’, without use of conscience and considering moral justification.
The best explanation of this training technique is probably best described in a paper presented to the Joint Services Conference on Professional Ethics in Washington, DC, January 27–28, 2000 by CPT Pete Kilner, instructor at the U.S. Military Academy. In a paper titled “Military Leaders’ Obligation to Justify Killing in War” he says:
Training which drills soldiers on how to kill without explaining to them why it is morally permissible for them to do so is harmful to them, yet that is the current norm. Modern combat training conditions soldiers to act reflexively to stimuli—such as fire commands, enemy contact, or the sudden appearance of a “target”—and this maximizes soldiers’ lethality, but it does so by bypassing their moral autonomy. Soldiers are conditioned to act without considering the moral repercussions of their actions; they are enabled to kill without making the conscious decision to do so. In and of itself, such training is appropriate and morally permissible. Battles are won by killing the enemy, so military leaders should strive to produce the most efficient killers. The problem, however, is that soldiers who kill reflexively in combat will likely one day reconsider their actions reflectively. If they are unable to justify to themselves the fact that they killed another human being, they will likely—and understandably—suffer enormous guilt. This guilt manifests itself as post-traumatic stress disorder (PTSD), and it has damaged the lives of thousands of men who performed their duty in combat.
For the rest of his paper see “Military Leaders’ Obligation to Justify Killing in War”