Though the soldiers in the film did have a striking view on killing the enemy, it is certainly not their fault. Instead, it seems necessary to have this approach. While I will not pretend to understand how or why these veterans think what they think, it seems that it was essential to their own survival. In basic training, a soldier is broken down and built back up from scratch. The purpose is to erase your individuality and condition you to obey orders all the while ensuring your survival. Morality seems to often fall by the wayside in this process, giving way to a kill-or-be-killed complex. Perhaps the mind, in an effort to cope with such conditioning produces a state of denial in which the soldier derives pleasure from killing. Maybe this is why soldiers would often joke about horrifying aspects of war in trying to deal with it. Otherwise, from my own perception, one would break down into a form of shell-shock. My belief in these things is only strengthened by the fact that these men still seem to be stuck in the past. In the film’s interviews, the veterans recount the experiences in vivid detail and the emotions they felt then do not seem to have faded. War undoubtedly causes lasting psychological damage, but it seems that the preparation for war is the first instance of such damage. Soldiers are first trained to lose their humanity so that they can commit inhumane acts. Though this might be the best way to ensure their survival, it seems to also generate a never ending cycle that men cannot escape even decades after a war.
Though the Rwandan genocide is a bit different than trained soldiers killing, it seems the people had the same sort of kill-or-be-killed mentality. So, neighbors turning on neighbors is more of a result of a survival complex as well.