The military doesn't have to condition people to kill. Not sure what that says about the human race but it really isn't necessary to condition people kill especially someone who is trying to kill them or would do given the chance. Irregulars are ineffective not because they are unwilling to kill but because they are unwilling to die. Military training conditions you to stand and fight when you natural instinct is to run.

Hell in bootcamp we typically shot at bulls eyes and not man shaped targets. They do some work to get you used to the idea that you might have to fight but these kids will have had a lot more conditioning to kill on their PS3 than they will ever get on the military.

I do think you are right that we dehumanize the enemy but the troops do that themselves, the military doesn't have to step in. When my son was in Iraq there were three kinds of people; them, enemies and potential enemies. Like all wars they had a nickname for the locals, hodgie, that helped separate them in the other class. The troops do things like that instinctively, they military doesn't have to bother with it.