Humans without respect for humanity. These are not innocent civilians were talking about killing. They are real bad guys who would like nothing better than to kill an American. They dont wear uniforms so they can blend in with innocent civilians and use them as cover. They have no respect for human rights and would murder children to acheive their objectives. Taking some joy for ridding the Earth of those scumbags, I see nothing wrong with that.

I don't thinks it the question of "How does a society successfully absorb back into the fold persons who are "psyched about the prospect of killing", but rather how does the soldier blend back into a civilized civilian life.