Ever watch Full Metal Jacket? Here's one of the quotes:

Gunnery Sergeant Hartman: If you ladies leave my island, if you survive recruit training, you will be a weapon. You will be a minister of death praying for war. But until that day you are pukes. You are the lowest form of life on Earth. You are not even human, fucking beings. You are nothing but unorganized grabastic pieces of amphibian shit. Because I am hard you will not like me. But the more you hate me the more you will learn. I am hard but I am fair. There is no racial bigotry here. I do not look down on niggers, kikes, wops or greasers. Here you are all equally worthless. And my orders are to weed out all non-hackers who do not pack the gear to serve in my beloved Corps. Do you maggots understand that?

The service trains to kill. Harsh but true. Post war syndrom has been going on since the beginning of war.