When Bush invaded Iraq, I remember a scene when the US military showed an areal video of some Iraqi vehicle to reporters: the vehicle got hit, boom it goes, and everybody cheered. It wasn't even some kind of "We have to do this because this is war," it was pure joy at the destruction and death of someone they've never met.
And I guess it's unfair to pick on the US for that - that kind of trait is pretty much universal. All you have to do is to see the other side as less than human.