Fine, I'll play along. This is because American civilians are repulsed by the idea of causing harm to other people. In fact, they are so repulsed, that they see a video like this one (of soldiers using guns to kill people and break things) and they are repulsed and outraged.
American Soldiers have to be broken down and rebuilt so that they know that killing people and breaking things is what armies are meant to do. That is why we use our army to kill people and break things. The real problems come when we try to use our armies to do things like build things and be nice to people. That's not what it's for.
In fact, American Soldiers are so good at killing people and breaking things, that we get called in all over the world to save the people who think soldiers are like policemen with bigger guns.