The government is put into place by the Americans. They elect their own masters. Most of what the U.S. government does is the result of the demands and constant pressure stemming from the electorate. The aggressive foreign policy is a direct consequence of the semi-religious jingoism and fundamentalism that affects the majority of citizens.
I'm met both online and offline a ton of Americans with aggrandizing and myopic views. Like you I used to think they were victims of the state that time is past. They share the blame.