I think that the United States like to spread power until they'll have none. The Soviet Union did the same thing. The thirty two republics that now stand, what do you think they were fifty years ago? Nothing. The Russian federation built absolutely everything for what is now east of berlin. That's the reason The Soviet Union fell apart. They helped everyone. Hell, if they were concerned into building towards Communism than at the moment the United States would have been far below Europe.

Not to start a rant here, but America, China, the entire world shivered at the word 'Communism' because communism is a utopian government that states ultimate power to yourself. Communism is devised as everything being free. Healthcare, schooling, colleges, everything. Communism pays the people by need, not by ability. Imagine you're doing the same thing over and over again. Takes nothing. Yet if you need food, shelter, etc. the government provides it if proven that you have no $$$. It's a foundation build on trust as well.
Back to what you said about global police. If you think they went to the Middle East to 'stop terrorism', than that's pure bologna. George W. Bush, after the Congress approved, sent troops to iran, iraq, and other sh*tty countries as a placebo affect after 9/11/1, while guess whose oil company was drilling away in the Middle East? The Presidents. Never a good reason to send money to third world countries , Troops to other countries. Why let your own people die, worsen your own economy, and stretch yourself thin. It's a complete waste of time, money, and lives.