Speaking as a non-American who has travelled most of the world, I have little time for conspiracy theories.
Sure, the US (or any other nation and most individuals) would like to get its way by almost any means; I only question the ability. Most people are stupid - and that includes most people in government and banking - look at the mess they've just got us into. Like the rest of us, they just bodge along from day to day, never quite in control, never knowing quite what is going on. Conspiracies tend to unravel in farce - 'hey guys, let's make Castros beard fall out - that should stop world communism'.
It's cock-up rather than conspiracy in nearly all cases; conspiracies, like Watergate, tend to come trying to desperately hide a cock-up.