What motivation did the US have after WWI? To secretly siphon German Reichmarks into the US coffers? Are you implying that the US is the evil of the evil? Well watch out Hitler, we've done more Genocides than you then.
I don't know what propaganda you read but I know for a fact the US are good samaritans. Hell, we send aid to Cuba, our mortal enemy who almost started WWIII. Dude, just because we help people does not mean we're trying to inject our evil seed into them so they can do our every bidding.