That mega-corporations now rule the world has been true for a while now. There is no reason for the US military to have a world-wide presence except to protect corporate interests. What we've been told is that corporate interests are US interests. That is clearly not true, but we've been told that so much it's become almost axiomatic. Big Oil, for instance, is a major reason for the US military to be active in many areas of the world, and Big Oil certainly does not have the welfare of the US as a priority.

All a country has to do to get the US sicced on them is to nationalize some resource. The US will try to overthrow the government, will try to assassinate the leaders, will stop at very little to get those resources back into private hands.

And no national politician can get elected in the US without mega-corporation money. The difference between Republicans and Democrats is largely a matter of words, not actions.