I remember a genre that is mostly just make believe but bear with me a bit. I can see now that it would really be possible to take one of Latin America's country's by a coup de main with say 100 trained and armed guys and in this case, let us posit former SEALS. You could see them entering the Presidential palace, killing everybody there and then announcing that their man is the new ruler of Venezuela.
Would it work? Sure it would.
Would Venezuela go up in flames as they fought for their whatever? Perhaps but I really don't see how this would be any different from what is going on there now. In short, you settle in, rub out the obnoxious ones and there you are, running a whole country like Venezuela.
I think in the 70's an author could get away with such a scenario but here in the early days of WWIV I don't think they'll go for that. Laziest people I know are former SEALS and in my own experience getting them to do anything worthwhile was an epic feat.
And, at the end of the day, you'd like own Venezuela. Nobody wants that.