Re: US should militarily intervene in South America
Kuwait/Iraq - it was not only that, after all. If Kuwait was invaded and nobody did anything, this would have created tensions between Iraq and its neighbors, which might have resulted in a "pre-emptive" strike from them. In the most oil-rich region on Earth.
Vietnam - there is the idea of trying to stop communist influence. And there is the burning of villages, with soldiers killed and wounded. The desire to do the first caused the second.
Korea, Vietnam, Cuban Missile crisis - all military conflicts during the Cold war. Was it these conflicts that you were talking about - or the Cold War itself? Once you accept the Cold war, you had to send military to these conflict zones. Now, the fact that every president presided over at least one conflict is kind of scary actually... but yeah.
And the USA did not send much military to Yugoslavia: except for some fighters, where a couple of them got shot down. During the conflict with Milochevic the air force did run out of bombs.
The US military is using up tremendous amounts of money - and dont forget the intelligence services too. But that is still within - uhhhh - maybe 5% of the GNP?