...and it's a damn sight easier to **** up a carrier than a land base. The ideal is to have both, but if you insist on running a budget where you can't, then the carrier is the obvious one to do without.
As for overseas aid keeping people sweet - that's a bit dubious IMO (but only IMO) as when push comes to shove you can't rely on the people you bribed to stay honest.
(Amazingly enough).