Don't forget, in the Starfist Universe the Marines are always going places to restore order or to protect the Confederation's interests.  Sometimes that's necessary, even in real life, but sometimes it leads to disaster and sometimes when on the surface invasions appear justified, once you look below that you find they weren't.  Those of you familiar with the series will know just which books I'm referring to.  We base these books on the fact that nothing changes in the world except technology. 

Now back to the 21st century, if we went places for oil or other resources we need that would make sense although it makes more sense to cut deals with bad people who have stuff we need.  But we went into the Balkans because we are the "good" guys, to bring "democracy" and "stop the genocide."  That was Bill Clinton's justification.  Anyone noticed that we're still there, even though they have nothing there that we need?  And if we went into Iraq for their oil, that failed because they haven't supplied a significant quantity of the stuff since we invaded.  Well, the justification there was, again, to bring "democracy" to the country.  Shit, Iraq's governed by tribal law, has been for centuries, and "democracy" there, or anywhere in the Arab world, is a fancy Greek word.  I thought at first, and so did Bill Clinton -- don't you Democrats take on airs -- that Saddam just had to go, but these days I'm convinced it'd have been far better if we'd just left him in power, seeing how things have turned out since we deposed him.  If we really want to conquer a foreign country we can do that with Coke, Hollywood's movies, McDonald's, and pop music -- America's youth culture trumps ideology every time.

My foreign policy is, deal with everyone but if anyone screws with you, kill 'em.