Is America fighting for its empire?

Today my Archaeology teacher was talking about how every empire eventually completely caves in upon itself in one form or another, and I began to entertain the possibility that through all the protesting, arguing, and disagreement- perhaps the United States is acting accordingly.

If you consider what it will be like reading about the US 200 years from now, will its fall be that big of a surprise? The writing has been all over the wall since the 50s, and has riddled major media since the 80s.

So; is America justified in its actions to defend the empire, even if they don't come to truthful terms with them (has anyone ever?)

The great thing that came out of WWII, and eventually, as a residual effect, the Cold War, was that Europe finally, more or less, learned its lesson.  It contributed to the collapse of the British Empire, and it's why they've contented themselves with being smelly, Godless pussies, and God bless them for it. 

The infuriating thing about America is that at the rate we're going, it's going to TAKE us being the bad guys in something even bigger for us to get our comeuppance.  The reason why this is especially frustrating is because we have history's lessons right before us.  I think that our national consciousness is roughly in the same place that Europe's was a century ago-superiority validated by affluence, on uneasy terms with the rest of the world.  Trigger happy.

That last bit was conventionally liberal, yes, but get it straight-I love America.  McDonald's hamburgers are motherfucking delicious.  BECAUSE I love America so much, I am interested in whatever intellectual or social action will save it-from the external, or from itself, if need be.  If America could chill out and still exist in another 500 years, and never actually GET its comeuppance by paying close attention to the lessons of history, I'd be pleased.  But that probably won't be happening.