No, I'm not so sure it does. Look at Roma, England (NOT the UK) and the Soviet Union.
All three were MASSIVE empires. The largest single polities during thier hay-day. Rome was a pathetic patchwork of government, which just happened to survivew because of it's military (for the most part). When the Roman Empire fell, the Romans themselves were doomed to be erradicated by being breed out, wiped out, or talked out, while the sun never set on the Brittish Empire (except for about 1.15 hours where they didn't have anything in the Atlantic... Hmm...) Thier fall was in no way mirroring the fall of Rome, which they obviously molded themselves off from in thier ruling style (just look at how many of thier 'colonies' rose up to shrug them off when the Brits decided it wasn't convenient to rule them) and they survived quite well once they were simply the 'Commonwealth.' The Soviet Union fell apart reletively bloodlessly (on a general scale. We all know that some blood was shed in a few places, but that was the people clearing house in thier own territories, NOT invading Russia) England would be incapable of raising the sheer man-power that it's military had even when the Empire was falling into it's current patchwork. The Soviet Union's former states are gaining in prosperity, albeit slowly in someplaces, and some of those nations fight side by side with US, as I see Polish soldiers every day. I can't help but feel pride in those men and women, as they are from the country where my real last name comes from... Such a grand thing, really, to see that people we once considered potential (and at times, real) enemies are now some of our best friends. Most of the time, I can't even imagine wanting to fight the Brits, and I see no reason whatsoever as to why I would ever want to fight the Polish...
Fighting the Russians, though... I still have NO problem with that. Best fight I ever had was a wrestling match with a former Soviet soldier. He won, but he couldn't walk for a good fifteen minutes after I was done with him.
As for war, I'd rather not. Too many good men on both sides. Our victory wouldn't be worth a war against them as things stand... Besides, that's what the Olympics are for.
Look at our empire.
http://en.wikipedia.org/wiki/U.S._empire
Look at the conflicts we have been in
http://en.wikipedia.org/wiki/Military_history_of_the_United_States
Look at Bush
http://en.wikipedia.org/wiki/Bush_Doctrine
Look at Truman
http://en.wikipedia.org/wiki/Truman_Doctrine
Look at the current war. Remember I support the U.S. Troops, not the wars, expect for the one in Afghanistain.
http://en.wikipedia.org/wiki/War_on_Terrorism
The. U.S. rules the world. You say we have no empire!?
I have more evidence if you want to see it.
Doctrines don't mean anything, because most of them are impossible to implement.
America ruling the world? PHAAGH! Tell that to the Russians, French, or, wait... who are those whom we call our best allies, the Brits? Yeah, tell the Commonwealth that we rule them. They'd laugh in your face. The French make fun of us, and the English, though no longer the Empire that IT was, still has more people then we do. In fact, it has nearly A THIRD of the TOTAL HUMAN POPULATION in it's ranks, while we have a measly 300,000,000. Think about that. 1.9/ .3 billion. Hmm... No, we don't rule the world at all. We barely rule OUR section of North America, so how can we be expected to rule the world? If we were truly an empire, we would have killed, crushed, or otherwise destroyed everyone who rebeled against us. We would have taken over England, France, Germany, Cuba, Northwest Africa, Panama, the Philipines, South-East Asia, South Korea, all of Italy, Mexico, Canada, and probably would have more client states then we have States in the Union. Oh, not to mention, there is no way that the people would consent to our having an Empire. Apart from Mexico and Cuba, all the NAMED countries I listed are our Allies, in one way or another.
Besides, as Neitzche said, all you have to do is know anything about a subject and you can feign being a master, provided you know how to draw people's oppinions out. Most of the time, you are fooling no-one but yourself after a while. Those who think that the UNITED STATES is an empire are fools. As Eric noted, we already gave up our Empire. Cuba, the Philipines. Can you imagine what Rome would do to it's 'allies' had they treated them the way, say, France and Germany treat us? They'd be invaded, enslaved, and even if they didn't actually conquer said nations, they'd exact tribute from those they didn't kill. And they WOULD kill.
Have we killed a massive number of people?
HELL YES, WE HAVE! And we're damned good at it too! The United States could go through and reduce every nation to rubble without having to resort to nukes, so long as the rest of the world doesn't either. It would bleed US white, but we'd be able to do it. Destroying a nation, defeating it, and conquering it are all different things.
Look at what we've done, though apart from our great success at warfare. We've built a nation where almost everyone can imigrate to (so long as it's legalally done) and built a life they'd never have had a chance to even DREAM about. When we razed Tripoli back in the early 1800's we started on the road to the World's police, even if all we were trying to do was protect our citizens from bring raided on the high seas. That's all we've really tryed to do. Make the world safe for our people. That is the right of every nation, and before you point at the Nazis and say that's what they were trying to do, need I remind you that what we did proved that we are not doing it just for ourselves, but for everyone? If we were out just for our selves, we'd have conquered Deutschland BOTH times we crushed them. Shit, durring our occupation of Germany after the Great War, we loved the Germans and were better loved by them then the FRENCH! Our own allies despised us, while our former enemies right next door saw us as liberators, Knights in Shining Armor, in some cases.
Let's face it, you are going against professional Soldiers, Skink. I might get pwned by David (Considering how, no matter what, once a Marine, ALWAYS a Marine) but the core facts remain that several of us have studied history for many more years then you, and in some cases most-likely, longer then you've been alive. I've mearly been studying it since I was about 8, and that was just 12 years ago. I don't know everything, but as our good Sergent Major will likely aprove of, if I don't know the answer, I know where to find it.
Danners, you start firing off FMs, TMs, and ARs, I swear i'll burn every copy of Starfist I own... (Then buy new ones without telling you.)