Lots of nukes, strongest standing army in the world, strongly allied with the nations which have most of the other strongest standing armies, just for starters of course.
Dream on. There's like 12 of us (on the whole planet) who'd like liberty for all. Most everybody has some things they want to stop others from doing that has no impact upon anyone other than the originator of the action. Couple that with the ability to vote for people who'll spend money that belongs to other people on the voters and you've found a fine recipe for liberty-free living. The really nice thing is I can see it coming and will do reasonably well. And I will be laughing my @$$ off at all the losers in the streets. I won't care enough about all the scum who are bringing this around to piss on `em if they were on fire, unless they were upwind of my domicile. The future is not bright and most of us deserve that darkness.
Watch and see what happens to the Tea Party when real cutting is expected to take place. Walk into Burger King and most folks are ready to start a diet on Monday - but nobody does. Same thing with cutting government. Most everybody thinks cutting spending is fine. Most everybody has their own ideas on what should be cut and what needs more funding. There's no way to cut government. EDIT: No way short of an overthrow.
Here's hoping... If that were to happen the US would probably balkanize though... Not that I think that's a pejorative term like many do, I don't. Either way, I doubt "America" would have the same border which it previously did.
Oh, and btw, that "liberty for all" originally meant "all Americans". Not the whole world, including whatever 3rd worlder who could manage to scurry over the border. The founding fathers and first several generations were very keen on not getting wrapped up in foreign entanglements. Never were we meant to be the global police, or international critic of statecraft.