I doubt Puerto Rico will become a state right now, because as a territory we get to tax them without representing them in congress. I'm unsure why they put up with that; maybe they just want protection. Say what you will about the rest of the world, but the U.S could likely curbstomp any other country on this side of the world, although maybe not a full alliance. I think Brazil is the strongest State (Capital S) in the hemisphere, although I've heard Canada is surprisingly badass for having a population measured on one hand.
Still, the only countries that would have the power to do some damage on their own are...
China (The second-biggest power in the world, could possibly be THE biggest but I think the economic manipulations they're doing would hurt them in a war)
Russia (?)(I'm not sure how well they stood up after the USSR fell. They're still a big player, I know that)
Germany (Proven time and again they're a national version of David, but without the victory record. They could hurt us, I doubt they'd win)
U.K (Would very, very quickly become a defensive war on their side but the U.K is made of friggin' water; no compression, no conquering)
Japan (If they geared up for war, they'd have an economic advantage over even the U.S, and they're tough little buggers too. I still think the U.S would win, but the casualty count on both sides would be huge.)
France (?)(If you count an unending resistance as continuation of a war, then France counts. Even we couldn't hold them down, even though we could nick their lunch money easy)
I can't think of any others, but I'm sure there are some out there. Any suggestions?
My suggestion is that someone might get offended that Americans think we could kick their ass, so maybe we shouldn't be discussing this. Much as I'd like to.
To be fair,
we probably could. Setting aside the question of whether or not the US population would eventually tire of unprovoked wars to a degree sufficient to incite forceful removal of our government (or if that is even possible), there is the issue that, while we
could beat any single nation (and likely an alliance including fewer than three of our major rivals), we would either come out ahead militarily but have an even more thoroughly destroyed economy (particularly if we went to war with China), or we would take nearly as much damage as our opponent. Unless we just keep knocking off little third-world nations with little or no real military force. If it remained a purely conventional conflict, the US could almost certainly defeat any other single nation (though
holding it would be another matter entirely), but would cause significant harm to itself in the process. In the event of mutual nuclear war, the US' material advantages would be essentially irrelevant, as most nuclear powers have large enough arsenals to destroy any other nation many times over.
So yeah, we
could, but it would essentially be national suicide unless we continue to go after our target of choice: the international equivalent of the parapalegic kid on the primary school playground. In that case, "Git yer jackboots ready fellas, wes got sum oppressin' ta do!"