You don't count Russia as a peer country? They have the ability to completely destroy the United States 45 minutes after Putin makes a phone call. If nukes are too theoretical for you, consider this: They can occupy several NATO members, overnight, and present us with a fait accompli. Then we get to choose between a protracted war, with a nuclear armed state, or the abandonment of those allies and collapse of the post-1945 world order. NATO would probably win a protracted war with Russia -- assuming it didn't go nuclear, a very big assumption -- since economics, technology, and demographics are on our side, but it would be very costly in terms of blood and treasure.
China is definitely a near-peer country. They already have the ability -- without using nukes -- to make it extremely costly for us to honor our commitments to our Asian allies. They can rain conventional missiles down on American soil -- Guam and the NMI -- and if a conflict went nuclear they could exact a very heavy price from CONUS. The rest of the near-peers are all allies (Germany, UK, France, Japan, Israel) or at least friendly competitors (India), so we've got that going for us at least.
(Actually, I'm glad that we dominate -- I just think it's a bit overkill to do so by so wide a margin.)
Well, that's an interesting observation. You kind of surprised me with that one. Why is it "overkill?" You specifically cited the USN to prove your point but I think you're ignoring the reality that the USN has obligations in every ocean and sea on the blue marble. 10 supercarriers sounds like overkill, but in reality you can only deploy about 1/3 of them at any given time; the rest will be in the yard for maintenance and overhaul. Four of them are deployed right now, which may be four more than anyone else has, but it's still pretty thin coverage when you think about the demands placed on the USN.
Don't get me wrong, I do see a lot of waste with our defense spending. I'm not certain why we still maintain a force of ICBMs when SSBNs are infinitely more survivable. I don't understand why cheap and proven platforms like the A-10 fall out of favor. There's a lot of things I would do differently if I was SecDef. Alas, he hasn't asked me for my opinion. :)