Russia’s hypersonic missiles and new splice missile system can hit America. America’s missile defense system cannot stop these missiles from landing and in the case they are somehow able to, the splice system has accounted for that, they won’t be able to stop enough of them. Right now Russia has the capability of preemptively destroying the US outright without it having a chance to retaliate much if at all in response. I wouldn’t worry too much about a nuclear war, it would be more like a nuclear battle and then a very quick surrender by the rest of NATO.

The real question is what would that kind of detonation do to the environment? Modern nuclear weapons minimize fallout to maximize impact so there is a possibility Earth may not be screwed in this case, however this is a question for professional and non-hysterical scientists to answer. (So not the ones on Reddit)

some country in the anti-imperialist bloc (e.g. China) manages to prevent Amerika’s nuclear weapons from being fired and/or detonated; no clue if this is possible

Pretty sure that is impossible. China’s been working on some kinda algorithms for intercepting missiles, I think, but there’s just too many shit out there. Not to mentioned automated systems in other countries that would detect a launch and call for a retalitory strike.