See i don’t even think that they could do that. Yes they have the biggest navy but if they get close to the shore within Russian missile range all of their carriers just turn into giant sitting ducks, extremely easy to sink with a few comparatively cheap Russian missiles. A carrier has no defense against a hypersonic missile, and losing one would be an utter disaster for the US, those things cost billions of dollars and take years to build. The only thing they’re good for in today’s age of advanced missiles is bullying small defenseless countries.

So yeah the US can project power around the world with its giant navy and bases all over the place, but in a war with a peer or near-peer power, even one without much of a navy like say Iran, anything within missile range becomes a liability.

A blockade would have to either be done by patrolling the oceans, far from the shore, or with submarines, but of course Russia has its own subs and could cause a lot of havoc to shipping in both the Atlantic and Pacific if it got to that sort of level.

Also, NATO is basically just the US, Turkey and France, everyone else is irrelevant and their armies are all but nonexistent, and i am not convinced Turkey wouldn’t just sit a NATO-Russia war out if they don’t think they have anything to gain from it and too much to lose. In which case as i said, i think Russia can win a defensive war on its own turf even without having to go nuclear, i don’t think they’re that scared of NATO especially as long as the US is overextended and has to maintain military presence all over the world.