This is mostly just public posturing and open diplomatic signaling.

Nuclear weapon submarines are always deployed, and have been since the advent of the Nuclear triad.

That's as true for America, as it is for China, Russia, UK, etc. Basically every county with both nuclear weapons and a capable submarine platform/program.

There's a saying: the dying serpent always bites. Empires usually die a slow death by overextending themselves in war.

I wouldn't be too worried in this case though, the economies of the US and the PRC are so intertwined, that US capitalists have more to lose than to gain by starting a hot war. The war hawks know they only have a few more years of military (specifically naval) superiority, which is why they make a lot of noise that it's now or never. But the PRC thankfully played the long game, and even accepted some trade deals that weren't in its favor, in order to tie their economies together, to prevent war.

The idea is a show of force to stop anyone from actually using them on anyone else and to get the other side to back down. No one, not even N Korea or Russia, really wants to use them. They aren’t that dumb yet fortunately.

Also, there are different tonnages of nukes. While every nuke creates an environmental disaster. Some are small enough to be localized with minimal fallout. Still not great, but not world ending either.

Brinkmanship

Maybe we reached "Cleansing" time...

Idiots in charge... Nukes on their hands... People doing wrong things over and over again and not learning the lessons...

you tell me...

If everyone would plant at least a tree 🌳and care about it and watch it grow and what does it take for the tree to grow, no one would talk with such ease about nukes and armagedon shit...

Do you really want to just let the big guys bully the small guys because there’s nothing you can do?

The threat to not move provides stability