is there anything anyone can do? sanctions wont hurt putin and now he has threatened the world with nuclear weapons? even if everyone cuts them off china wont.
It's too late to prevent the death and infrastructure damage already done, but not too late to unite in telling Putin he crossed a line that cannot stand. No one knows how resumption of diplomacy will turn out but I hardly think Europe is ready to see Ukraine reabsorbed into Russia. Ukraine is not Belarus, and even Belarus had a (suppressed) breakaway from its puppet regime last time around, which of course is part of why Putin's fury has spilled over into taking a crack at Ukraine and pointedly occupying Belarus to do so.
In fact, tough sanctions on people Putin has depended on
will hurt him. Existing sanctions had already deeply inconvenienced some of the people he has relied on. They were or are loyal only through his having allowed them to flourish for his cut of their greedy take.
How deep does purchased loyalty run? Putin's not sure. Part of the point of sanctions is to bring internal political pressure to bear on a leader who has invited imposition of severe sanctions by the international community.
So Putin reminds us that there are more cards in the deck and that he has some of them, even if there is no intent to use nukes and so to invite the glassing over of the planet. The problem of course that is a war in progress is not the same as a war game, and there's no flashing red light over the map of Ukraine right now saying hey if you do this it's game over for everyone.
There might be flashing red lights on threatened use of nuclear weapons in actuality, but a person in desperate straits can end up with tunnel vision, where every step taken seems to highlight the one and only logical option left. We don't know if Putin feels desperate yet or is still in megalomania land. He might end up somehow settling for having troops remaining parked in poor Belarus for quite awhile, having issued what he could come to regard as a severe enough lashing to Ukraine to hobble any overt Western lean on its part for the near term. The fate of the eastern provinces though seems unclear to me.
As for China: China still needs the purchasing power of its middle class already accustomed to buying western goods. So while China and Russia are currently best buds in the petro-based world of pipelines and mineral extraction, China of course has an eye out for where are the self-serving limits of supporting this guy Putin on his fool's errand of blatantly overriding a European nation's sovereignty. I would assume the Chinese are working behind scenes, possibly in consultation with one or another western nation, to suggest a quick reversion to diplomacy, even if they're willing to blink and wink at any Russian shenanigans or delay in the run-up to settling on a ceasefire.
But China's not averse to a roadmap on how far aggression against another nation by a large power can go these days. After all, at some point they do mean to bring Taiwan to heel, as shocking as that might still seem to some in the West. So it's useful to Xi to hang back a little and to see how things roll now in western reaction to Russian aggression in Ukraine.