What about this issue is particularly complex? Other than nuclear weapons? Russia has spent the last 20 years acting with total impunity, relying on a western reluctance to intervene. Russia is a world power if they are allowed to throw their weight around without consequence. The only reason not directly aid Ukraine in securing their borders is the threat of nuclear war. China is not going to got war with Russia against the US because of military intervention inside Ukraine's borders. That is an insane claim.
That seems like a good reason in its own right... Right? That said, they're suffering a lot of consequence at the moment so it's worth letting that pan out. The west drastically overestimated their capability, by that standard NK is a world power. I get it, I don't think your position there is wrong but...semantics.
>China is not going to [go to] war with Russia against the US
Never claimed that. The game for China is if they don't provide material aid, they get to maintain better relations with the west. I think the west broadly misunderstands their goals for international standing. They want to be recognized but if push comes to shove they'll just buddy up with Russia. Best to not provoke that. If the US decides to world police some more, along with three EU, that makes world policing the standard for world power and China will happily rise to that. They're very much watching what we do here.
China's government, like Russia's uses the west as a tool to consolidate power. The western world, and specifically NATO (which is really just another world for America in this context) serve as a looming enemy. We have now clearly seen that the actual actions of the West do not matter. China and Russia suffer from intense corruption, low overall standards of living, and the massive income and power gaps that arise from these types of governments. Western democracy ain't perfect, but there is a good chance that given the ability to accurately compare their options the Chinese and Russian populace would start to push back against the power structures. You can see this in the case of Hong Kong, and in Ukraine's westward trajectory.
Thus the people in power need to control information and unify the population in order to stay in power. If the west doesn't directly provide ammunition for this information war, they will just make it up. And they already do this. I have come to realize over the last 5 years or so that China and Russia have ZERO information in maintaining a truly friendly relationship with western (there needs to be a word for this that doesn't ignore Japan and Korea) democracies. They will continue to act in whatever fashion preserves the power structure, and that will include simply inventing threats. Such as Ukraines doomed bid to join NATO.
