China and Russia fully settled their territorial claims in 2003.

The ressentiment is mostly from Chinese ultranationalists that have been censored by the government.

> The ressentiment is mostly from Chinese ultranationalists that have been censored by the government.

That is good to know, thank you! I'd like to say though that until recently annexing Crimea not to say bombing Kyiv was something only ultranationalists in Russia would call for. And as far as I can see from the outside, official rhetoric in China is getting more heated and nationalist, pretty much like it was in Russia.

this is correct. Too many 'china watchers' look at the Qing era maps and think PRC want to return to those borders. Vast majority of territorial claims have been settled by the PRC, almost always conceding loss of territory.

they should use a casus beli while russians are distracted

I don't think they will. Russia is being isolated from the Western world and will naturally become very dependent on China. They will get what they want peacefully sooner or later.