[blaser-waffle]

No nuclear powers are backing the Ukraine or Crimea. The US is explicitly backing Taiwan. When the CCP started conducting "exercises" near Taiwan during the Clinton era, the US sent 3 carriers to conduct "exercises" nearby.

And, as others have pointed out, they weren't trying to conquer all of Ukraine, just the parts with a "warm" water port, which also happened to have a lot of ethnic Russians. Limited scope, for a tactical gain (a seaport). The CCP, however, is trying to take all of Taiwan, and enforce their will on people who absolutely do not want it.

With a Nuclear India next door (and Nuclear Pakistan next to them), plus Japan, Vietnam, and a host of other countries that have a reason to be weary of China, it's a risky gambit. It is a good way to kickoff WWIII, for an island that is already, effectively, in the Chinese cultural and economic sphere.