One significant omission from this comparison: the Ukraine:Russia population ratio (~0.285) is almost TWENTY TIMES as large as the Taiwan:PRC ratio (~0.0163).

One significant omission from this comparison: the Ukraine:Russia population ratio (~0.285) is almost TWENTY TIMES as large as the Taiwan:PRC ratio (~0.0163). The Ukraine:Russia ratio is almost as large as the ratio between the Confederacy's non-slave population and the Union's population at the time the US Civil War broke out; and I suspect that some overly optimistic Russian military planners did not properly account for this. So, although it is harder for the PRC to invade Taiwan than it is for Russia to invade Ukraine for a number of reasons, I expect it to be more difficult for Russia to keep most of Ukraine pacified even if they do achieve their primary military objectives.