Crimea was done pretty cleanly in 2014. There might have been verbal denouncements, but there was no military response nor any chance of one. Most of the world unflinchingly just accepted that this presently and historically Russian-majority area eagerly agreed to be Russian.

I’m at least partially in agreement with WWario that it would have been better for Putin to also take at least Donetsk and Luhansk in 2014, to avoid the protracted mess that became of the region.