I'm pretty sure Russia started that by invading in 2014 and then 2022. Ending wars by giving invaders other sovereign countries doesn't work so well...it certainly didn't serve peace last time.
Ukraine is not what u think it is. It should've been divided along the Dnieper River into two different countries after the Soviet collapse. And yes Crimea belongs to Russia.
USA deliberately poked Russia to start this war. The goal of the USA is to whittle down the strength of the Russian military. Can't have a regional power in Europe.
Only the USA can have a Monroe Doctrine. Nobody else.