The USA barely has any involvement here. Or maybe it does in the background, I dunno.
But Ukraine is very very proud to not be Russia. They have Kiev – Kiev is claimed as the 1000 year old ancestor of three nations.
Russia feels that Ukraine has a separate identity ONLY due to what amounts to a clerical error and what they consider a broken promise from about 400-500 years ago.
Their histories are far longer and their collective memories different.