The relationship between NATO and USSR then Russia is complicated. The USSR requested NATO membership in the 50s as they were worried about Germany.
Everyone remembers Reagan saying to "tear down that wall" regarding the unification of East and West Germany, but do you remember Reagan also gave assurances to USSR that NATO would not expand as part of that agreement?
The USSR collapsed less than two years later, with Russia and a bunch of new countries remaining. Clinton broke the expansion promise, and NATO had massive expansion. And Russia did nothing in response.
There have been assurances that Ukraine, who sits strategicly on Russia's border, would not be allowed NATO membership, but the U.S. helped a regime change that was neutral on NATO/Russia (keep in mind Ukraine is made up of a lot of Russians and they did not want a war) to a pro-NATO stance.
These actions are at least partially responsible for Russia deciding to invade in 2014. You may recall Putin asked publically before the current war, for assurances Ukraine would not be allowed to join NATO, and he was not given them.
I am not a Putin fan, but I can understand why he would not want more NATO missiles on his border, just like we didnt want them in Cuba.
All of that said, I'd wish we'd stay out of these events, but we helped bake this cake.
I also find it funny that Europe is showing support by giving Zelensly a 1.9B loan yet criticizing the US for asking for reimbursement for what we have contributed.
Trump does some things well, some times we need an antagonizer on the foreign stage, and sometimes we need friendly diplomacy to get what is needed. Trump is great at the former but is abysmal at the latter.
Part of me wants to avoid a world war at all costs, including letting Ukraine handle it, but knowing we helped contribute to what is going on, I can't agree with Trump's current stance.