Here's the thing, the people who keep saying that US bears responsibility for Ukraine's predicament are wrong. I'm Russian so I follow various sources (both Russian and Ukrainian) in the original languages. Putin has had his eyes on Ukraine at least since he came into power 20 years ago. In 2014 Igor Girkin (among others) was sent clandestinely to take over Crimea and start the war in the Donbas. Girkin is a monarchist and believes in "the Greater Russia". He believes that Russians and Ukrainians are the same people (an opinion Putin shares and has publicly proclaimed before the war).
The FSB has a whole department (the 5th service) devoted to subversion of Ukraine, including payment/bribes of billions of dollars to various gov't and media officials (one of whom, Viktor Medvedchuk, was captured by the SBU recently while attempting to flee house arrest).
Blaming this conflict on NATO and the US is part of Kremlin propaganda, including their "de-nazification" claims. If anything, this conflict has shown just how important NATO is in keeping people like Putin in check, as he would've gladly continued to the Baltic states and maybe others if his Ukrainian campaign succeeded (in fact, some Russian politicians have publicly stated this on national Russian TV recently).