US law specifically precludes US arms or aid to the neo-Nazi paramilitaries. Trump also sent arms to Ukraine. There is no treaty with Russia that prevents the US from doing so (you can always prove me wrong by citing a source).
The US has not pushed Ukraine to join NATO. The Ukraine has had long planned to join NATO. NATO has not allowed Ukraine to join. Trump also armed Ukraine.
Biden was unwilling to guarantee that Ukraine would never join Nato. Why should the US make such an agreement?
NATO didn't stage a coup. The Ukrainian people rose up against a corrupt politician who had been paid $2 billion to stop Ukraine from moving closer to the EU.
Ukraine has long had a problem with corruption. The current president ran on an anti-corruption platform and was not a regular politician. Corruption is one reason Ukraine wasn't able to join NATO.
Tell that to the CIA, which is arming and training paramilitaries:. https://ca.news.yahoo.com/cia-trained-ukrainian-paramilitaries-may-take-central-role-if-russia-invades-185258008.html