askchapo

it's an important detail that Russia was not twiddling its thumbs while the far right took a grip of Ukraine, they used the opportunity to secure Crimea (Sevastopol is where the Black Sea Fleet is based) and immediately began arming the nascent separatists in Donbass, then not long after sending actual troops as well. These acts were in naked self-interest, Russia was never comfortable with the condominium in Sevastopol and the ongoing territorial dispute re: Donbass separatists was a low-cost way to theoretically disbar Ukraine from NATO membership in perpetuity^1^.

Attempts to stabilize that situation and keep Ukraine safely out of NATO for the foreseeable future with the ceasefires failed, and NATO/Ukraine kept sabre rattling making like they'd admit Ukraine to NATO with the ongoing territorial disputes anyway, leading to a much larger and frankly tardy full commitment of Russia's resources in 2022.

1: NATO's protocol to defend any members in a conflict is believed to foreclose the possibility for them to enter, as NATO would be drawn into a preexisting conflict.

I’m not sure if that was done by right-wing militias or official forces

the line between the two was/is very blurred as nazis were the first mobilized and most enthusiastic elements of the AFU in the Donbass. However, those nazis were most responsible for violating the Minsk ceasefire protocols, sometimes in violation of the orders from their government. there's a darkly funny clip of Zelenskyy personally yelling at them to obey the ceasefire (they did not)