As I understand it, the logic behind the claim of NATO's responsibility for the war in Ukraine goes as follows:
- When the Soviet Union fell, the West promised that NATO would not expand a single step eastward
- NATO broke that promise when it welcomed the Baltic countries and Poland
- NATO attempted in 2014 to extend further towards Russia by supporting a coup in Ukraine and preparing to include Ukraine in the alliance
I don't think the facts support this reasoning, but even before considering the validity of these points, it's worth noting that they, at best, justify an action of Russia against NATO, not Ukraine. This reasoning paints the picture of an hostage-taking crisis, where Ukraine is the hostage, Russia is the terrorist and NATO is being pressured to make concessions. Really, this picture is an indictment of Russia itself rather than NATO. Sympathy for Russia in this scenario is a case of Stockholm's Syndrome.
Getting back to the three points underlying NATO's supposed responsibility, the first point is an exaggeration of the discussions that took place around the reunification of Germany, as explained by Steven Pifer. As stated by Gorbatchev himself, no formal promise of non-extension was made.
The topic of ‘NATO expansion’ was not discussed at all, and it wasn’t brought up in those yearsWhat was discussed was the non-positioning of foreign troops in Eastern Germany.
NATO has conformed to this promise, to the point that a common complaint by NATO's eastern members was that NATO's presence was insufficient. See for instance this quote from 2017, three years after Russia's invasion started.
Poland has previously demanded a full-scale permanent Nato base on its territory, and officials admit that the promised reinforcement will only amount to a “speed-bump” for any potential invasion from the east.
The last point which describes the Revolution of Diginity as a coup by the CIA doesn't acknowledge Ukraine's ability decide for itself. It also blends the USA, NATO and the EU as a single uniform entity, which they are not, especially when it comes to relations with Russia. The leaked recordings of a discussion between Victoria Nuland give limited credence to the theory of US involvement. While I can imagine the CIA supporting the ousting of Yanukovich, it does not take anything away from the legitimacy of Ukrainians' yearning to leave Russia's sphere of influence and join the EU.
Before the invasion this year, Ukraine's access to NATO had been denied by Merkel's Germany in 2008 according to the BBC
She had opposed Nato membership for Ukraine in 2008, she said, because she had wanted to prevent escalation with Russia
Accession to NATO was not a valid justification for the urgent necessity of Russia's "special operation" against Ukraine.