I think what Putin fears the most was that euromaidan could spread to Moscow. A slavic orthodox country on his doorstep making moves to become a Western style l

I think what Putin fears the most was that euromaidan could spread to Moscow. A slavic orthodox country on his doorstep making moves to become a Western style liberal democracy was a threat to the idea of Russia as the centerpiece of the Russian language/culture/religion empire, all headed by a tsar with absolute power. NATO? For all the propaganda about evil NATO about to attack Russia, the troops that Russia normally has stationed against NATO and Finnish borders are now all in Ukraine getting their asses kicked. The NATO and Finland borders are empty. Ergo, in reality Putin is not (correctly so) afraid of any NATO attack.