Well, it is a bit more nuanced. In 1990s there was a surge in various nationalist movements in ex-USSR republics trying to establish national identity on ethnic grounds. In some countries this resulted in armed conflicts with ethnic cleansings. In others minorities were discriminated or pushed to severe their historical and cultural ties. “Alien” passports in Latvia and restrictions on teaching of Russian language in Ukraine were the most notable examples. Russia traditionally protected Russian minorities in Baltics and Ukraine, which resulted in tensions between the countries. Indeed, when you build an ethnic national state and ignore large minority with ties to a nuclear superpower, you may be worried about survival. Whether ethnic national state should be a thing in XXI century is another question (maybe we should also ask Belgians about how do they feel about speaking French).
I am a firm believer in hat it was NEVER about protecting russians abroad. I'm from Latvia and might be biased, but evidence points that they have other reasons behind their continuous aggression.
