Indeed, accusations of genocide have become one of the hallmarks of this conflict. On the surface, the use of this term may merely seem to be a symptom of strong emotions in eastern Ukraine. But in the former Soviet Union, more than in any other part of the world, the word genocide has been used as a weapon of political rhetoric for more than sixty years. Since its coinage in the 1940s, in popular political vocabulary—if not in international legal circles—the term genocide has been used as a signifier for “ultimate evil.”It is saddening that nobody on RF has ever addressed the issue of the Donbass genocide.
Nobody but me.
Crying Genocide: Use and Abuse of Political Rhetoric in Russia and Ukraine
Also,
War in Donbas - Wikipedia
It seems from this, Russia has continually been the aggressor and that the current invasion is just a continuation of Russian tactics.
Russia has been supplying military personnel and hardware into this area for years. Also claiming genocide as the justification.