In the current context of Ukraine versus Russia the trick has been to tie everything to the invasion by Putin’s armed forces over four weeks ago, an undoubted act of aggression. Once you establish that as your launching point, preceding developments are rendered moot. Who cares about US promises not to expand the NATO---
If one were to ask the question “Which nation in the world commits the most war crimes?” the general international response might well be Israel or the United States---
In any event it is difficult to “convict” Russia as neither Israel nor the US has ever been held accountable for the war crimes they have committed, to include shooting and bombing civilians, hospitals, schools at random and occasionally wedding parties and other social gatherings.