There actually have been recent disputes over this, as the WW2 Soviet army and the Soviet army crushing the 1956 Hungarian revolution with tanks (the origin of the word “tankie” BTW) were largely the same armies. Hungarian propaganda was blaming the Ukranians, but the army based on the deaths was proportional to the demographics of the Union, 30% UA, 60% RU, 10% mixed other IIRC.