Framed in this way (assuming a population completely corrupted by propaganda) it becomes a matter of responsibility, not unlike what we already faced in germany.
I believe the proper course of action, in this instance and for posterity alike, is focusing and who is knowingly engaging in propaganda, and not who is being fed a false narrative.
It’s a broad answer and it leaves very little room for proportionate retaliation, but it’s the only approach, I believe, that foster progress and rightfully frame the issue of division and conflict in a tangible cause and effect dialectic.
If we now say, “Russian has let themselves be convinced to behave like monsters, therefore we must tread them as ones”, all future wars can and will be framed in this way. If we focus and the root causes, if we condemn manipulation of information, uneven education as among the greatest, most unacceptable, criminal act, I can see a world where at the very least, if you behave like a monster that’s out of your own “disposition”.