The fact that Putin is lying to his people about this tells me two things.
1) he is afraid of what they'd do if they knew the truth
2) in rationalizing his actions, he sees a way out, or is trying to create one.
I'd be far more concerned about Nuclear War if Putin was out right telling his people "yeah, I'm commiting genocide, what're you gonna do about it?"
As long as he isn't cornered, and as long as the USA and NATO don't take his bait, we'll be fine.