Comment by Cthulhu_

Plus deploying nukes would be a guaranteed escalation - after WW2 nobody has ever used nukes in war because of this.

But it would and always has been the last resort. If Russia feels like they have no choice left, they might do it.

But also, at the start of the war they used it as a deterrent, promising to use them if e.g. Ukraine were to strike across the border. That ended up being a false threat in the end, but you can see how Ukraine only slowly and carefully started becoming more and more bold with going across the border. All bets are off now though, with long range drones being used to target the very vulnerable refineries and oil industry. If they take out the power industry as well, and given time, it'll collapse Russia's military logistics network and isolate the front lines from supplies.