I stand by this. We haven't gone 75 years without a nuke incident only for it to happen now over Ukraine. If NATO tries to invade Russia, then yes a nuke gets in the air.
If NATO keeps Russia from a wholesale slaughter of the Ukrainian ppl, there will be a LOT of sabre rattling but I dont think a nuke gets off.
We came really close to dropping nukes three times (Korea, Vietnam, Cuba). The Soviets were ready to launch during Cuba as well and then loaded up the bombs in 1983 just on a misinterpretation of NATO exercises. The only reason we never did it in those cases was because calm leaders prevailed.
Putin, from all I've been hearing, is not a calm leader. He's a tyrant anyway in normal circumstances but reports from Russia are that he feels more isolated than ever now and is not acting rational. His own inner circle didn't even realize he was serious about war until the last second.
They're holding back because if they turn Ukraine into a humanitarian crisis, the rest of the world gets involved.
I'm speculating but it's the only thing that makes sense
I honestly don't think the rest of the world is going to get involved militarily in Ukraine no matter what he does. I think he's trying to keep face for economic and political reasons, both internal and external.
His narrative was that Ukraine isn't even a real country and the Ukrainians want to be part of Russia anyway. He wants to maintain that narrative in global eyes in order to keep his allies with him and in local eyes to keep the Russian people in support of him. Sending in a relatively small force and winning quickly with few casualties would help advance that narrative. That's the gamble he took.