People come here with that kind of bullshit but none of those was a threat to any NATO member and none was an open invasion, but false flag operations, some casus belly, referendum or bullshit that gives Russia the narrative of the right to intervene or plausible deniabilty with soldiers disguised as rebels.

That's why Russia made the shit referendum and 90% of population in Crimea being Russian, and it never admitted to be in Donetsk region or fighting any war with Ukraine.

However, now it is different. There's no right, no reason and no narrative that gives excuse to not blame Russia to anybody that doesn't want to fight it, nor to Russia to invade Ukraine.
Putin's bullshit has been all exposed and whatever he does now will be shown as it is. Maskirovka no longer works, and everybody knows what he has been doing, who are friend and enemies and have to pick up sides.

Any further intervention in Ukraine by Russia will be presented as it is, no longer as an ethnic rebellion but as an invasion.

And believe whatever, NATO will step in, and it won't be even to help Ukraine but to stop Russia from crossing the Dnieper river. No matter what people believe, the economic consequences, or what politicians say to the cameras. NATO already has a presence in Ukraine to deter Russia from invading, through soldiers in "training" and conflict monitors that Russia wouldn't risk to cause any arm. But the moment that the Russian army would cross the border into Ukraine and start attacking in land not held by the "rebels" NATO will mobilize to the borders of eastern members and into Ukraine along the river Dnieper.

The thing is, Russia won't dare because it knows that NATO no longer can just stand and watch.