There's just no way that there isn't retaliation. We're still operating under MAD. Between air force, Navy, and ICBMs, there's too many nukes on both sides that dozens but more probably hundreds of millions of people would die. The entire point of the Ukraine war is to prevent NATO from getting any closer and possibly sticking nukes (or targets that would invoke a nuclear response from NATO) within striking distance such that retaliation couldn't occur in time to sustain MAD. It's very similar to the Cuban/Turkish standoff that occurred at the height of the cold war. I see the change in doctrine more matching the US' first strike policy and Russia trying to assert itself as a world power again. They're putting those words into action with their current military endeavors and diplomatic moves, but statements like these are continuous opportunities for the West to pull their heads out of their asses and recognize the change in reality beneath them.