This is the absurd logic of a beast empire.
First it invades a sovereign country calling it a "special military operation" - claiming this was to "protect the people" of the Russian-controlled breakaway republics.
And then, when Ukraine is given permission to strike legitimate military targets in Russian territory with long range weapons provided by a third party nation (U.S.A.), Russia threatens a nuclear response.
All the while, the Russian Foreign Minister (Lavrov) is saying that Russia "does not want to see a nuclear war".
I suspect that Russia, if it remains intact until then, will be one of the ten horns in that last days coalition of nations described in Daniel 7.