Russia tries to keep Poland, Baltic states and other unfriendly bordering nations from getting involved in any military action against Russia by making it clear that response will be nuclear.

The desire to involve other nations against Russia goes up with Ukraine slowly loosing war against Russia. Tactical encirclement of 72nd Ukrainian battalion in Ugledar is the most recent example of losses on Ukrainian side.

Change to Nuclear weapons doctrine tries to stop opening of 2nd war front against Russia. The most likely location would be border between Belorussia and Poland.