I'm not sure. It is impossible to theorize what Russia would do in the wake of that kind loss, nor is it possible to theorize the conditions that would trigger the use of nuclear weapons and in what way. The last time nuclear weapons was used was in a very different situation, and with radically different technology, and thus with radically different policies.

As with the build up to the invasion in late 2021, I think we would see much more happening before something as serious as that occurs; it is difficult to truly hide your intentions in today's world with the technology we have.