I don't see any evidence that Russia is broadly retreating. Evidently they have retreated where Ukraine had a strong offensive but it would be a remarkable coin

I don't see any evidence that Russia is broadly retreating. Evidently they have retreated where Ukraine had a strong offensive but it would be a remarkable coincidence if that was the bit that they were planning on nuking. And only that bit. And if they were planning on using nuclear weapons, why would they nuke the parts that they control? Surely it would make more sense to attack Kyiv and other centres of command and control. Maybe they will use nuclear or other mass destruction weapons but nothing that they have done (as against said) so far is consistent with that. Everything has been consistent with permanently annexing highly productive parts of Ukraine.