If Ukrainian forces enter Crimea it's overwhelmingly likely that it's as part of an effort to take back Crimea. In that case you have to ask yourself watch the probability that Putin assesses that the Ukrainian offensive will be effective. If Russia uses nuclear weapons over Crimea it's likely to be before Ukraine captures large amounts of territory rather than at the end of the Ukrainian operation to recapture Crimea so I would also make the forecast here.
To mark a year since Russia’s full-scale invasion of Ukraine, Galen Druke brings back two experts who first joined the podcast when the war began. Samuel Charap is a senior political scientist at the RAND Corporation and author of the book “Everyone Loses: The Ukraine Crisis and the Ruinous Contest for Post-Soviet Eurasia.” James Acton is a physicist and co-director of the Nuclear Policy Program at the Carnegie Endowment for International Peace. Together they describe why the war has not turned out as originally expected, what the risks of escalation are today and how the conflict might come to an end.