The reality is that European solidarity is not ironclad either. Is the US, or Germany, or Sweden more likely to fold and deactivate* weapon systems under nuclear blackmail?

It sounds hypothetical but seriously, what would Gripen do if tactical nukes were dropped on Estonia and Putin threatened the same on Sweden if they didn't back off? I don't know, and you don't either.

*I've not seen credible accusations this is possible, but assuming it is