Putin may be evil but I don’t think he is stupid. He floated the nuke issue to see what the response will be. It sounds like he got his answer and not in a way good for him so the real question is how does he up the ante without risking an overwhelming response that will be unrecoverable by Russia.
I think the sabotage of the Nordstream pipe line is a signal of his intent to go after European energy infrastructure. There is lots of room for mischief with wink wink nudge nudge deniability.
If he can get the EU to crack he thinks he can leverage imposed negotiations on Ukraine with terms favourable to him…..