IF it was Russia who sabotaged the Nord Stream pipelines (that have been closed since the start of September), I suggest it's to show that he could also bomb the pipelines from Norway.
That WOULD be constituted as an act of war. I do not see the US sending nuclear weapons or even troops, but I can imagine a lot of F15s & F16s being supplied (the US is trying to sell of a lot of those second hand. It's maintenance that is key.
I like the way Jeffery Lewis judges Putin. He notes that President Putin enjoys his large homes, his collection of vintage watches, fine food and generally 'the good life'. So he can quit if he has to because it's almost certain that Nikolai Patrushev would replace him and Mr. Patrushev would ensure that Mr. Putin would not face any court, lose any of his wealth or otherwise be inconvenienced.
I note that VPNs like SurfShark have seen a 5400% increase in Russian VPN use. So conscription has seen a lot of Russians looking at the news from other nations - most especially news channels from non-aligned nations who support neither Russia nor The US/NATO. We HAVE begun to see very obvious propaganda that is designed to make it clear that while Russia might win a long, drawn out war, it might cost a huge number of lives. Russians will fight for the survival of their own nation, but they aren't quite as keen to die in a war that did not need to happen.