For example the new nuclear doctrine:

The doctrine now says an attack from a non-nuclear state, if backed by a nuclear power, will be treated as a joint assault on Russia.

https://www.bbc.com/news/articles/cj4v0rey0jzo

and a Russian lawmaker, when the EU parliament voted to allow all kinds of weapons to be send to Ukraine:

What the European Parliament is calling for leads to a world war using nuclear weapons

https://www.euractiv.com/section/defence-and-security/news/leading-russian-lawmaker-threatens-to-nuke-strasbourg-after-european-parliament-vote/