It's always a threat but no action from everything I've seen in the past they have never been able to set off a nuclear weapon.
Only hydrogen bombs which are made from water H2O, one hydrogen two oxygen.
1 gallon of water makes 133 gallons of hydrogen.
Anyone can make hydrogen it's fairly simple you can buy hydrogen generators on eBay but in the wrong hands they can do a lot of damage. This is why I believe the new hydrogen fuel cell cars may not be produced as they say they are.
https://www.newsweek.com/russia-issues-nuclear-threat-us-1964284
Russia Issues Nuclear Threat to US - Newsweek
The Kremlin has been ramping up its nuclear rhetoric in a bid to discourage Western support for Ukraine.
https://www.newsweek.com/russia-issues-nuclear-threat-us-1964284I don't think they have nuclear weapons. If they did, someone would have used it by now. I think they say they do to keep us afraid and compliant.