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

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In response James Dean to his Publication

I 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.