I was thinking more of the use of other types of mass destruction, such as chemical or biological, which could fall into the wrong hands - and it is possible that a nuclear attack with a home-made bomb can happen at any time. States are very cautious on this issue because they know that any attack will provoke a sharp counterattack and that no one emerges victorious from a nuclear war.
You must be familiar with the movie The Peacemaker, so even though it’s just a movie, if anyone had the desire to do it, I believe it would be feasible today. Of course, the question is how to get to the most important components - but given what is happening in Russia - Russian 'doomsday' plane's radio equipment stolen by thieves, I think anything can be bought or stolen for the right price.
The fact is that there is a huge amount of weapons of mass destruction, and that is a huge risk given that there are always those who would be happy to use them against their enemies.