There were reports of the Russian Mafia having control over nuclear material. [1] The collapse of the iron curtain caused a wonderful climate for well funded criminal elements to get their hands on all sorts of nasty stuff. This is documented, but not really discussed that much. I've read that many governments are actually a lot less worried about the Russian mafia having this material than they are about North Korea having these weapons, as organised crime doesn't really stand to profit very much from a nuclear stand-off. Apparently Mossad even purchased some of it to "stop it falling into the hands of Islamic and other terror groups" [2]
You can't put that genie back in it's bottle. The Nuclear Age won't be over for a while yet, it's just in a quiet phase.
[1]: https://www.law.upenn.edu/journals/jil/articles/volume16/iss...
You do realize Japan attacked Pearl Harbor because we were waging economic war ("leverage") on them? Such as the oil embargo?