Another aspect of the nuclear thing is that nuclear material could be used without it being an actual fission bomb.
In the mid to late '90s there was a Scientific American article about problems with accounting for, and tracking of, nuclear material.
Apparently, at that time, (sorry, no cite), there was known to be missing or unaccounted for, about a pop/soda can’s worth of nuclear material. The article also stated that had that material alone been attached to the World Trade Center bomb (in the underground parking lot in the early '90s) it would have rendered a significant amount of Manhattan uninhabitable for thousands of years (or something of that magnitude).