While I take the threat of a nuclear yeild seriously, I suspect that the parameters needed to effect an explosive yeild would be too difficult master.
I have always been under the impression that so many things must be "just right" for there to be a blast.
Yes? No?
There are supposedly about 100 "suitcase nukes" (small nuclear weapons in a large container--just barely able to be carried by someone) missing from the former Soviet stockpile. I would tend to think that al Queda must have some of them by now, why else would Osama bin Laden go asking for religious "permission" to use nuclear weapons from a Muslim cleric in Saudi Arabia? Houston, San Francisco, Chicago, Denver, Los Angeles, Seattle, Washington DC or NYC would be the most likely targets, IMHO.
You've not heard of back pack nuclear weapons.
"I have always been under the impression that so many things must be "just right" for there to be a blast."
Unfortunately, this is not the case.
An implosion type plutonium bomb is very difficult to properly trigger, but this is not the case with an enriched uranium bomb.
It really only takes two subcritical masses of enriched uranium placed at opposite ends of a "gun barrel" type bomb
fired at each other with high explosives.
The timing devices to ensure proper timing of the detonation of the HE are critical, but not nearly so critical as plutonium bombs.
A crude device of this type could produce a nuclear detonation.