Trouble is (for them, not us), they're building #1. While it may well be based on plans provided by an outside source, as al-Qaida found out, you better know where those plans are coming from.
(From Southack)Then once you've got it, you still need to know how to work on a metal (Uranium and Plutonium are metals) that is extraordinarily brittle and hot, yet needs to be machined to tolerances more demanding than aircraft parts. How many nations on this planet can even manufacture mere aircraft parts? Not many.
Actually most aircraft parts have extremely sloppy tolerances. I know first hand that Cessnas will happily chug along with ice or goose sized holes on the wings. Unless you mean the tolerances for jet engine parts. Mass producing is hard, yes, but any decent physics grad. student can do .0005" without much trouble. Furthermore, I wouldn't be surprised if pre-machined parts are on the market. Everything else is in Moscow. I saw CD ROM's of the Moscow police databases for sale on the street. Officier's names, home addresses, case info.
Depending on the design, tolerances are somewhat fungible. Of course, the looser the tolerance, the larger the bomb must be in order to work.
Regarding working uranium/plutonium, they ARE extremely hard to work. Not only are they brittle/hot (and in the case of plutonium) toxic, but they are EXTREMELY dense (very hard to cut) and their densities are variable (under certain non-explosive conditions, a non-critical mass of uranium/plutonium will reach critical mass).
I don't know where the reference to Moscow police databases come from, though.
(More Southack)Refining U235 is a nasty process, and getting Plutonium requires a breeder reactor.
Why refine? Russia and Central Asia are awash in these materials
And there's honor amongst thieves? Ask al-Qaida just how trustworthy their nuclear sources were. From what I remember, the Russian Mafiya gave them some materials that was just radioactive enough to do a few clicks on the ole' Geiger counter.
There's not all that much fissionable uranium that is naturally-occuring (and no natural plutonium). In order to make a functional nuclear device, you need somewhere near 99%-pure uranium or plutonium (and that 99% had better be the right isotope). (More Southack)Then once you've got all of that figured out, you've got to have electronics that can withstand intense radiation, and in at least one case, must be extraordinarily well-timed.
Either half of Iraq has kidney stones or they have been buying medical equipment to scavenge electronics for a plutonium implosion device. A U-235 gun requires no electronics at all. You could build one that employed a flint-lock if you had a perverse sense of techno-irony.
But you can't load a uranium gun bomb onto a missile and have anything resembling a decent yield. Without a reliable and timely detonation, the remainder of nuclear weapons designs are nothing more than radioactive firecrackers with not all-that-much conventional explosives to do serious damage.
The USSR refined enough of both for thousands of devices. These materials are now guarded by starving lice ridden Russian soldiers too young/malnourished to shave.
But you can't load a uranium gun bomb onto a missile and have anything resembling a decent yield. Without a reliable and timely detonation, the remainder of nuclear weapons designs are nothing more than radioactive firecrackers with not all-that-much conventional explosives to do serious damage.
Little Boy's design was so straightforward it was never tested. No timing is required unless you want to add neutron triggering for more yield. 10-20 ktons is pretty much a "firecracker" by modern standards but is more than enough to jack up an urban area. No missle required, thousands of cargo containers enter the US everyday from around the world. If we can't even get a pea shooter in a cockpit in 365 days, how long will it take to get Geiger counters at all of our ports.
Bio's are simpler, more available, and more dangerous. I wouldn't be surprised by the democratization of u-235 guns as well.