What is so difficult about developing nuclear weapons that makes some countries incapable of making them?

Question

What is so difficult about developing nuclear weapons that makes some countries incapable of making them?

In: 1394

Answer 1

Getting enough U-235 or plutonium together to make one. A gun-type device is fairly straightforward and dumb as a rock, even if it “just” levels a moderate sized city instead of flattening a 40km circle like the fancier setups. However the centrifuges for isotope separation are very expensive and very high tech – so, they aren’t sold in the Snap-On catalog and you can’t just stick one together with washing machine parts. They are purchased from a handful of companies in the US, Russia or Europe, and such purchases tend to make all the intelligence agencies go hmmmmmmm.