Why is it so hard to replicate the bulding of a nuclear bomb and why only a small amount of countires have them?

Question

Why is it so hard to replicate the bulding of a nuclear bomb and why only a small amount of countires have them?

In: Engineering

Answer 1

I don’t know anything about building nuclear bombs, but I think the problem isn’t necessarily the “know how”, it’s the ability to obtain enough quality fissile material in usable form

Edit: clarification