what stops countries from secretly developing nuclear weapons?

Question

What I mean is that nuclear technology is more than 60 years old now, and I guess there is a pretty good understanding of how to build nuclear weapons, and how to make ballistic missiles. So what exactly stops countries from secretly developing them in remote facilities?

In: Other

Answer 1

It’s very expensive.

It’s hard to hide hundreds billions dollars going for secret nuclear weapons program, countries that are big enough to do it already have nukes.