/diy/ - Do It Yourself

(This question should be on /sci/, but that board is a joke and you guys have a lot of expertise on industrial/fabrication-related topics.)

Why does North Korea, or any state for that matter, necessarily need to carry out physical detonations to test their nuclear weapons anymore? Computers have been powerful enough for a while now to simulate bomb yields using finite element analysis; in fact China has been doing just that in recent years,

Wouldn't it be a lot easier and a lot less reckless for the North Korean regime to simply construct a supercomputer on which to develop its weapons, versus alarming the world by constructing and detonating physical devices?