Comment by tyre

It takes a lot of centrifuges to refine the amount and, more importantly, the purity of fissile material. By the time you need them, it would take a long time to spin up that infrastructure and iron out the kinks.

It’s not a casual undertaking and other nations will know you’re doing it. The major global powers are not interested in more nuclear weapons, not only to maintain their hegemony but also to limit the number of parties that could cause massive issues. Not to mention the likelihood that a national or political shift could mean nukes in the hands of those less…restrained.

Plus it raises the surface area of others gaining access to the material or capabilities. Proliferation is bad for the world, generally.