with nukes you can regulate the inputs because its physically impossible to build one without uranium or some other fissile material. they also give off radiation making it easier to detect. its hard to make them in secret when you need mines, big enrichment facilities and years of research with hundreds of engineers where just one of them can leak the whole thing.

training llms only takes compute and memory. two things that are basically everywhere. even if you somehow stopped making new gpus today theres still millions of them out there and its possible to start a secret production line. you can maybe try some controls at the tooling and chemical level but look what happened with asml and huawei.

the only thing you can really do is find and stop large data centers that are built out in public. nothing outside of political pressure works against secret operations in a fortified bunker or any form of distributed training. if a "rogue state" like north korea decides to make skynet they will eventually get it as long as their engineers know what there doing.

and the best way to fight bad X {ai, tech, religion, politics} has always been good X, not no X. in this case thats open source models, coming out of china or europe or anywhere else. thats the real answer.