> And what ability do you see us as having to restrict Chinese viral research?

The ability to appeal to their self-interest? I doubt that any evidence would cause the CCP to deviate from its preferred story (which I think now is natural zoonosis outside China, then import on frozen food?), but they don't want a pandemic any more than I do.

So I'd guess that given evidence that certain research activities likely caused this pandemic, the Chinese government would quietly act to restrict them, all while publicly denying that they're doing so. Indeed, they might have already--Dr. Shi's group hasn't published anything even as dangerous as these BU researchers' experiment since before the pandemic.

Is the work complete then? Or would the investigation need to continue? And what sort of evidence would it take to conclude?

I do think it's possible that Chinese virology is safer than American virology now. The latter doesn't seem too safe though, judging from the work at BU that we're discussing here.

As noted above, I believe that subpoenas should be obtained for all relevant records of the WIV's collaborators, and for any sequencer reads that potentially contain early viral genomes as contamination. The evidence for a lab origin so far is scattered and circumstantial, but that's just from various leaks and amateur open source intelligence; perhaps a formal investigation with subpoena power could learn more.

We’ve restricted Chinese nuclear weapons tests just fine.

Have we? I'm far from an expert, but doesn't China have a mature nuclear program that includes enough of an arsenal for their strategic purposes?

It does not seem that we've been able to contain the ambitions of North Korea, and Iran isn't looking so good either.