I think the thrust of the issue is that the US has agreed to certain "rules" like the Geneva convention and such. And among those rules are to NOT use bioweapons. Now, if we were doing it on our own soil, that's our jurisdiction and if any foreign entity steps foot on US land, I'll take up arms myself against them.
What matters to me here, and I think is the important thing is that if the US government has transgressed agreed-upon rules, if the US has resorted to developing bioweapons (and potentially using them), then someone has to answer to it.
I would not be against grabbing certain accused politicians and others, and putting them in front of a tribunal at a neutral location. Or trying them within our own systems, but with allowing testimony and evidence from foreign entities. Although my trust for our system is rather low, I don't think any world court would be any better. Finding impartiality is the hard part.
gisd O