Cheers, that's very interesting. I just found this too (from 2016), which backs up what you're saying https://www.wired.com/2016/01/science-can-tell-if-north-

Cheers, that's very interesting. I just found this too (from 2016), which backs up what you're saying https://www.wired.com/2016/01/science-can-tell-if-north-koreas-test-was-really-an-h-bomb/ https://www.wired.com/2016/01/science-can-tell-if-north-kore... It seems according to that, you could only tell from the radionuclides emitted as to what type of bomb it was. Interestingly there was a 500kt fission bomb - https://en.wikipedia.org/wiki/Ivy_King https://en.wikipedia.org/wiki/Ivy_King (but I assume experts must have a particular reason for thinking the DPRK detonation was a type of hydrogen bomb).