spat
.700 Nitro Express
I believe we know with near certainty. We would also know if it was a stolen Soviet warhead.I assumed a missile launch for the EMP.
Yes, the nuke fingerprint could tell you a source if that source material was on file( which reactor created it). But what if it’s not on file ? Or was a Soviet era device ( refurbished). Are we going to launch against Russia not knowing if it was stolen when the Soviet Union collapsed. Or if Russia would launch more, regardless if they had something to do with it or not? ( we probably would do a B2/B21/cruise missile thing -but who knows) . Mutually Assured destruction isn’t as clear cut as it used to be.
We can even tell by flying a plane near an underground test hours after it happens. The technique is that sensitive and we spend a lot of money and manpower to build and maintain a comprehensive database.
Even for pure uranium weapons that never touched a reactor, we know who refined them.
People frequently talk about "well, if it's just one, do you want to go all out in response", but all the wargaming everyone has ever done shows that 100% it *will* turn into a full exchange eventually, and you are better off escalating as fast as possible.
Think of it like this, if you are arresting Bonnie and Clyde and you *know* they are going to resist with fully automatic gun fire, you do not yell "drop your weapons" and wait for them to shoot first.