The mechanism - neutron flux from the first bomb pushing the second into criticality - seems plausible.
Where does it say that this is impossible?
Where does it say that this is impossible?
Still not great of course! Now you’ve spread the second bomb’s worth of Pu or U over a wide area with the energy of the first one. Toxic /and/ radioactive. What’s not to like!
(I may have been digging up a partial memory of muclear missile fratricide by Pu predetonation during compression due to the extra neutron flux, which IIRC is a real thing, but would require the second warhead to go through a full conventional explosion.)