[arethuza]

"Residual radiation of fragments wouldn't be expected, as the Gazelle system uses neutron bombs"

"Neutron bomb" is another name for an "enhanced radiation weapon" - basically an H-bomb designed to give off large amounts of neutron radiation. So you would expect anything close to the explosion of such a device (and therefore exposed to a very high neutron flux) to have pretty clear indications that would be easy to test for.