[Tacis]

Probably nothing more than the residual radioactivity from a prior cargo. This may have been one of the ships that dropped the nukes/nuclear material in Havana. From there, it goes to Mexico and then, across the border into the US. The Mexican military, if paid enough, will move anything north, drugs, currency, illegals, or nukes. We don't give a big rat's a** about the dangerous material coming north, why should we care what goes into Newark?

[Diogenesis]

Why should there be residual radioactivity, unless
the ship previously held a neutron source? or if some radioisotope
was STILL present.

Good job picking this up. Who put the cargo on board?