!!!
Agreed. The sea bottom along the path of the ship should be checked for anything unusual. Chances are the plan of terrorists would be to retrieve the "package(s)" at a later time.
Heck, a few years ago we found a damn 100+' SUBMARINE being built high up in Colombia for shipping cocaine to the USA! It was built in segments for road transport and assembly at the coast and was almost ready. A SUBMARINE.
Getting WMD into the USA is a joke. One 40 foot shipping container could be the equivalent of 20 OKC bombs, and set with a GPS trigger to detonate when crossing a certain bridge, or when being trucked across a city. (98% of containers are offloaded by automated cranes and never looked at inside until they reach Walmart etc.)