Bill Stewart writes:

Meanwhile of course, any foreign terrorist that wants to nuke the US with a physically small weapon only needs to pack it in cocaine and bring it in with the regular shipments, while Rogue Nations that can only make large Fat Boy style weapons need cruder methods, like bribing a crane operator to load the wrong container on a ship bound for New York or Los Angelese harbor.

It may not be that easy. My understanding (based on various TV programs broadcast back in the early 90's) is that there is a program called 'NEST', which stands for something like Nuclear Emergency (mumble) Team, tasked with dealing with this type of problem. One protection hinted is that strategically chosen points of transit (bridges, ports, tunnels, major highways, mail, baggage and freight facilities, etc) have detectors for nuclear materials. The thing is, while you can sheild a source to the point where it is not a hazard, sheilding it to the point of *undetectability* is far harder task. If you detect even a single gamma ray of a certain frequency, or betas or even alphas of certain energies, you *know* that a certain isotope produced them. If the detectors note the presence of a certain isotopes, they generate the appropriate alarms. There are also other detection systems - I've seen X-rays of entire container trucks which were passing through the Chunnel - illegal immigrants were quite visible inside the container. An attacker's best chance would be to place his weapon in a container, heavily sheilded, and then to bury that in the middle of a stack of other containers of heavy shielding in the hold of a container ship, and plan to detonate it while still on board in a target harbor. UPS probably would not work (besides, I think they have a limit of around 90 lbs). Peter Trei