[DB]

I do not believe you are correct.

I do not believe we can detect a nuke from any significant distance when reasonably shielded.

For example if one is placed at the bottom of a filled oil tanker I seriously doubt we would have much luck at all detecting it.

That is prior to detonation…

[dark_lord]

You may be right. Fortunately, the lousy persian golf oil tanker smugglers don't come to our shores. The big tankers are run by the oil companies and they have sufficient security to prevent someone from sequesting a nuke. Not easy at all to do that. Would require quite a bit to get one on board undetected, I think; and require replacement of the crew with suicidal fanatics who would have to successfully sail the ship for several days to get it to our shores. Pretty risky for them.