Pulitzer Prize winner Steve Coll on nuclear terrorism.

At some point, perhaps after the expenditure of a great amount of money, it will probably be cops like these, and not scientists or defense theorists, who decide where radiation detection should rank on the long and diverse list of counter-terrorism techniques. The Department of Homeland Security recently announced an initiative to experiment with the installation of radiation detection at some bridges, tunnels, roadways, and waterways leading into Manhattan; later, the department hopes to surround other cities. The N.Y.P.D. fears that the sensors might prove to be too costly and would generate too many false alarms. Nearly three hundred thousand cars and trucks cross the George Washington Bridge in both directions on an average day; without an efficient way to process radiation alerts, a single convoy of banana trucks could jam up traffic for hours. "There are a lot of possible concerns that could surface with it," Raymond Kelly, the NYPD's commissioner, told me. Yet, he said, "we see this as something certainly worth trying." Kelly wants to deploy rings of sensors fifty miles or more from New York, so there would be a better chance of spotting an incoming device. In February, he held talks with his counterparts in Connecticut and New Jersey. Still, Kelly said, the entire project remains "very conceptual in nature."

See also this recent conference on the subject. No briefing materials are directly available, but the participant/speaker list is a good set of pointers.