The Bush Administration may have overreacted to this threat

Remember Jose Padilla, the wannabe dirty bomber? Here's the New York Times on the extent of the threat he posed:

Abu Zubaydah, the first Osama bin Laden henchman captured by the United States after the terrorist attacks of Sept. 11, 2001, was bloodied and feverish when a C.I.A. security team delivered him to a secret safe house in Thailand for interrogation in the early spring of 2002. Bullet fragments had ripped through his abdomen and groin during a firefight in Pakistan several days earlier when he had been captured...

In his early interviews ... Mr. Zubaydah also identified Jose Padilla, an American citizen who has been charged with terrorism-related crimes.But Mr. Zubaydah dismissed Mr. Padilla as a maladroit extremist whose hope to construct a dirty bomb, using conventional explosives to disperse radioactive materials, was far-fetched. He told his questioners that Mr. Padilla was ignorant on the subject of nuclear physics and believed he could separate plutonium from nuclear material by rapidly swinging over his head a bucket filled with fissionable material.