The largest stocks outside the United States are in Russia and around the former Soviet Union, some in facilities with notoriously weak security and safety procedures.
"Once you have the fissile material, it's a matter of basic chemistry, basic machinery and a truck," said Holgate, now a vice president at the nonprofit Nuclear Threat Initiative. "You have to have some technical capability, but once you have those skills, it's certainly within the grasp of the kind of sophisticated, planning-capable terror organizations out there."
About This Series|
The three articles beginning today are the culmination of a year-long effort to examine the challenges the United States faces more than three years after the attacks of Sept. 11, 2001. Previous articles have ranged from the threat posed by conventional truck bombs to the difficulty of tracking terrorist fundraising. The articles starting today take a detailed look at terrorists' ability to acquire and use weapons of mass destruction -- nuclear, biological and chemical.
While the dangers certainly are real, there is considerable disagreement among security experts about the probabilities for "catastrophic terrorism." In the case of nuclear and biological weapons, the subjects of articles today and tomorrow, there are technical and scientific hurdles that have proved daunting, even for nations with sizable budgets and state-of-the-art facilities. Chemical weapons, which will be explored in an article Friday, would be somewhat easier to devise or obtain, but also far less likely to yield huge numbers of casualties. A radiological device would have similar limitations for terrorists.
Each type of weapon presents special challenges for the groups seeking to acquire it, but experts warn that the odds for a successful attack could rise significantly in the future as determined foes intersect with advancing technology.
_____The World After 9/11_____
Attack With Dirty Bomb More Likely, Officials Say (The Washington Post, Dec 29, 2004)
U.S. Unprepared Despite Progress, Experts Say (The Washington Post, Nov 8, 2004)
Va.-Based, U.S.-Financed Arabic Channel Finds Its Voice (The Washington Post, Oct 15, 2004)
Moroccans Gain Prominence in Terror Groups (The Washington Post, Oct 14, 2004)
From a Virtual Shadow, Messages of Terror (The Washington Post, Oct 2, 2004)
Facing New Realities as Islamic Americans (The Washington Post, Sep 12, 2004)
In Search Of Friends Among The Foes (The Washington Post, Sep 11, 2004)
U.S. Eyes Money Trails of Saudi-Backed Charities (The Washington Post, Aug 19, 2004)
Impervious Shield Elusive Against Drive-By Terrorists (The Washington Post, Aug 8, 2004)
Even so, there are a great many steps between obtaining the material and setting off an explosion. That may account for why such an attack has not materialized, despite intelligence warnings.
The uranium would have to be smuggled out of the facility and then transferred, possibly across several borders, seaports and airports, to a location where the device could be assembled. As described in unclassified literature, the gun-type bomb works when one mass of uranium is shot into another inside a tube. Such a device would be small enough to hide in a corner of a shipping container, but that would mean getting it to a port, onto a container and probably bribing a shipper or cargo crew to transport it.
An oil shipment would be optimal for a ready-made device, according to the congressional report, because the "size of the supertanker and thickness of the steel, especially with the use of double hulls," renders some detection equipment unusable.
But HEU emits low levels of radioactivity anyway, and that could be masked with lead shielding. A primitive device could be assembled in a small garage using machine tools readily available at an auto shop and concealed in a lead-plated delivery truck about the size of a delivery van, experts said.
It is also unclear how a terrorist group would know if its weapons development effort was on the right track. Nations with nuclear bombs conduct tests, including explosions that can be detected by scientists and governments. Bunn, who has published two studies on nuclear terrorism, said terrorists would not necessarily need to conduct such tests, but doing without them would increase chances that human error would foil plans or delay progress.
The most elaborate known effort by a terrorist group to develop a nuclear program was undertaken by the Japanese cult Aum Shinrikyo, which instead of stealing enriched uranium planned to mine and enrich the material itself.
Members of Aum Shinrikyo, intent on world destruction when it began its 1993 quest for a nuclear weapon, had all the means to pull it off, on paper at least: money, expertise, a remote haven in which to work, and most important, a private uranium mine.
But the group made dozens of mistakes in judgment, planning and execution. It shifted course, launching its chemical attack on the Tokyo subway in 1995.
"There are valuable lessons in Aum's experience, and there are false lessons," said Benjamin, co-author of "The Age of Sacred Terror." "The valuable lesson is that WMD terrorism is hard to do," he said. "But given that they didn't try what would be the most efficient way to put together a nuclear bomb, we shouldn't overrate their example as a reason why it's not going to happen."
Al Qaeda has been on the run since the United States deprived it of a haven in Afghanistan, making it more difficult for the group to operate on such an ambitious scale.
"At this moment, they are less capable of carrying out an operation like this because it would require so many different experts and operatives," Benjamin said. "But even a depleted group could do it if they got the right breaks."