Most feared nuke is crude but deadly

NEW YORK -- Among terrorist weapons experts worry about, one device tops the list: the atom bomb.

While chances are remote that a terrorist might obtain one of the suitcase-sized nuclear bombs produced by the United States or former Soviet Union, analysts worry that a crude but deadly device might be fashioned from stolen nuclear material and a few sticks of dynamite.

Such a radiological bomb wouldn't yield a nuclear explosion but rather a plume of toxic radiation.

"Had the terrorists at the World Trade Center used a radiological dispersal device, most parts of lower Manhattan would have been rendered uninhabitable," said Tariq Rauf, director of the nonproliferation program at the Monterey Institute of International Studies.

Such a bomb requires neither knowledge of physics nor the rigors of smuggling weapons-grade uranium or plutonium.

"It's not that hard to build a radiological bomb since all you have to do is disperse a bunch of radioactive material," said Michael O'Hanlon, a fellow at the Brookings Institution.

1,000 places

Highly radioactive material is stored at over 1,000 facilities in 50 countries, according to the Carnegie Endowment for International Peace. The group says some facilities muster insufficient security against would-be thieves.

America's defense against nuclear smuggling consists of pressuring countries to bolster safeguards on weapons-usable and radioactive material, along with boosting border defenses in the United States and in countries on likely transit routes.

Analysts who've examined the threat describe three separate scenarios.

In the first, a so-called "suitcase nuke," probably from the ex-Soviet Union, could be sold to terrorists, who would seek to smuggle it into the United States, or within range of an U.S. overseas interest.

"I'm not overly concerned about the suitcase bomb threat," said Jon Wolfsthal, an associate with the Carnegie Endowment for International Peace. "The U.S. intelligence services have very high confidence that Russia has accounted for all its nuclear weapons."

A second scenario involves a terrorist group building its own nuclear bomb using smuggled nuclear material.

The International Atomic Energy Agency has documented 18 cases of weapons-grade nuclear smuggling since 1993, among hundreds of cases of trafficking in radioactive materials. None of the cases involved enough for a bomb.

Hard to track

About a dozen countries have the material, but the largest amount -- some 1,300 metric tons -- sits in Russian weapons facilities and laboratories, according to the U.S. Department of Energy.

"It's very hard to track," Wolfsthal said. "The Russians themselves don't know themselves how much they have."

Still, a terrorist-made A-bomb is a low-probability threat.

"Even Saddam Hussein's weapons program, after 10 years and several billion dollars in investments, was not able to make a nuclear bomb," Rauf said.

The radiological bomb is a much simpler matter.

Depending on its potency, a contamination-spewing radiological bomb could kill dozens, hundreds, possibly thousands. Its toxic plume could render a square mile or more uninhabitable for a decade or longer. .

"To a terrorist who is trying to create widespread panic, this option is more appealing," Rauf said. "You can see the white powder of anthrax, but not radiation."