US fears attack using nuclear, biological weapon

WASHINGTON, Sep 7 (Reuters) While most Americans focus on the threat of another aviation attack like the September 11 hijackings, the U S government is quietly working to prevent something far worse -- a catastrophic strike with a weapon of mass destruction.

Five years after the September 11 attacks killed nearly 3,000 people, Homeland Security Secretary Michael Chertoff has once again bolstered aviation security in high-profile fashion in response to a failed plot in Britain to blow up U S-bound planes.

But in a sign he fears other, more devastating attacks, Chertoff has also made his department focus on worst-case scenarios which could include nuclear or biological weapons.

Some analysts say the government is still not spending enough money to address such threats.

''An improvised nuclear device would be devastating with potentially hundreds of thousands of casualties and ... the damage would run in the trillions of dollars,'' said Vayl Oxford, director of the department's Domestic Nuclear Detection Office.

''One of the concerns we have is that a weapon could be manufactured inside the U S,'' Oxford said. His office is trying to protect against such a US-built weapon being brought into locations such as major cities where it could cause a great deal of damage.

The department this year began buying modernized equipment to scan cargo at ports and border cities for nuclear material -- with equipment still in use at many sites, ordinary substances such as cat litter can set off radiation alarms.

Another concern is what experts fear is becoming a global nuclear arms race.

''That just increases ... the potential that the technology will find its way to terror organizations,'' said P.J. Crowley, a spokesman for the U S government and military for 28 years who is now director of national defense and homeland security at the Center for American Progress.

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