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Tom Ridge: Uncertainty biggest U.S. threat

WASHINGTON (CNN) -- Homeland Security Director Tom Ridge said the uncertainty of another terror attack is the top threat against the United States.

Ridge made the comment Monday during an interview with CNN. One possibility Ridge discussed is terrorist sabotage of a chemical facility.

"It is conceivable that instead of importing chemicals in the United States, they might find some way to use a pre-existing source right here in the United States against us as they have done with airplanes and envelopes."

VIDEO CNN's Jeanne Meserve conducts an interview with U.S. Director of Homeland Security Tom Ridge (December 17) Play video (QuickTime, Real or Windows Media)

Ridge was asked if there should be federal counterterrorism security standards for chemical plants.

"Because of the terrorist attacks, the companies themselves and the private security community have obviously upgraded. But as to date, we don't have any standards," he answered.

In the future, "we are going to have to have a standard."

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Some Americans have responded to the September 11 attacks by purchasing firearms. Ridge was asked about that phenomenon.

"The casual acquisition, the personal acquisition of a firearm I don't think is necessarily going to enhance national security," he said. "It may give an individual or family a greater sense of comfort, but at the end of the day that's not the best antidote to 21st century terrorist attacks."

Ridge was asked about reports in The Washington Post that the FBI found out about a CIA biological warfare program in recent weeks.

"One of the things that the president has commissioned me to do in his executive order is make sure that the gap, the delay in information-sharing no longer exists as we combat this war on terrorism."

When asked if this indicates that the gap still exists, Ridge said: "I think it indicates that I have got some work to do."