It is also essential to ensure that terrorists do not attempt to come into the United States aboard the roughly 6 million cargo containers entering U.S. seaports each year, Customs Commissioner Robert Bonner said.
More is needed beyond tight security at U.S. seaports, land borders and other points of entry into the United States, Bonner said Wednesday.
"That's the last line of defense," Bonner said. "That's the reason ... I have proposed that we essentially move our zone of security outwards.
"That we actually have a strategy for searching and inspecting containers that are high risk, for example, at the point of origin, rather than the point of arrival — rather than waiting for the container to come in to the Port of Baltimore."
Under a recent agreement with Canada, U.S. Customs has put inspectors in Montreal, Halifax and Vancouver to screen cargo headed for the United States. Canadian Customs officials have inspectors at some U.S. seaports.
Bonner hopes to have similar arrangements worked out with other countries in the coming months, possibly including Singapore, Japan, France, Germany and the Netherlands. "I am cautiously optimistic," he said.
Fears of a terrorist nuclear assault on the United States have risen since the Sept. 11 attacks in New York and Washington.
Bonner said he knows of no terrorist group trying to smuggle a nuclear device into the country.
"The question is, `Should we be concerned about it?"' he said. "This is one of those areas where I don't want to wait and see what happens."
Since Sept. 11, Customs has shifted its primary mission from detecting smuggled narcotics to stopping terrorists, possibly with nuclear, chemical or biological weapons, from getting into the country.
Specifically, Customs has increased security and provided better training for its inspectors and agents at seaports, airports and border crossings on land. Customs oversees roughly 300 points of entry into the United States. It also is looking to use more sophisticated scanning and detection technology at seaports and land crossings.
Still, "there are no guarantees" that such measures will stop a terrorist from smuggling in a nuclear weapon, Bonner said. "No system is foolproof."
Bonner, a former federal judge and chief of the Drug Enforcement Administration in the early 1990s, was sworn in as Customs commissioner on Sept. 24.
U.S. intelligence, Bonner said, believes Osama bin Laden's al Qaeda terror network is "determined to strike the United States again. ... That much is clear.
"We don't know if al Qaeda or related terrorist organizations have a nuclear device," he said.
"What we do know is that for at least the last five or more years they've attempted to get ... radiological materials to build a nuclear device. They consulted with a Pakistani scientist or engineer who was involved in the Pakistani nuclear development," Bonner said. "Certainly there's been an attempt to get a device."
Although bin Laden claimed on a videotape to have a nuclear device, Bonner said, "I don't believe him."
Even with the shift in its mission, fighting terrorism isn't new to Customs. The agency was credited with thwarting a terrorist attack before the millennium celebration.
Customs inspectors stopped an Algerian man at the border at Port Angeles, Wash., in December 1999 and found more than 100 pounds of explosives in the trunk of his car. The man had trained in terror camps run by bin Laden.