WASHINGTON -- Top federal security officials said Tuesday that the terrorist threat to strike the U.S., first disclosed on the eve of 9/11's 10th anniversary, remains unresolved.
Homeland Security Secretary Janet Napolitano, FBI Director Robert Mueller and National Counterterrorism Center Director Matthew Olsen told the Senate Homeland Security Committee that heightened security levels would be maintained in Washington and New York— the cities targeted in the alleged vehicle bomb threat.
"We are not prepared to say it is resolved," Olsen told the panel, the first public comments since the threat was publicly disclosed Thursday.
Last week, U.S. authorities said they were investigating a specific and credible lead from a reliable source in Pakistan outlining a scenario in which three individuals were sent to the U.S. to carry out vehicle bomb attacks in Washington or New York around the time of 9/11's anniversary.
The information remains uncorroborated and there has been no evidence that the persons successfully entered the country.
Mueller said "hundreds" of interviews have been conducted over the past several days, resulting in the "elimination of some aspects'' of the threat. But he said more work needs to be done.
The FBI director said the threat is being evaluated as part of a increasingly "complex" environment in which terrorists are striking out on their own, apart from al-Qaeda and other long-standing terror organizations, all weakened in the long fight since Sept. 11, 2001.
Olsen said al-Qaeda's core has been "weakened" with the death of Osama bin Laden and other leaders, though it has demonstrated an ability to adapt.
Bin Laden was killed in a May raid on a Pakistani compound, where he had been living for years while the U.S. pursued him after the 9/11 assaults.
"Al-Qaeda is weakened, but not vanquished," Olsen said.