Brennan: WH leaving no stone unturned on threat

Chief White House counterterrorism adviser John Brennan on CBS' "Face the Nation," September 11, 2011.

John Brennan, chief counterterrorism adviser to President Obama, said Sunday that a possible terror threat tied to the anniversary of the Sept. 11 attacks remained unconfirmed but that the administration is doing "everything possible" to track down any information associated with the reports.

Counterterrorism officials received information last week suggesting that al Qaeda may have sent three men to the U.S. to perpetrate acts of terrorism in New York and/or Washington, D.C. According to the tip, which came from a CIA informant in Pakistan who has in the past provided reliable information, two of the men may have been American citizens. The informant also said the possible attackers were of Arab descent and might speak both Arabic and English.

Brennan, appearing on CBS' "Face the Nation," said President Obama met with his senior national security team Saturday and instructed them "to do everything possible to pull these threads, to see about the information that's been provided to us, that is specific and credible." He said the national security team had convened again on Sunday morning in the situation room "to review all the available intelligence and to go over the actions that we're taking.

"Again, it's not confirmed, but the president wants to make sure that we leave no stone unturned. And that's what the intelligence, law enforcement, and homeland security communities are doing," Brennan told CBS' Bob Schieffer.

Brennan declined to get into "operational details" regarding the investigation, but said the administration does have "some information about the nature of the attack that is being reported," as well as "some information about the possible individuals."

According to the informant, the men were on a mission to detonate a car bomb in either Washington, D.C. or New York.

Brennan emphasized that the administration was pursuing the leads vigilantly.

"We are looking at travel data, other types of pieces of information and trying to correlate them against other reporting that is coming in," he told Schieffer. "We are doing everything possible to see if we can find any additional information that would give us a lead about where these individuals, if they do exist, if they are planning to carry out an attack here in the States, may be residing right now."

"Again, it's not confirmed but we're not relaxing at all," he added. "This is a 24/7 round the clock effort by all elements of the U.S. counterterrorism community both here in the United States as well as abroad."