Clinton: Al Qaeda behind “credible but unconfirmed” terror threat

Secretary of State Hillary Clinton said Friday that al Qaeda is behind the possible terror threat the White House said it was running to ground.

"We are meeting here in New York . . . with the news last night of a specific, credible but unconfirmed report that al Qaeda again is seeking to harm Americans and in particular to target New York and Washington," Clinton said in a speech on counterterrorism to the John Jay College of Criminal Justice in New York Friday, Reuters reported.

Earlier Friday, Vice President Joseph Biden told ABC's Good Morning America the unconfirmed threat concerned car bombs.

"There are specifics, in that sense it was credible, but there's no certitude," Biden told Good Morning America (watch the video below). "There's no smoking gun, but we do have talk about using a car bomb."

The White House said President Obama was briefed on the specific threat information Thursday morning and had received updates throughout the day. "The United States government has already significantly enhanced its security posture in advance of the 9/11 anniversary to protect the country against possible terrorist threats," but is redoubling those efforts, a White House official told journalists by email Thursday night.

Former Bush White House counterterrorism advisor Fran Townsend suggested Thursday that the threat information may be coming from an al Qaeda operative, Younis al-Mauretani, who was reportedly arrested by Pakistani officials in Quetta, Pakistan earlier this week.

The threat info is "from overseas. Al Mauretani just arrested in Pakistan & Info is likely from him via the [Pakistanis]," she posted to Twitter. "If so, good sign of Pakistan [counterterrorism] cooperation."

Younis al-Mauretani "is a big get," White House counterterrorism adviser John Brennan told journalists Thursday at a breakfast sponsored by the Christian Science Monitor. But he cautioned against complacency, in the wake of the recent string of successful U.S. missions against al Qaeda leaders--most notably, of course, the US Navy Seal team's killing of Osama bin Laden in May.

"As you take out the so-called leaders, people move up in the system," Brennan said. "There are still a number of people in Pakistan who are determined to" plot attacks. "The job is not done there [in Pakistan] by any measure."