WASHINGTON (AP) - Director Leon Panetta says "one of the most aggressive operations in the history of the CIA" is disrupting al-Qaida.
      
Appearing today on ABC's "This Week," Panetta says al-Qaida is probably at its weakest since the Sept. 11 attacks because of U.S.-led strikes. He says there are likely only 50 to 100 militants operating inside Afghanistan and the rest are hiding along Pakistan's mountainous western border.
      
Panetta says the U.S. hasn't had good intelligence on Osama bin Laden's whereabouts for years and that the terrorist network is finding smarter ways to try to attack the United States. But he adds that if the U.S. can keep up the pressure, the CIA believes eventually it can "flush out bin Laden" and other leaders.
      
The rare assessment from the nation's spy chief comes as President Barack Obama builds up U.S. forces in Afghanistan.