Michael G. Vickers, the undersecretary of defense for intelligence, said at a defense conference that if the current pace of U.S. operations continues, “within 18 to 24 months, core al-Qaeda’s cohesion and operational capabilities could be degraded to the point that the group could fragment.”

Vickers’s remark represents the first time that a senior U.S. official has offered a time frame for achieving the collapse of the organization responsible for the Sept. 11, 2001, attacks. His comments were consistent with assessments delivered to Congress on Tuesday by the nation’s top two intelligence officials…

Petraeus described al-Qaeda in the Arabian Peninsula, one of the affiliates, as “the most dangerous regional node in the global jihad” and said that the CIA has seen new signs of “al-Qaeda’s efforts to carry out relatively small attacks that would . . . generate fear and create the need for costly security improvements.”