WASHINGTON (AP) - U.S. counterterrorist officials warn that al-Qaida's leaders still dream of payback for the raid that killed Osama bin Laden a year ago.

The officials say U.S. strikes against have all but dismantled bin Laden's old team and left the terror network too busy surviving to carry out another Sept. 11-style attack. But they note that new branches are hitting Western targets and U.S. allies overseas.

The deadliest is in Yemen. White House counterterrorism advisor John Brennan tells ABC's "This Week" that the al-Qaida's Yemen branch continues to target Americans in the Gulf nation and still aspires to attack the U.S.

Brennan says there's no sign of an active revenge plot against U.S. targets, but U.S. citizens in Pakistan and elsewhere are being warned to be vigilant ahead of the May 2 anniversary. U.S. helicopters swooped down in a nighttime raid on bin Laden's compound in the Pakistani army town of Abbottabad (AHBT'-uh-bad), killing him, one of his sons, two couriers and their wives.