Many students of terrorism believe that in important ways, Al Qaeda and its ideology of global jihad are in a pronounced decline — with its central leadership thrown off balance as operatives are increasingly picked off by missiles and manhunts and, more important, with its tactics discredited in public opinion across the Muslim world.

“Al Qaeda is losing its moral argument about the killing of innocent civilians,” said Emile A. Nakhleh, who headed the Central Intelligence Agency’s strategic analysis program on political Islam until 2006. “They’re finding it harder to recruit. They’re finding it harder to raise money.”