ISLAMABAD, Pakistan — A Central Intelligence Agency drone strike in Pakistan’s tribal belt killed Al Qaeda’s deputy leader, Abu Yahya al-Libi, American officials said on Tuesday, dealing another blow to the group in a lawless area that has long been considered the global headquarters of international terrorism but the importance of which may now be slipping.

Mr. Libi’s death would be another dramatic moment for an American covert war in Pakistan that has been particularly active over the past year, starting with the death of the group’s founder, Osama bin Laden, in May 2011 and followed up by drone strikes against several senior lieutenants, including Atiyah Abd al-Rahman.

But that very success could, paradoxically, signal a shifting target: as Al Qaeda’s leadership in the tribal belt has been cornered or killed, new efforts to attack Western targets have been mounted by the group’s affiliates in Yemen and Somalia.

Unlike many of the relatively unknown figures killed in other drone strikes, Mr. Libi, who had a $1 million bounty on his head, was a virtual ambassador for global jihad. An Islamic scholar by training, he used frequent video appearances to expound on world events, chastise critics and boast about his escape from an American military prison in Afghanistan in 2005.