Al Qaeda's new second-in-command, Atiyah abd al-Rahman, was killed earlier this week in Pakistan, US officials say.
The Libyan national rose to the number two spot when Ayman al-Zawahri took up the leadership of al Qaeda after Osama bin Laden was killed in May in a US raid in Pakistan.
Officials did not say how Atiyah abd al-Rahman was killed, but said it happened in Waziristan in northwest Pakistan where intelligence officials believe members of al Qaeda are hiding out, Reuters reports.
The BBC is reporting that a CIA drone strike was reported in Waziristan on the day the suspected al Qaeda operations chief was killed.
A US official said materials from Osama bin Laden's compound during the raid in May showed that Atiyah abd al-Rahman was already deeply involved in directing al Qaeda's operations and had multiple responsibilities in the organization.
Atiyah abd al-Rahman ran daily operations for the group, spoke on behalf of Osama bin Laden and Ayman al-Zawahri, and his death will make it more difficult for Zawahri to consolidate control, the official said.
US Defence Secretary Leon Panetta said last month that he believed the strategic defeat of al Qaeda was within reach if the United States could kill or capture up to 20 remaining leaders of the core group and its affiliates.