If Nasir al-Wuhayshi was killed—a claim that U.S. officials are so far not disputing—his death would be a significant blow to the already fragile al Qaeda terrorist organization. And it would be the second major hit in a matter of days on a key al Qaeda leader, following a series of U.S. airstrikes over the weekend in Libya that killed another notorious jihadist, Mokhtar Belmokhtar.

Wuhayshi is arguably the bigger prize, having been promoted two years ago to run all of al Qaeda’s global terror attacks. U.S. intelligence officials have said that his division, al Qaeda in the Arabian Peninsula, or AQAP, has been perfecting methods for sneaking explosives onto airplanes, hidden inside devices that don’t alert security screening systems.

In other words, as far as the U.S. intelligence community is concerned, Wuhayshi is al Qaeda’s No. 1 threat. If he is gone, it would be seen as a major win for American counterterror operations.

Reports emerged Monday on Twitter from purported AQAP members mourning Wuhayshi’s death and praising his already named successor, Qassem al Rimi.