Al Qaeda’s branch in Yemen is surging in strength, finding new support and recruits among the country’s Sunni tribesmen, in a backlash to drone strikes and the rise to power of Shiite rebels who have taken over the capital and other parts of the country, tribal leaders and Yemeni officials warn.

The militants’ rise comes after months of being squeezed by multiple challenges. Early last year, U.S. drone strikes followed by Yemeni ground troops helped Yemen destroy a key al Qaeda base in the remote mountains of the impoverished, unstable nation. The past year, al Qaeda has also faced fierce competition from the Middle East’s new militant powerhouse, the Islamic State group, which has sought to make inroads into Yemen.

But the expansion of the Shiite rebels known as Houthis has been a godsend for al Qaeda in the Arabian Peninsula, as the branch of the terror network in Yemen is called. The turmoil in Yemen has taken on a sharply sectarian tone, pitting Sunnis against Shiites, to the benefit of Sunni al Qaeda. And while the group has lost some prominent figures in drone strikes over past years, deaths of members of prominent tribes in the strikes have pushed tribesmen toward the militants. […]