WASHINGTON—The U.S. has killed the leader of al Qaeda’s Yemen branch, who was also a deputy to al Qaeda global leader Ayman al-Zawahiri, President Trump said Thursday.

Mr. Trump gave no details about the counterterrorism operation that killed Qasim al-Raymi, emir, or leader, of al Qaeda in the Arabian Peninsula, which U.S. counterterrorism officials count among the terrorist group’s most potent affiliates.

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