The CIA did not know in advance that al-Qaeda’s leader in Yemen was among the suspected militants targeted in a lethal drone strike last week, according to U.S. officials who said that the operation went forward under counter­terrorism guidelines that were eased by the Obama administration after the collapse of the U.S.-backed government in Yemen this year.

The officials said that Nasir ­al-Wuhayshi, who also served as ­al-Qaeda’s overall second-in-command, was killed in a “signature strike,” in which the CIA is permitted to fire based on patterns of suspected militant activity even if the agency does not know the identities of those who could be killed.

The disclosure indicates that the CIA continues to employ a controversial targeting method that the administration had signaled in 2013 that it intended to phase out, particularly in Yemen, which U.S. officials have said is subject to more stringent rules on the use of lethal force than in Pakistan.