The policy shift, as described by senior U.S. officials, includes targeting fighters whose names aren't known but who are deemed to be high-value terrorism targets or threats to the U.S. The White House stopped short of authorizing attacks on groups of lower-level foot soldiers who are battling the Yemeni government, the officials said.

The U.S. already authorizes drone strikes in Pakistan against those suspected of militant activities but who haven't necessarily been identified by name.

The expansion of the drone campaign in Yemen, to which the administration agreed earlier this month, underlines the difficulty the White House faces in balancing concerns about al Qaeda's apparently growing foothold in southern Yemen against fears that greater CIA and military involvement could propel the U.S. into another regional conflict.

Some military and intelligence officials privately complain that the White House is being too cautious. They argue that more-aggressive U.S. action is necessary to combat the growing threat from al Qaeda in the Arabian Peninsula, or AQAP, and to help the Yemeni government regain control of southern provinces where the group and its allies hold sway.