Americans urged to leave Middle East country

WASHINGTON -- A pair of suspected U.S. drone strikes killed four al Qaeda militants in Yemen as the United States maintained a heightened security alert in the country and urged all Americans to leave immediately.

Security sources told CNN about the strikes but didn't offer additional details. A Yemeni official said four drone strikes have been carried out in the past 10 days.

None of those killed on Tuesday were among the 25 names on the country's most-wanted list, security officials said.

It is unclear whether the strikes were related to the added security alert in the country after U.S. officials intercepted a message from al Qaeda leader Ayman al-Zawahiri to operatives in Yemen telling them to "do something." The message was sent to Nasir al-Wuhayshi, the leader of al Qaeda in the Arabian Peninsula, the terror group's Yemeni affiliate. U.S. intelligence believes al-Wuhayshi has recently been appointed the overall terror organization's No. 2 leader.

Also Tuesday, the State Department urged Americans in Yemen to leave immediately, citing terrorist activities and civil unrest. All non-emergency U.S. government personnel were also told to leave.

Two U.S. military transport aircraft landed in Yemen on Tuesday to evacuate American citizens.

"In response to a request from the U.S. State Department, early this morning the U.S. Air Force transported personnel out of Sana'a, Yemen, as part of a reduction in emergency personnel," Pentagon press secretary George Little said in a statement.

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