Houthi Shiite Yemeni carry coffins of fellow men killed during recent clashes with presidential guard forces, during their funeral procession in Sanaa, Yemen, on Friday. Hani Mohammed/AP hide caption

itoggle caption Hani Mohammed/AP

Shiite Houthi rebels chant slogans after taking over a government military compound in Yemen's capital, Sanaa, in September. The group forced the country's president to resign on Thursday, plunging Yemen into uncertainty. Hani Mohammed/AP hide caption

itoggle caption Hani Mohammed/AP

Female demonstrators hold up posters of Yemen's president during an August pro-government demonstration in Sanaa. The rebels took over the presidential palace on Tuesday. Mohammed Huwais/AFP/Getty Images hide caption

itoggle caption Mohammed Huwais/AFP/Getty Images

Houses of local residents are seen damaged in clashes that erupted between presidential guards and Shiite Houthi fighters in Sanaa, Yemen, on Tuesday. Hani Ali/Xinhua/Landov hide caption

itoggle caption Hani Ali/Xinhua/Landov

South African Pierre Korkie was killed in a failed rescue attempt along with American photojournalist Luke Somers. U.S. officials were reportedly unaware that Korkie was being held along with Somers nor that arrangements had already been made for his release. AP hide caption

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Luke Somers, 33, an American photojournalist who was kidnapped over a year ago by al-Qaida, poses for a picture during a parade marking the second anniversary of the revolution in Sanaa, Yemen. Hani Mohammed/AP hide caption

itoggle caption Hani Mohammed/AP

Yemeni soldiers hold up their weapons at an area seized from al-Qaida in the southeastern province of Shabwa, Yemen, on May 8. President Obama said Wednesday that U.S. strategy against the so-called Islamic State would be similar to how it targeted militants in Yemen and Somalia. Yemen's Defense Ministry/AP hide caption

itoggle caption Yemen's Defense Ministry/AP

Smoke rises from the site of a suicide car bombing at the Defense Ministry in Sanaa, the Yemeni capital, Thursday. Mohammed Huwais/AFP/Getty Images hide caption

itoggle caption Mohammed Huwais/AFP/Getty Images

A Yemeni soldier searches a car near the airport in the capital, Sanaa. The United States has ordered Americans to leave Yemen immediately amid a warning of a possible attack. Mohammed Huwais/AFP/Getty Images hide caption

itoggle caption Mohammed Huwais/AFP/Getty Images

A Yemeni soldier stands guard Tuesday near Sanaa International Airport. Mohammed Huwais /AFP/Getty Images hide caption

itoggle caption Mohammed Huwais /AFP/Getty Images

An army trooper sits beside a machine gun that is mounted on a patrol vehicle at a checkpoint in Sanaa, Yemen. Security is tight in the capital amid warnings about possible terrorist attacks. Khaled Abdullah /Reuters /Landov hide caption

itoggle caption Khaled Abdullah /Reuters /Landov

John Brennan, President Obama's nominee to be the next CIA director, worked closely with Saudi Arabia to set up a secret U.S. drone base there, The New York Times reported. Brennan's confirmation hearing is Thursday. Kevin Dietsch /UPI /Landov hide caption

itoggle caption Kevin Dietsch /UPI /Landov