Venezuelan President Nicolas Maduro is welcomed by Saudi Crown Prince Salman in Riyadh on Sunday. The meeting was part of Maduro's diplomatic tour of OPEC members to discuss falling oil prices, which have hit Venezuela's economy hard. Reuters /Landov hide caption

itoggle caption Reuters /Landov

King Abdullah (right) and Crown Prince Salman (left) are shown in this 2012 poster. The king, who is at least 90, was hospitalized last week and Salman on Tuesday stepped in for the monarch and delivered an annual televised speech to the nation. FAYEZ NURELDINE/AFP/Getty Images hide caption

itoggle caption FAYEZ NURELDINE/AFP/Getty Images

A Saudi woman poses in this picture to illustrate driving a car in Jiddah as part of a June 2011 protest. An advisory council recently recommended for the first time lifting a ban on female drivers. Susan Baaghil/Reuters/Landov hide caption

itoggle caption Susan Baaghil/Reuters/Landov

Saudi Arabian women wear their traditional face covering, the niqab, at a coffee and chocolate exhibition in the capital Riyadh on Monday. A prominent religious figure said on Twitter that the face veil is not mandatory, sparking a heated national debate. Fayez Nureldine/AFP/Getty Images hide caption

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A member of the Saudi border guards mans a machine gun at the border with Iraq in July. Since the so-called Islamic State launched its offensive this summer in Iraq, Saudi Arabia has sent thousands of troops to the region. Faisal Nasser/Reuters/Landov hide caption

itoggle caption Faisal Nasser/Reuters/Landov

A Saudi woman poses in this picture to illustrate driving a car in Jiddah as part of a June 2011 protest. An advisory council has recommended for the first time lifting a ban on female drivers. Susan Baaghil/Reuters/Landov hide caption

itoggle caption Susan Baaghil/Reuters/Landov

U.S. Secretary of State John Kerry speaks with Saudi King Abdullah bin Abdul Aziz al-Saud as the Saudi ambassador to the United States, Adel al-Jubeir, listens before a meeting at the Royal Palace in Jiddah, Saudi Arabia, on Sept. 11. Brendan Smialowski/AFP/Getty Images hide caption

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An A-18C Hornet attached to Strike Fighter Squadron (VFA) 87, prepares to launch from the flight deck of the aircraft carrier USS George H.W. Bush (CVN 77) to conduct strike missions against Islamic State group targets. Robert Burck/AP hide caption

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A photo released by the U.S. Navy shows the guided-missile cruiser USS Philippine Sea launching a Tomahawk cruise missile against Islamic State targets in Syria on Tuesday. Eric Garst/U.S. Navy/EPA/Landov hide caption

itoggle caption Eric Garst/U.S. Navy/EPA/Landov

The Four Seasons George V hotel is seen in Paris. Armed robbers held up a convoy of Saudi diplomatic vehicles that was bound for a Paris airport from the hotel, with about $335,000 in cash. Iam Langsdon/EPA /LANDOV hide caption

itoggle caption Iam Langsdon/EPA /LANDOV

Fearful of catching the MERS virus, workers wear masks during a soccer match on April 22 at King Fahad stadium in Riyadh. Fayez Nureldine/AFP/Getty Images hide caption

itoggle caption Fayez Nureldine/AFP/Getty Images

A Leopard 2 A6 tank is in operation during the German army exercise in Bergen, Germany, on Oct. 2. Germany said it would sell 270 of the tanks to Saudi Arabia last year. According to official figures, the Saudis were the top buyers of arms from Germany. Peter Steffen /DPA /LANDOV hide caption

itoggle caption Peter Steffen /DPA /LANDOV