Earlier this month, Mohammed bin Salman, Saudi Arabia's new deputy crown prince, met with Egyptian President Abdel Fattah el-Sissi in Cairo. Egyptian Presidency Handout/EPA /Landov hide caption

itoggle caption Egyptian Presidency Handout/EPA /Landov

Saudi King Salman (center) appears alongside then-Crown Prince Muqrin bin Abdulaziz (third from left) and then-deputy Crown Prince and Interior Minister Mohammed bin Nayef (left) in January. Muqrin has since been pushed aside to make way for Mohammed. Saul Loeb/AFP/Getty Images hide caption

itoggle caption Saul Loeb/AFP/Getty Images

Supporters of the Shiite Houthi movement brandish weapons as they take part in a demonstration in Yemen's capital of Sanaa on Thursday, protesting the Saudi-led military "Decisive Storm" air campaign. Mohammed Huwais/AFP/Getty Images hide caption

itoggle caption Mohammed Huwais/AFP/Getty Images

Saudi Arabia's army fires artillery shells toward Houthi rebels along the Saudi border with Yemen on April 15. Outside Saudi Arabia, many are critical of the military campaign and question whether it will succeed, but it is popular inside the kingdom. STR /Reuters/Landov hide caption

itoggle caption STR /Reuters/Landov

Dr. Awad Al-Yami, an art therapist trained at the University of Pennsylvania, is a counselor at a Saudi Arabian center that seeks to rehabilitate convicted terrorists. The center claims a success rate of more than 80 percent, but acknowledges that some return to extremist groups like al-Qaida. Deborah Amos/NPR hide caption

itoggle caption Deborah Amos/NPR

Houthi fighters gather in the Yemeni city of Aden on Thursday. The Shiite rebels and their allies seized the presidential palace in this southern coastal city. Wael Qubady/AP hide caption

itoggle caption Wael Qubady/AP

Pakistani activists march in support of the Saudi government at a protest in Quetta on March 30, 2015. Pakistan is the latest country to join a Saudi-led coalition fighting Houthi rebels in Yemen. BANARAS KHAN/AFP/Getty Images hide caption

itoggle caption BANARAS KHAN/AFP/Getty Images

Secretary-general of the League of Arab States Nabil Elaraby (left) and Egyptian Foreign Minister Sameh Shukri attend a news conference after the closing session of the Arab League Summit in Sharm el-Sheikh, Egypt, on Sunday. The 22-nation body agreed in principle to establishing a regional security force. Cui Xinyu/Xinhua/Landov hide caption

itoggle caption Cui Xinyu/Xinhua/Landov

Yemenis walk past near oil tankers that were burnt during clashes between Shiite Houthi rebels and their opponents in the capital, Sanaa, in September. Saudi Arabia launched airstrikes this week to counter the Houthis' offensive. Mohammed Huwais/AFP/Getty Images hide caption

itoggle caption Mohammed Huwais/AFP/Getty Images

A Houthi Shiite fighter stands guard Thursday as people search for survivors under the rubble of houses destroyed by Saudi airstrikes near Sanaa Airport in Yemen. Hani Mohammed/AP hide caption

itoggle caption Hani Mohammed/AP