Shiite rebels, known as Houthis, chant slogans during a demonstration against an arms embargo imposed by the U.N. Security Council on Houthi leaders, in Sanaa, Yemen, April 16, 2015. (Associated Press) ** FILE **
U.N. Special Envoy for Refugees and Hollywood star Angelina Jolie, right, and U.N. High Commissioner for Refugees António Guterres, left, brief the U.N. Security Council on Syria's refugee crisis, Friday, April 24, 2015. (AP Photo/Bebeto Matthews)
President Obama will be the eco-president when he addresses the U.N. climate summit, but he will reprise his commander role 24 hours later when he gives an address before the U.N. Security Council. (Associated Press)