Gulf monarchs gathered today for an extraordinary summit amid growing international concern over the Saudi-led airstrikes against Shiite rebels in Yemen and a deepening regional threat from the Islamic State of Iraq and al-Sham (ISIS). French President Francois Hollande is the first Western leader to sit in on a summit of the Sunni-dominated Gulf Cooperation Council (GCC). The Riyadh summit brings together leaders from Bahrain, Kuwait, Oman, Qatar, Saudi Arabia and the United Arab Emirates. Yemeni President Abed Rabbo Mansour Hadi also attended the summit as the rebels advance on his southern refuge of Aden.