The Middle East today is defined by an Arab world steeped in the anarchy of dissolving secular states and proliferating Islamist armed non-state actors. These entities consist of different Muslim sects, the largest of which is composed of Sunnis. Amid the diverging interests, Saudi Arabia and the Islamic State are the main contenders for Sunni Arab leadership. Meanwhile, the three non-Arab powers – Turkey, Iran and Israel – are trying to manage the regional commotion according to their national interests. From a distance, the United States want...