Saudi Arabia and its Arab allies have been bombing Yemen relentlessly with critical American support for three months now—yet this air campaign has had little effect on their foes, the Iranian-backed Houthis who still control most of the country. The Arab coalition is facing the same dilemma as the United States in Iraq and Syria: what to do when overwhelming air power fails to achieve political objectives because of an acute deficit of local support to change the balance of power on the ground.