U.S. fears rapid escalation in the Mideast after Houthis attack Riyadh

Yemen's Houthi armed forces patrol as Yemeni prisoners loyal to the Houthi authorities arrive in the capital Sanaa on September 12 (Mohammed HUWAIS)The United States warned Saturday that hostilities between Saudi Arabia and Iran-backed Houthis could "escalate rapidly" after a missile attack targeted Riyadh for the first time since the Yemen conflict resumed.US President Donald Trump cut short a weekend at Camp David, a secluded presidential complex in rural Maryland, to return unexpectedly to th