Tribesmen loyal to the Shi'ite Houthi group chew qat, a mild narcotic, as they take part in a sit-in staged by the group outside Amran city, the capital of Amran province north of the Yemeni capital Sanaa April 9, 2014. Fighters loyal to the Shi'ite tribe, who have repeatedly fought government forces since 2004, are trying to tighten their grip on the north as Yemen moves towards a federal system that gives more power to regional authorities. REUTERS/Khaled Abdullah (YEMEN - Tags: POLITICS CIVIL UNREST RELIGION)