Tribesmen loyal to the Shi'ite Houthi group walk in a protest camp where the group is staging an anti-government sit-in 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)