Pro-government tribesmen pose as they stand on a mountain where they are positioned to guard their area amid tension with militants of the Shi'ite Houthi group near Amran city, the capital of Amran province, north of the Yemeni capital Sanaa April 12, 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)