Iraqi security forces and Shi'ite fighters gesture from the top of an armoured vehicle as they gather at Udhaim dam, north of Baghdad March 1, 2015. Iraqi soldiers and pro-government Shi'ite militias have been massing in preparation for an attack on Islamic State strongholds along the Tigris River to the north and south of Tikrit, hometown of executed former president Saddam Hussein. REUTERS/Thaier Al-Sudani (IRAQ - Tags: POLITICS CIVIL UNREST)