Iraqi security forces and Shiite fighters from the Popular Mobilisation units gather next to a mural depicting the emblem of the Islamic State (IS) group outside one of the presidential palaces in Tikrit, on April 1, 2015, a day after the prime minister declared victory in the weeks-long battle to retake the city from the IS group. Iraqi forces battled the last jihadists the northern city on April 1, 2015 to seal a victory the government described as a milestone in efforts to rid the country of the Islamic State group. AFP PHOTO / AHMAD AL-RUBAYE (Photo credit should read AHMAD AL-RUBAYE/AFP/Getty Images)

Iraqi security forces and Shiite fighters from the Popular Mobilisation units gather next to a mural depicting the emblem of the Islamic State (IS) group outside one of the presidential palaces in Tikrit, on April 1, 2015, a day after the prime minister declared victory in the weeks-long battle to retake the city from the IS group. Iraqi forces battled the last jihadists the northern city on April 1, 2015 to seal a victory the government described as a milestone in efforts to rid the country of the Islamic State group. AFP PHOTO / AHMAD AL-RUBAYE        (Photo credit should read AHMAD AL-RUBAYE/AFP/Getty Images)