Iraqi security forces prepare to attack Islamic State extremist positions as smoke rises from central Tikrit during clashes in the city, 130 kilometers (80 miles) north of Baghdad, Iraq, Friday, March 27, 2015. On the ground, the Iraqi troops pressed their push in Tikrit on Friday as fighter planes pounded IS targets from above. Militants holed up in the center of Tikrit fired mortars at the military, slowing its progress despite the new aerial campaign. (AP Photo/Khalid Mohammed), APTOPIX