Iraqi security forces battled Islamic State militants in central Tikrit on Sunday as the United States and its allies provided aerial support and local officials warned that the battle to retake the Sunni Muslim city would not be quick.
"A rapid advance in a city where the ground is littered with bombs and booby-traps is too tough to achieve," said Mayor Osama al-Tikriti.
Islamic State fighters, whose goal is to create a Muslim caliphate across the Middle East, stormed into Tikrit last June during a lightning advance in which they seized swaths of Sunni Iraqi territory before finally being halted outside Baghdad.