Sunni fighter Abu Mujahid lost a leg battling U.S. Marines in the Iraqi city of Falluja, scene of some of the fiercest battles of the Iraq war. Small pieces of shrapnel still pit his skull and scars decorate his body after a missile strike in 2004 by a U.S. warplane on the city in the western province of Anbar -- Iraq's Sunni heartland and once a stomping ground for al Qaeda.. "Yes, we fought them to the death and we dreamed of the day when they would leave Iraq," he said, laying aside a crutch as he sat down on a plastic chair in his house. "But their withdrawal at this time is not in Iraq's interest," Abu Mujahid said. His views echo widespread fears for the future among once dominant Sunnis, many of whom joined the insurgency after the 2003 U.S.-led invasion but now fear the departure of U.S. forces will cement Shi'ite Muslim -- and Iranian -- domination. U.S. forces will not leave Iraq for another 16 months, the deadline for a complete withdrawal set in a bilateral security pact signed by former President George W. Bush in 2008. But the U.S. military formally ends combat operations and limits it numbers to 50,000 on August 31, down from a peak of around 170,000 three years ago when the sectarian warfare unleashed after the invasion reached a frightening peak. The remaining U.S. troops in Iraq will focus on advising and assisting their Iraqi counterparts, playing a back-seat yet still significant role in the continuing fight against an al Qaeda-led Sunni Islamist insurgency and Shi'ite militia. Many Iraqis have mixed feelings about the gradual U.S. withdrawal. Any initial jubilation over the fall of Saddam Hussein and his suppressive Baath party regime quickly turned to horror when sectarian war ignited and spread. Tens of thousands were killed and Iraq 7-1/2 years on is a rubble-strewn and dusty wreck, where public electricity only lasts a few hours per day, government bureaucracy is an opaque and corruption-riddled maze and jobs are painfully scarce.