Fallujah, Iraq ? U.S. Marines began withdrawing from this volatile city Friday, taking up positions a few miles away as commanders began to hand over responsibility for pursuing insurgents to a new Iraqi brigade led by former officers who served in Saddam Hussein’s military.

The exit of some Marine units from Fallujah and the embrace of former Iraqi generals reflected a major strategy shift for the U.S. military as it attempts to retake the city from well-armed fighters. The top Marine commander in Iraq has chosen to assemble what amounts to a Sunni Muslim militia run by officers once blacklisted by U.S. occupation forces in an attempt to avoid a new offensive that could be politically damaging to the United States in Iraq and across the Arab world.

Leader of the Fallujah Protective Army, Maj. Gen. Jassim Mohammed Saleh, strides past a U.S. Army checkpoint Friday on the edge of Fallujah, Iraq. Saleh, a veteran of Saddam's Republican Guard, will lead a 1,100-member Iraqi force that has begun taking over Marine positions in Fallujah.

The general who will lead Iraqi troops in Fallujah — Jassim Mohammed Saleh, 49, the former commander of a brigade of Saddam’s elite Republican Guard — made a triumphant entry into the city on Friday.

But the plan drew condemnation from many quarters of Iraq’s fractious population and appeared to raise tensions between majority Shiites and the Sunni minority that dominated Saddam’s government. Even as the transition unfolded, a car-bomb attack killed two Marines and wounded six at a base outside Fallujah.

After initial confusion among senior U.S. officials about the new arrangement, the Marine command in Iraq issued a statement saying that the new Fallujah Brigade would “assume responsibility for security and stability” by manning checkpoints and other positions in the city of 200,000.

The U.S. military’s chief spokesman in Iraq, Brig. Gen. Mark Kimmitt, insisted at a news conference in Baghdad that Marines were not withdrawing from the city and that the new Iraqi force would be “completely integrated” with U.S. forces. But in Fallujah, Marines were observed traveling out of the city for much of the day in convoys.

As of Friday, 732 U.S. service members have died since the beginning of military operations in Iraq, according to the Department of Defense.