U.S. Marines began joint patrols with Iraqi security forces Monday in the city of Fallujah (search) under the agreement that ended the almost monthlong siege of the city.

Marines in Humvees and armored vehicles entered the Sunni Muslim (search) city west of Baghdad in a convoy with Iraqi security forces in pickup trucks.

The first Iraqi pickup truck flew the red, white and black Iraqi flag, which the Iraqi Governing Council (search) has proposed changing to the outrage of many Iraqis.

"It is a good day for peace in Fallujah," said Marine Maj. Gen. James N. Mattis, after meeting with local leaders. "Nobody shoots, everybody waves and smiles. Any day that there is no shooting it is good."

Marines began the siege of Fallujah on April 5 after the killing and mutilation of four U.S. civilian contractors.

Ten Marines and several hundred Iraqis were killed before the siege was lifted in an agreement providing for the Americans to pull back and transfer primary security responsibility to an Iraqi force led by officers from Saddam Hussein's military.

The Fallujah brigade is expected to number some 1,500 fighters, many of them soldiers from the old Iraqi army who live in the area. U.S. officials acknowledged some may have fought the Marines in the Fallujah siege.