FALLUJAH, Iraq — The car bomb in Fallujah exploded in May. On that warm evening, insurgents drove a vehicle packed with explosives into mourners of a slain local tribal leader as they wound through a ramshackle corner of the city, killing 20.

The next day, Fallujah's mayor banned all vehicles from city streets.

If there were no cars, reasoned Mayor Saad Awad Rashid, there could be no car bombs.

"It stopped," said Lt. Col. William Mullen, commander of a shrinking force of U.S. Marines in the city who have watched the insurgency melt into the encircling countryside. "The 'significant events' in the city stopped. I think a lot of (the insurgents) left."

The Americans are not far behind: After surrounding the city with walls and improving security on its streets, Marines are pulling back from the one-time insurgent bastion of Fallujah.

They are redeploying to surrounding areas as the U.S. troop surge allows them to consolidate progress made largely by tribal leaders and local officials in security and civil works.

Among those troops are about 900 Marines with the 3rd Battalion, 3rd Marines from Kane'ohe Bay. The towns the Hawai'i Marines operate in include Zaidon, a few miles southeast of Fallujah, and Karmah, north of the city.

Hawai'i Marines had been on continuous rotations to Haditha, northwest of Baghdad, but the 3rd Battalion, 3rd Marines were shifted to the Fallujah area after they deployed to Iraq in late July.

Karmah is still considered a bastion of insurgent activity, but the new counterinsurgency approach requires striking a balance between aggression and respectful treatment of the Iraqis.

"Going out on patrols, you have to have the mindset that you're going to have (enemy) contact, but you have to treat people with respect," said Lance Cpl. Travis I. Stoner, a 3rd Battalion Marine from San Antonio.

The Marines leave behind in Fallujah a city devastated by years of fighting and starved for reconstruction. Hawai'i Marines with the 1st Battalion, 3rd Marine Regiment, fought door to door in a clearing operation in Fallujah in late 2004.

"We continue to press out from Fallujah to prevent the enemy from getting back in there and having a (return) to the way it was a year ago," said Col. Richard Simcock, who leads Regimental Combat Team-6, the Marine force in and around the city.