Here’s a back story of what happened when one of the Sunni insurgent leaders turned on al-Qaeda in May:

He hailed the car carrying the feared leader of Al Qaeda in the neighborhood, a man known as the White Lion, on one of Amariyah’s main streets. “We want you to stop destroying our neighborhood,” he told the man.
“Do you know who you are talking to?” said the White Lion, getting out of his car. “I am Al Qaeda. I will destroy even your own houses!”
He pulled out his pistol and shot at Abul Abed. The gun jammed. He reloaded and fired again. Again, the gun jammed.
By this time, Abul Abed said, he had pulled his own gun. He fired once, killing the White Lion.
“I walked over to him, stepped on his hand and took his gun,” Abul Abed, which is a nom de guerre, said at his new, pink-painted headquarters in a renovated school in Amariyah, as an American Army captain seated in the corner nodded his head in affirmation of the account. “And then the fight started.”
It was the beginning of the end for Al Qaeda in Amariyah. The next day, a firefight erupted. Al Qaeda fighters closed in on Abul Abed. Most of the 150 men who had joined him fled. Holed up in a mosque with fewer than a dozen supporters, Abul Abed thought the end was near.
“The blue carpet was soaked red with blood,” he recalled. Then the imam of the mosque called in American help.
A friendship was born.
[…]
‘Americans are our protectors’
Abul Abed said the Sunni revolution has gone too far for that.
“Americans are our protectors and saviors,” he said.
The real enemy of Iraq, he says, now is Iran. He pulled out his mobile phone to show pictures he has saved of the bodies of his four brothers, who were kidnapped and murdered in 2005 by what he suspects was a Shiite death squad with ties to Iran. One of them had a nail driven into his head. Another was missing a hand.
“Even animals wouldn’t do that,” he said, his face darkening. “Iran is so deeply infiltrated in Iraq, the problem here still cannot be solved. Iran wants to demolish us. If the Americans leave, then you can count Iraq as a second Tehran.”

(via)