The transfer of security responsibilities to Iraqi forces means U.S. troops moving into a support and advisory role, Bush said in a statement released by the White House.

"Not long ago, Anbar was one of the most dangerous provinces in Iraq," Bush said. "Al-Qaida was in control of almost every major population center ... ."

Anbar is the 11th of Iraq's 18 provinces to be transferred to Iraqi security responsibility.

"Anbar is no longer lost to al-Qaida," Bush said. "It is al-Qaida that lost Anbar."

More than 25,000 U.S. troops serve in Anbar, a region west of Baghdad. They will remain there and shift their mission to supporting Iraqi forces.

U.S. Ambassador to Iraq Ryan Crocker and U.S. Army Gen. David Petraeus, commanding general of the Multinational Force in Iraq, said in a statement the transition an important step.

"The provincial and military leadership in Anbar will have to work cooperatively in order to attain the sustainable security necessary for long term economic prosperity," Crocker and Petraeus said.