BAGHDAD - The U.S. military handed over control of the once brutally violent Anbar province to Iraqi forces Monday, marking a major milestone in America's plan to eventually send its troops home.

But American officials warned that the struggle against al-Qaida in Iraq and other insurgents was not over in the western region that was the scene of some of the bloodiest battles since the 2003 invasion.

"This war is not quite over, but it's being won and primarily by the people of Anbar. Al-Qaida has not been entirely defeated in Anbar, but their end is near and they know it," said Marine Maj. Gen. John Kelly, the top American commander in Anbar, during the handover ceremony.

The return of security control to Iraqi authorities doesn't mean U.S. troops, which number about 25,000 in the region, will leave Anbar, a vast, mostly desert area that extends from the western outskirts of Baghdad to the borders of Syria, Jordan and Saudi Arabia.

But U.S. troops will cut back on security patrols and focus on training Iraq's army and police.

For years Anbar, the 11th of 18 provinces to switch to Iraqi control, was center stage of the Sunni insurgency and scene of some of the bloodiest battles of the war. The Anbar city of Fallujah became the symbol of Sunni resistance until it fell to American troops in November 2004 in the most intense urban combat of the war.

The province was the base of the shadowy al-Qaida in Iraq and its leader, Abu Musab al-Zarqawi who used the area as a staging ground for attacks in Baghdad until he was killed in a 2006 American airstrike.

Just two years ago a Marine intelligence report had concluded that al-Qaida had made such inroads that the war was "lost" there.

But later that year, a backlash was born in Anbar against al-Qaida among Iraq's Sunni Arab community because of the group's attempt to dominate the insurgency. Many Iraqi tribal leaders opposed al-Qaida's brutal tactics, including mass killings of Shiite civilians and Sunni leaders who would not accept the movement's rule.

Disaffected Sunni sheiks organized awakening councils that joined forces with the Americans to push al-Qaida from the province. That enabled U.S. forces to gain control of the provincial capital of Ramadi and other cities long considered killing zones for Americans.

Now Anbar is considered one of the quieter parts of the country, though bitterness between the awakening councils and the central Baghdad government, which is predominantly Shiite, remains and could complicate political reconciliation efforts.

During Monday's ceremony, the head of the local awakening council complained that the central government was not crediting Sunni tribesmen enough for fighting al-Qaida and placing too much attention on their past ties to Saddam Hussein.

The Anbar governor paid tribute to those killed in the fight against al-Qaida, including Abdul-Sattar Abu Risha, the leader of the Sunni awakening councils who was killed in a bombing near his home in 2007.

"This day was accomplished because of the sacrifices of martyrs who gave their blood -- the sons of blessed tribes," Gov. Maamoun Sami Rashid al-Alwani told the crowd of American and Iraqi officials under a tent in the provincial capital of Ramadi.

Monday's ceremony was postponed several times in recent months, with delays blamed on weather and a last-minute disagreement between the governor and the Iraqi government over control of security forces.

But there were also security concerns. As recently as late June, a suicide bomber wearing a police uniform killed more than 20 people, including three Marines and several prominent pro-U.S. tribal leaders, in the town of Karmah, 20 miles west of Baghdad.

Also Monday, a senior aide to Prime Minister Nouri al-Maliki said the Iraqis have submitted a list of proposals to tweak a draft of a U.S.-Iraqi security agreement.

The changes were submitted to the U.S. government in Baghdad, said the aide, who spoke on condition of anonymity because he wasn't allowed to release the information.

U.S. and Iraqi officials have said the two sides agreed tentatively to a schedule that included a broad pullout of American forces by the end of 2011. But al-Maliki's has suggested that his government is still not satisfied with that arrangement.