The U.S. military map in Iraq in early 2010: Marines are leaving the western desert, Army units are in the former British zone in the south and the overall mission is coalescing around air and logistics hubs in central and northern Iraq.
Meanwhile, commanders will be shifting their attention to helping Iraqi forces take full control of their own security.
The Pentagon has not released the full details of President Barack Obama's plan to end America's combat role in Iraq by Aug. 31 of next year, but the broad contours are taking shape.
Statements from military officials, U.S. government reports and interviews by The Associated Press with Iraqi and U.S. planners offer a wide-angle view of the expected American formation in Iraq when the pullout quickens early next year.
Between 35,000 and 50,000 soldiers are expected to remain in a transition period before all troops must leave by the end of 2011 under a joint pact. In his speech Friday, Obama outlined the roles ahead.
"Training, equipping, and advising Iraqi security forces as long as they remain nonsectarian; conducting targeted counterterrorism missions, and protecting our ongoing civilian and military efforts within Iraq," he said at Camp Lejeune, N.C.
There should be little immediate change in the American presence in 2009.
The bulk of the current 138,000 U.S. troops are expected to remain until Iraq's national elections scheduled for late this year. Maintaining security for the balloting is considered a top priority by the top U.S. commander in Iraq, Gen. Ray Odierno, and other high-ranking Pentagon officials.
Then the pullout will accelerate.
Plans to shift Marines to Afghanistan
The first significant shift could be with the 22,000 Marines in Anbar province, a broad wedge of western desert where insurgents once held sway over key cities such as Fallujah and Ramadi.
The Marines have already tested exit routes through Jordan with plans for a full-scale exodus during the "2010 calendar year," said Terry Moores, deputy assistant chief of staff for logistics for Marine Corps Central Command.
The Marines could possibly leave a small contingent, but expect to turn over military duties to the Army.
The early exit from Anbar carries two important messages.
It's part of Washington's shift of military focus to Afghanistan. Obama plans to send 17,000 more soldiers and Marines to Afghanistan to join 38,000 already fighting a strengthening Taliban-led insurgency.
Anbar also represents a critical turning point of the nearly six-year-old Iraq war. A U.S.-directed effort in late 2006 began to recruit and fund tribal leaders to join the fight against al-Qaida in Iraq and other insurgent groups — which were eventually uprooted in Anbar and began to lose their hold in and around Baghdad.
In the south, the U.S. Army is making plans to fill the void left by the departure this spring of 4,000 British troops based outside Basra, the second-largest city in Iraq and a hub of the nation's southern oil fields.
Odierno has said a division headquarters — about 1,000 personnel — plus an undetermined number of troops would be sent to Basra. The transition is expected to begin in late March, and it's likely a U.S. force will remain around Basra until the final pullout in 2011.
Basra is a proving ground for Iraq's ability to handle security on its own. Iraq launched an offensive last year that — with U.S. help — crippled Shiite militia control in parts of the city. But the small British contingent has largely stayed out of direct security operations, leaving it mostly to Iraqi commanders.
Potential trouble spots in northern Iraq
During a tour of Basra on Friday, British Foreign Secretary David Miliband said some military personnel will remain to train Iraq's navy, but the primary British goal is humanitarian aid and development.
"We will focus upon cultural, economic and educational topics," he told Basra Gov. Mohammed al-Waili.
Northern Iraq, meanwhile, poses the greatest uncertainties for the Pentagon.
Mosul — Iraq's third-biggest city — remains one of the last havens for al-Qaida in Iraq, and its streets are among the most dangerous in the country.
On Tuesday, two Iraqi police opened fire during a U.S. military inspection of an Iraqi security unit in Mosul, killing one American soldier and an interpreter. The attack deepened worries of possible infiltration of security forces in the Mosul area.
U.S. combat support for Iraqis is likely to continue — and perhaps expand — in the coming 18 months. It then could become high on the agenda for the counterterrorism missions, which could include ground forces and aerial surveillance.
U.S. troop strength in the Mosul area is relatively light, but there is a U.S. base on the city's edge.
Obama left open the option for more extensive U.S. military backup if needed.
"There will surely be difficult periods and tactical adjustments," he said. "But our enemies should be left with no doubt: This plan gives our military the forces and the flexibility they need to support our Iraqi partners and to succeed."
The northern city of Kirkuk is another potential trouble spot. Tensions between Kurds and Sunni Arabs over control of the city — and center of the northern oil fields — show no signs of easing.
Training and advising the Iraqi military
Two bases north of Baghdad will likely take more prominent roles next year.
Balad Air Base, home to more than 20,000 U.S. forces, provides air power, logistics and counterterrorism support as well as training for Iraqi security forces. Its location — 50 miles north of Baghdad — offers a rich vantage point for intelligence gathering and analysis across the entire north and specific areas such as the Iranian border.
Another major U.S. air and logistics base in Taji, 12 miles north of Baghdad, sits next to Iraq's new supply and logistics hub.
The two sites would be a natural centerpiece for U.S. training and advising of the Iraqi military, Army Brig. Gen. Steven Salazar, the deputy commanding general at Multi-National Security Transition Command, told the AP recently.
Salazar said the Taji National Supply Depot was designed by the Iraqis to be the "top end" of the supply and logistics chain for its security forces.
In Baghdad, the U.S. military is already making changes in anticipation of the first step of the withdrawal timetable: U.S. forces out of major cities by June.
The United States has handed over the Green Zone to the Iraqi government, closed forward operating bases and combat outposts in the city or turned them into smaller stations where U.S. troops work alongside Iraqi security forces.
But Camp Victory, a huge base on the outskirts of Baghdad in a former Saddam palace complex, will continue to serve as the U.S. nerve center in the capital.
A military official with knowledge of the military planning process told the AP that Camp Victory's proximity to many Iraqi government ministries and the Baghdad International Airport make it a prime location for the U.S. military, and one they are not likely to give up anytime soon.
The base also is expected to expand as it absorbs troops pulling out of Baghdad before the June 30 deadline, said another military official. The officials spoke on condition of anonymity because they were not authorized to release the information.