The Pentagon (search) now says it will include several thousand more Marines than originally planned in the rotation of fresh combat and support forces in Iraq next year.

As a result, the overall force is likely to be larger than the 105,000 total the Pentagon had estimated on Nov. 6, when it first announced most details of the rotation plan, expected to start in January. There are about 130,000 U.S. troops there now.

In the announcement Wednesday, Defense Secretary Donald H. Rumsfeld (search) approved the mobilization of 9,900 Army, 1,290 Navy and 3,208 Air Force reserve personnel for the rotation.

Rumsfeld also put on alert 4,228 Army, 1,290 Navy and 2,381 Air Force reservists, to let them know they may be mobilized for duty in Iraq. The specific units alerted and mobilized Wednesday were not disclosed. The Pentagon says they can expect to be on active duty for up to 18 months.

The rotation is due to be completed in May, and the fresh forces are expected to stay there for one year.

Although the Pentagon did not provide a total, it appears that by May, it will be closer to 110,000, counting the additional Marines (search).

For reasons not explained Wednesday, the Pentagon said it had decided to send an additional three battalions of Marines. Those would be beyond the 20,000 designated on Nov. 6. The initial group of 20,000 is headed by the 1st Marine Division, from Camp Pendleton, Calif.

The Pentagon also did not specify how many Marines would be in the three battalions. Officials said the total, including support and service support troops associated with the combat battalion, had not yet been determined. They estimated it would be in the range of several thousand.

The Pentagon has struggled to set the troop rotation for 2004 because of the Bush administration's inability so far to persuade its international partners to contribute significant numbers of troops.

Turkey had offered to send thousands but balked in the face of Iraqi political opposition. South Korea has offered 3,000 troops, but it has not yet said whether they would be combat troops -- as preferred by the Pentagon -- or support forces to do humanitarian work. Japan also has offered support forces but has not said when they would be made available.

Rumsfeld also approved on Wednesday the mobilization of 2,995 Army, 100 Marine Corps and five Air Force reservists for a rotation of U.S. forces in Afghanistan next spring. That brings to 6,906 the number of National Guard and Reserve personnel who have been mobilized for that rotation. The main active-duty unit in the rotation is the Army's 25th Infantry Division.