Citizen soldiers of the Army National Guard (search), which has suffered increasing casualties in Iraq in recent months, will assume a notably more prominent role in the next rotation of U.S. combat forces into Iraq beginning late this year, officials said Thursday.

The number of National Guard brigades in Iraq will grow from three to five, and for the first time in Iraq a National Guard division headquarters will command active-duty brigades.

Under the command of the 42nd Infantry Division of the New York Army National Guard will be two brigades of the active duty 3rd Infantry Division as well as the 256th Infantry Brigade of the Louisiana National Guard.

Overall, National Guard and Reserve forces will make up 42 percent or 43 percent of the total force in Iraq, the director of operations for the Joint Staff, Lt. Gen. Norton Schwartz, told Congress on Wednesday. That compares with a 39 percent share presently and 25 percent last year, he said.

The National Guard has been increasing its numbers in Iraq mainly because the active-duty Army is not large enough to fulfill the requirements, which expanded as the insurgency grew.

Last month, exactly half of the U.S. military deaths in Iraq — 21 of 42 — were members of the National Guard or Reserve. In May, the breakdown was 22 out of 80 deaths, and in April it was 17 of 136.

There are a total of about 140,000 U.S. forces now in Iraq, and about 130,000 are scheduled for the next rotation, Schwartz said.

Some active-duty units scheduled to rotate into Iraq over the coming few months have already served there. They include the 3rd Infantry Division, which helped spearhead the March 2003 invasion and then returned to its bases in Georgia last summer, and the 3rd Armored Cavalry Regiment, from Fort Carson (search), Colo., which is scheduled to go back in February.

The National Guard units scheduled to go are:

— 256th Infantry Brigade, Louisiana.

— 155th Armored Brigade, Mississippi.

— 116th Cavalry Brigade, Idaho, which currently is training at Fort Bliss, Texas.

— 278th Armored Cavalry Regiment, Tennessee, which is scheduled to enter Iraq in November.

— 29th Infantry Brigade, Hawaii.

— Headquarters, 42nd Infantry Division, New York.

All are expected to serve one-year tours in Iraq.