Washington ? U.S. Army leaders are preparing to announce as early as today a plan to start relieving exhausted troops in Iraq with thousands of soldiers from U.S.-based units and an additional 10,000 National Guardsmen who will be called to active duty.

The deployments will be part of a detailed, two-year plan to make certain that units in Iraq, Afghanistan and other countries where the United States has peacekeeping forces are rotated home after one year.

Military informants told Knight Ridder that Acting Army Chief of Staff Gen. John Keane would designate both active-duty and Army National Guard units to be placed on the list to deploy to Iraq. The informants spoke on the condition of anonymity.

The plan will require the call-up of two specially trained “enhanced brigades” of the Army National Guard for one-year tours in Iraq, in addition to three active-duty brigades also destined for Iraq as replacements. The 1st Cavalry Division at Fort Hood, Texas, will play a key part in Keane’s rotation and assignment plans.

The three active-duty brigades likely to be tapped for Iraq duty this year are a brigade of the 82nd Airborne Division at Fort Bragg, N.C., a new experimental Stryker armored vehicle-equipped brigade of the 2nd Division based at Fort Lewis, Wash., and a brigade of the 1st Armored Division based at Fort Riley, Kan.

There are already more than 200,000 National Guard and reserve troops of all services on active duty out of a total part-time force of 900,000.