WASHINGTON (AP) — The Pentagon on Monday announced upcoming deployments of more than 42,000 troops, including 25,000 active duty Army soldiers who would be sent to Iraq beginning in the fall to replace troops scheduled to come home by year’s end.

The deployments would maintain a level of 15 brigades in Iraq, or roughly 140,000 troops ó the number military leaders expect will remain on the warfront at the end of July, once the currently planned withdrawals are finished.

Under the new Pentagon policy effective in August, those active duty Army units will serve for 12 months, rather than the 15-month tours that units in Iraq now are serving. The bulk of the soldiers deploying later this year returned from Iraq late last year, and will have gotten about a year at home to rest and retrain.

As part of the announcement, The Pentagon alerted four National Guard Army brigades, or about 14,000 troops, to begin preparing for deployments to Iraq beginning next spring, and one National Guard Army brigade, with about 3,100 soldiers, to prepare to deploy to Afghanistan in the spring of 2010.

The Guard announcements, said Pentagon spokesman Bryan Whitman, are being made far in advance so that soldiers and their families can begin training and other preparations for their service.

Guard brigades heading to Iraq will provide security, while the brigade scheduled to go to Afghanistan in 2010 would train Afghan national forces.

Gen. David Petraeus, the top U.S. commander in Iraq, has said the U.S. will complete the withdrawal of the 20,000 troops that were sent to Iraq last year to tamp down the escalating violence in Baghdad. At the peak, there were 20 brigades with more than 170,000 U.S. troops in Iraq.

Beyond that, he said he wants 45 days to evaluate the security conditions in Iraq, after which he will begin to decide whether more troops can be pulled out. The plan leaves open the possibility that the U.S. could keep 15 brigades there through the end of the years ó as voters go to the polls and elect a new president.

Currently there are 155,000 troops, including 17 combat brigades, in Iraq.

The seven Army combat brigades and one division headquarters units that would be sent to Iraq later this year are:

ó 25th Infantry Division Headquarters

ó 2nd Brigade, 4th Infantry Division, from Fort Carson, Colo.

ó 3rd Brigade, 25th Infantry Division, from Schofield Barracks, Hawaii

ó 2nd Brigade, 1st Infantry Division, from Fort Riley, Kan.

ó 3rd Brigade, 82nd Airborne Division, from Fort Bragg, N.C.

ó 172nd Infantry Brigade from Schweinfurt, Germany

ó 3rd Brigade, 1st Cavalry Division, from Fort Hood, Texas.

ó 1st Brigade Combat Team, 25th Infantry Division, from Fort Wainwright, Alaska.

The four National Guard brigades being alerted for Iraq duty are:

ó 72nd Brigade Combat Team, Texas National Guard

ó 2nd Brigade Combat Team, 28th Infantry Division, Pennsylvania National Guard

ó 256th Brigade Combat Team, Louisiana National Guard

ó 278th Brigade Combat Team, Tennessee National Guard

The unit told to prepare for deployment to Afghanistan was the 86th Brigade Combat Team from the Vermont National Guard. There are currently 33,000 U.S. troops in Afghanistan, including 15,000 serving with the NATO-led International Security Assistance Force, and 18,000 in the U.S.-led effort to train the Afghan Army and conduct counterinsurgency operations.