WASHINGTON - Army brigades from Texas, New York and Pennsylvania, and two Marine units from North Carolina have been ordered to deploy to Iraq early next year, the Pentagon announced Monday.

The units - which include about 33,000 troops - would replace forces already in Iraq, and allow the U.S. to maintain 15 combat brigades in the country through 2009 if needed.

The units are:

n1st Brigade, 1st Cavalry Division, Fort Hood

n2nd Brigade, 1st Cavalry Division, Fort Hood

n3rd Brigade, 10th Mountain Division, Fort Drum, N.Y.

n56th Stryker Brigade, 28th Infantry Division, Pennsylvania National Guard

n6th Regimental Combat Team, Camp Lejeune, N.C.

n8th Regimental Combat Team, Camp Lejeune, N.C.

The deployment decisions could change depending on whether Gen. David Petraeus, the top U.S. commander in Iraq, decides in the fall to further reduce troop levels in Iraq.

If he decides fewer brigades will be needed in Iraq during the next year, there is the chance units could simply be directed to the war in Afghanistan instead. Military leaders have said they want to send more troops to Afghanistan because of the increase in violence there.