The Pentagon has said that it will send some 20,000 troops to Iraq to replace US soldiers in the war-torn country.
The soldiers are from the Army's 3rd Brigade of the 4th Infantry Division, the I Marine Expeditionary Force Headquarters, and two regimental combat teams, Pentagon spokesman Bryan Whitman told reporters on Tuesday.
Except for the Marine headquarters, all the troops will have to begin arriving in Iraq in December, Whitman said.
He did not give a precise date when the headquarters will be deployed, except that it was "into the next year".
The troops are not part of the security "surge" that has brought the current number of troops in Iraq to 159,000, Whitman said.
Instead, "this is part of the normal planning for the normal rotation", he added.
Rather than talking about troop numbers, the Pentagon has been characterising troop strength in Iraq by talking about the number of combat brigades deployed in the region. The typical Army combat brigade has 3,500 troops.
The security "surge" that began in January added an additional five combat brigades, bringing the total to 20 combat brigades.