WASHINGTON (AP) -- The military surge into Iraq that began more than 18 months ago has ended. But 150,000 U.S. troops remain, as many as 15,000 more than before the buildup began.
In recent days, the 3rd Infantry Division's 2nd Brigade, the last of the five additional combat brigades sent in by President Bush last year, left the country.
Its departure marks the end of what the Pentagon calls the "surge." And it starts the 45-day evaluation period that Gen. David Petraeus, the top U.S. commander in Iraq, told Congress he would need to assess the security situation and determine how many more troops he could send home.
In the complex battlefield that is Iraq, it's not that easy.
While there now are technically 13 Army and two Marine combat brigades in Iraq - the same as before the buildup - the force is as much as 10 percent larger than it was in January 2007.
Military officials contend comparisons are not valid because a chunk of the remaining troop bulge is due to units that are overlapping, as two brigades begin moving out of Iraq, while their two replacements move in. The overlap could add up to 6,000 soldiers.
Also, one of the units moving out, the 1st Brigade, 82nd Airborne Division, is much smaller than the one taking its place - the 4th Brigade, 1st Cavalry Division.
So, the officials suggested, the military buildup may not really be over until the transitions are complete.
The key cause for the larger force is the change in mission in Iraq, as the U.S. military is using more trainers, security and support troops to back up the growing Iraqi force. Also, the U.S. units there now are bigger, and they are bolstered by more support forces.
When the military buildup began, there were between 132,000 and 135,000 troops in Iraq. Over time, however, the Pentagon poured troops into Baghdad and the belt of communities that surround it, including the volatile areas of Basra and Sadr City.
With more troops, the military needed more support, including military police to guard detainees and National Guard units to provide security for bases, convoys and other operations.
Earlier this year, military leaders acknowledged that the force in Iraq when the buildup ended would be larger than before it began. And they suggested that the post-buildup force would total about 142,000.
Commanders also have talked carefully, but somewhat optimistically, about the prospects for cutting troop levels more later this fall.
In recent months, they have pointed to two significant improvements: Violence is down, and the Iraqi forces are rapidly growing in size and ability.
Last week, Maj. Gen. Michael Oates, commander of the 10th Mountain Division, told Pentagon reporters that the security situation in his area south of Baghdad "is probably the best we've ever seen it."
Oates would not predict any troop cuts, and other military leaders have been reluctant to talk specifics.
Adm. Mike Mullen, chairman of the Joint Chiefs of Staff, has suggested that if security continues to improve in Iraq, the Pentagon may be able to send some units to Afghanistan instead of Baghdad as scheduled early next year. But he has also stressed that he will wait for Petraeus to make his assessment.
For his part, Petraeus remains mum. When questioned by lawmakers in May, he would say only that he is likely to recommend more troop cuts in the fall.
"I do believe there will be certain assets that, as we are already looking at the picture right now, we'll be able to recommend can be either redeployed or not deployed to the theater in the fall," he said.
Asked last week about future troop reductions, Defense Secretary Robert Gates said that as the Iraqi security forces get stronger and better, "we will be able to continue drawing down our troops." He added that the transition of control to the Iraqis is well under way, and "based on everything that I'm hearing will be able to continue."
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