The Pentagon is delaying indefinitely the deployment of an Army combat brigade that was to start heading to Iraq this month as part of a long-planned troop rotation, defense officials said.

The decision — not yet publicly announced — to keep the 3,500 soldiers of the 2nd brigade of the 1st Infantry Division at their home base in Germany may mean a net reduction in the size of the force in Iraq, although that has yet to be determined.

There are now about 132,000 U.S. troops in Iraq.

CountryWatch: Iraq

Top U.S. commanders and officials have said they expect the U.S. military presence in Iraq to shrink over the course of this year. But whether this single move with the 1st Infantry unit would result in an overall reduction is not certain because other decisions about 2006 deployments are pending. Those other decisions hinge on evolving political and military conditions in Iraq.

It remains possible that the brigade from the 1st Infantry eventually will be deployed, according to two defense officials who disclosed the decision to delay the bridge's movement.

The officials spoke on condition of anonymity over the past two days because they were not authorized to discuss the matter until a public announcement is made. That may come as early as this weekend.

If the newly designated leaders of Iraq are unable to complete the formation of a unity government as scheduled this month, or if that process is severely delayed, then U.S. commanders might feel compelled to call on the 1st Infantry brigade in Germany or make other adjustments.

Defense Secretary Donald H. Rumsfeld has said in recent days that he does not expect to receive recommendations from his top commanders about future force adjustments until after the Iraqi government is fully formed.

Other units previously named as part of this year's troop rotation are still on schedule to go to Iraq.

A brigade from the Minnesota Army National Guard's 34th Infantry Division, for example, already is deploying. Other units still on track to go this year include the 3rd brigade of the 82nd Airborne Division, the 3rd brigade of the 2nd Infantry Division and the 3rd brigade of the 25th Infantry Division.

At the time the Pentagon announced this rotation in November, it said the rotation "may be tailored based upon changes in the security situation" and as Iraqi security forces continue to develop the capability to assume fuller responsibilities for securing Iraq.