The U.S. military command in Iraq said Tuesday it intends to complete the withdrawal of the Army's 3rd Infantry Division (search) by September, but officials said they could make no hard promises because of the unsettled state of security in Baghdad (search) and elsewhere in Iraq.

The timetable for the 3rd Infantry's return is particularly sensitive because the soldiers and their families had been led to believe the troops would return home once major fighting in Baghdad was over. They, along with the Marines, led the charge that toppled Baghdad on April 9.

There has been no announced timetable for the 1st Marine Expeditionary Force (search) to return home.

The vast majority of the Air Force and Navy units that fought in the war left the area weeks ago.

The Pentagon is hard pressed to find ground force replacements, either American or foreign, and the top commander in Iraq, Gen. John Abizaid, says it is important to maintain the current level of troops, which include about 147,000 Americans and about 13,000 from Britain and other countries.

Last week, Defense Secretary Donald H. Rumsfeld laid out for Congress a specific timetable for the 3rd Infantry's return. One brigade would come home in July, another in August and the third in September, he said.

But on Monday that was thrown in doubt. The 3rd Infantry's headquarters at Fort Steward, Ga., announced that those pegged for an August and September return "will remain in Iraq to maintain the current force level." It did not say how long they would remain, but the news dashed hopes of family members who had been told just a week earlier to expect a full return by September.

It was not the first time the families have been disappointed since the fall of Baghdad. On May 29 the 3rd Infantry informed families that soldiers' return home had been delayed because Pentagon officials deemed it necessary to keep a larger force than anticipated "for a period of time."

On July 7, two days before Rumsfeld reported to Congress, Fort Stewart announced in a news release that in addition to the return this month of the division's 3rd Brigade, the rest of the division could be expected back by August. The news release was removed Tuesday from the 3rd Infantry's Web site.

On Sunday, Maj. Gen. Buford C. Blount III, the 3rd Infantry's commander in Iraq, wrote in an e-mail message to family members that he had "disappointing news." A decision was made "at the highest levels," he said, to maintain the current force levels "due to the uncertainty of the situation in Iraq and the recent increase in attacks on the coalition forces."

"That means that part of 3ID (3rd Infantry Division) will be staying here for a while longer. I wish I could tell you how long that is, but everything I have told you before has changed."

The only thing that has not changed, Blount and Pentagon officials said Tuesday, is that the 3rd Brigade of the 3rd Infantry will continue its redeployment to Fort Benning, Ga., this month, as planned.

As for the other two brigades, totaling about 9,000 soldiers, Rumsfeld spokesman Lawrence Di Rita said they would be out of Iraq by fall and possibly by September. Di Rita described that as a "notional timeline" subject to change.

"This is going to be a moving target in terms of timing until the full redeployment plan is established," he said.

Asked to explain why Rumsfeld's description of the timetable last week had been put in doubt, Di Rita said it remained possible that it would unfold as the defense secretary stated. On the other hand, Di Rita said details of the redeployment plan were still being discussed.

Rumsfeld's testimony was based on "the best information he had available at the time," Di Rita said. "Last week the thinking was that we might do it in this orderly sequence. Now the thinking may be different."