The US is to withdraw about 15,000 troops from Iraq from next month, the deputy defence secretary has announced.
US troops are training Iraqi forces
Paul Wolfowitz told a senate committee the troops were those whose tour of duty was extended last month to bolster security for the 30 January election.
But Mr Wolfowitz said Iraq had a "very difficult road ahead" and the US would keep 135,000 troops there during 2005.
The high turnout and limited violence during Sunday's election may have prompted the move, correspondents say.
But violence has flared up again and two US marines were killed on Wednesday in al-Anbar province, the US military said on Friday.
Speaking before the Senate Armed Services Committee, Mr Wolfowitz repeated that the US administration would set no timetable for American forces to withdraw from Iraq.
"I think we'll be able to come down to the level that was projected before this election," he said.
Mr Wolfowitz said the US military was training Iraqi security forces, but this had encountered "countless challenges and suffered numerous setbacks" and much work "clearly needs to be done".
"But what we don't want to do is prematurely hand over an area and then create a place where the enemy can organise and operate," he said.
"I think you can see over the last couple years there have been a couple such mistake. We don't want to repeat them."
Mr Wolfowitz said it was "a worthwhile trade-off," to keep US forces deployed in Iraq longer if that led to capable Iraqi security forces being fielded faster.