Gen. David Petraeus, facing Democratic lawmakers and many voters demanding a quick end to the U.S. engagement in Iraq, suggested the force could fall to about 130,000 by August without jeopardizing modest recent security improvements.
That would return the U.S. troop strength to roughly the same level it was before an increase ordered by President George W. Bush between February and June.
Petraeus said it was not yet possible to predict when the number could go lower.
Petraeus appeared at a congressional hearing seen as a crucial moment in the U.S. debate over the war, which Bush has vowed to pursue but which many Democrats, who control Congress, say must end.
Analysts said Petraeus's recommendation to bring some troops home by Christmas and more in 2008 could provide political cover for Republicans and dissuade them from abandoning Bush while blunting Democratic calls for more dramatic withdrawals.
Both the general and U.S. Ambassador to Iraq Ryan Crocker said they saw some progress in Iraq and defended Bush's decision to boost the troop strength in a war that is now in its fifth year and has killed more than 3,700 U.S. troops and tens of thousands of Iraqis.
I believe we will be able to reduce our forces to pre-surge level by next summer without jeopardizing the security gains, Petraeus said at a joint hearing of the House Armed Services and Foreign Affairs Committees.
The military objectives of the surge are in large measure being met, Petraeus added during a hearing that was repeatedly interrupted by protesters shouting war criminals and other anti-war slogans.
Petraeus said the number of security incidents had dropped in eight of the past 12 weeks and the overall number of civilian deaths from the conflict had fallen by 45 percent since December.
Statistics from other sources suggest a less steep decline and data obtained from Iraqi ministries show 1,773 civilians died in Iraq in August, a rise of nearly 8 percent over February.
Although violence has ebbed in some parts of the country, it continues to rage in others. A suicide truck bomb killed 10 people and wounded 60 in northern Iraq while a car bomb killed two people and wounded six in central Baghdad, police said.
Seven American soldiers were killed in a vehicle accident in Baghdad on Monday and another died from wounds received in a rocket attack on Sunday in northern Kirkuk province, the
military said, bringing U.S. military fatalities to 3,769.
Petraeus said he had proposed that a unit of about 2,200 Marines should leave Iraq this month as previously planned.
If Bush accepts his recommendations, a combat brigade -- which typically has 4,000 soldiers -- would leave in December, followed by four more brigades as well as two Marine battalions of several hundred troops that would depart by August 2008.
Analysts said these withdrawals were largely inevitable.
I don't think the decision to basically 'unsurge' is all that dramatic. All experts were in agreement that the surge was going to die its natural death starting in March, said Colin Kahl of the Center for a New American Security think tank.
The Iraq war began in March 2003 when U.S.-led forces invaded to topple Saddam Hussein. It has dragged on for more than four years amid a vicious insurgency and brutal sectarian warfare between majority Shi'ites and minority Sunnis.
NOT IN THE NATIONAL INTEREST
Bush is expected to give a speech later this week on Iraq but has shown no signs of making drastic troop withdrawals.
While Bush argued the troop increase earlier this year was needed to give Iraqi politicians space to achieve political reconciliation, little such progress is visible at the national level.
Crocker asserted there were signs of political progress in Iraq, particularly at the local level, and said over the long term a secure, stable democratic Iraq at peace with its neighbors is, in my view, attainable.
I am certain that abandoning or drastically curtailing our efforts will bring failure, he said, adding that an Iraq falling into civil war or chaos would cause massive human suffering and could draw in regional players like U.S. antagonist Iran.
The comments by the senior U.S. general and diplomat in Iraq were criticized by leading Democrats.
Clearly, continuing to pursue the president's flawed escalation policy until at least July 2008 is not in the national interest of the United States, said Senate Democratic leader Harry Reid of Nevada.
It is time to change the mission of our troops to one that will promote regional stability and combat terrorism, so that the numbers of our brave men and women in uniform in Iraq can be reduced on a much more aggressive timetable than the one outlined today by General Petraeus, said House Speaker Nancy Pelosi of California.
While many Democratic lawmakers oppose the war, they do not appear to have the votes to cut off funding for it -- the main tool Congress has to force Bush to change strategy.
Some analysts believe that the Democrats, hoping to win the White House in November 2008 elections, fear a major cut in troop levels could both worsen the situation on the ground and open them to political criticism that they lost Iraq.
(Additional reporting by Aseel Kami, Mariam Karouny and Dean Yates in Baghdad, Susan Cornwell, Andrew Gray, Richard Cowan and Paul Eckert in Washington)