Barack Obama, the US president, has announced he intends to withdraw all US troops from Iraq by 2011.
Speaking in North Carolina, he said on Friday US combat operations would finish by the end of August 2010, with some soldiers staying in other roles to protect US interests.
He said Iraq was "not yet secure" and difficult days lay ahead.
The plan would pull combat troops out of Iraq 19 months after Obama took office in January this year, slightly longer than the 16 months he promised while on the campaign trail in 2008.
Obama said he plans to keep between 35,000 and 50,000 US "support troops" in the country.
Obama announced the new strategy during a trip to the Marine Corps base at Camp Lejeune in the state of North Carolina.
The maintenance of a residual force for a period of time in the country did not come as a surprise, but some in Obama's own party have questioned the size of it.
"When they talk about 50,000, that's a little higher number than I had anticipated," Harry Reid, the senate majority leader, said.
Some Republicans also criticised the announcement, with John Boehner, the House Republican leader, saying that while such proposals may have sounded good during the election campaign "I do think it's important that we listen to those commanders and our diplomats who are there to understand how fragile the situation is."
Officials told AP that national elections in Iraq set tentatively for December could be postponed until 2010, which could be why Obama's timetable for withdrawing
combat troops has also been extended by a few months.
|An existing agreement under Bush said
all forces should leave by 2011 [AFP]
Friday's Iraq announcement came a day after he unveiled an ambitious budget that promises a major overhaul of America's costly healthcare system and sets aside an additional $750bn to help rescue America's troubled financial system.
There are currently about 142,000 US troops stationed in Iraq.
An existing US-Iraq agreement, the Status of Forces Agreement, or Sofa, negotiated under George Bush, the former president, already called for US troops to withdraw from Baghdad and other cities by the end of June this year, with all American forces out of the country by the end of 2011.
More than 4,250 US military members have died since the war began in March 2003, though US military deaths plunged by two-thirds in 2008 from the previous year.
Some analysts have attributed the fall in casualties to improving security after a troop build-up, or so-called surge, in 2007.