Washington  - US Secretary of State Condoleezza Rice and Defence Secretary Robert Gates briefed lawmakers Wednesday on the pending troop agreement with Iraq.

The agreement establishes the legal basis for the future presence of US troops in Iraq, after a UN mandate expires December 31, and calls for the withdrawal of all forces by the end of 2011.

"The security situation has improved so dramatically, and the Iraqi security forces have improved so dramatically that we are confident that if things continue to trend as they have been, our services will not be needed in Iraq come 2012," Pentagon spokesman Geoff Morrell told reporters.

There are about 150,000 soldiers in Iraq, who could begin winding down operations at the end of this year if the deal, known as a Status of Forces Agreement (SOFA), has not been completed. Alternatively, the United States and Iraq could seek an extension of the UN mandate.

Washington and Baghdad on Monday signed the SOFA, which still requires the approval of Iraq's fractious Parliament. Some Iraqi lawmakers loyal to radical Shiite cleric Moqtada al-Sadr oppose the deal.

The US Congress does not need to vote on the measure.

Under the deal, US troops would abandon outposts in Iraqi cities in 2009. The timeframe for withdrawing US forces by 2011 mirrors US president-elect Barack Obama's pledge to pull US combat forces out of Iraq within 16 months of taking office in January. (dpa)