Baghdad: A security pact that sets a timetable for troops to leave Iraq requires a shift in how the US carries out combat missions during its remaining time in the country, the top US military commander in Iraq said on Friday.

General Ray Odierno said in a written statement to troops that they would be receiving new rules of engagement.

The security pact, "though, will require a subtle shift in how we plan, coordinate and execute combat missions throughout Iraq," Odierno said.

He said that under the new terms of agreement, US troops will coordinate and execute all operations with the approval of the Iraqi government and implement them through the Iraqi security forces.

Odierno released the statement a day after Iraq's three-member presidential council signed off on the pact, which requires US troops to leave Iraq by January 1, 2012.

It also requires American soldiers withdraw from Iraqi cities by the end of June 2009.

Under the agreement, Iraq will gain strict oversight over the nearly 150,000 American troops now on the ground, representing a step toward full sovereignty for Iraq.

Odierno also said US troop would continue to conduct operations in Iraq against Al Qaida and other extremist groups.

"But we must do so with respect for the Iraqi Constitution and laws, and we must continue to treat all Iraqi citizens with the utmost dignity and honour," he wrote.