President Bush has ordered a suspension of U.S. troop withdrawals from Iraq after July and shortened tours for incoming troops.

In a major speech on the war at the White House Thursday, Mr. Bush defended his war policy, saying it has reduced sectarian violence and civilian and military deaths.

He said thanks to a surge in U.S. troops 15 months ago, U.S. and Iraqi forces have the initiative in the war and the prospect of success has been revived.

But Mr. Bush acknowledged complications remain, including al-Qaida and Iranian-backed fighters.

He is accepting the recommendations of his top U.S. commander in Iraq, General David Petraeus on the war.

The general says U.S. troop withdrawals should be suspended starting in July to allow time for commanders to evaluate security conditions.

That is expected to leave about 140,000 troops on the ground in Iraq after a new U.S. president is elected in November.

Mr. Bush also called for shortened tours for U.S. troops sent to Iraq, starting in August. Soldiers would serve 12 months instead of 15 to ease the military strain of extended deployments.

Troops sent to Iraq before August would still have to carry out their 15-month combat tour.

Mr. Bush's speech follows two days of congressionaltestimony by General Petraeus and the U.S. ambassador to Iraq, Ryan Crocker. Both men said security in Iraq has improved, but is fragile and reversible.

Democratic House Speaker Nancy Pelosi expressed the view of lawmakers seeking a clear exit strategy out of Iraq. She told President Bush the human cost of the war has been enormous and has damaged the international reputation of the United States.

Tens of thousands of Iraqis and more than 4,000 U.S. troops have died since the 2003 U.S.-led invasion.