"American troops will be leaving as quickly as possible, but they won't be leaving until we have completed our mission," Bush said in a wide-ranging interview with the Post aboard Air Force One on Friday.

In the interview, Bush twice declined to endorse Secretary of State Colin Powell's recent statement that the member of Americans serving in Iraq could be reduced by year's end.

Bush said it is premature to judge how many US men and women will be needed to defeat the insurgency and plant a new and sustainable government in Iraq. He also declined to pledge to significantly reduce US troop levels before the end of his second term in January 2009.

"The sooner the Iraqis are..better prepared, better equipped tofight, the sooner our troops can start coming home," he said.

A new report released last week by US intelligence agencies warned that the war in Iraq has created a training ground for terrorists. Bush called the report "somewhat speculative" but acknowledged "this could happen."

There are currently about 150,000 US troops in Iraq, including some 12,000 soldiers added to boost security in the country beforethe elections on Jan. 30.