It's been an article of faith for the Bush administration that the invasion of Iraq was the right thing to do.
However, the man now in charge of running that war said he is not sure.
Defense Secretary Robert Gates' stunningly candid answer came in an interview with New York Times columnist David Brooks.
Gates: 'I Don't Know'
Asked if the invasion of Iraq was worth doing, Gates first rephrased the question: "If I'd known then what I know now, would I have done the same? I think the answer is, 'I don't know.'"
Compare that to the words of President Bush, who has said consistently and forcefully that the invasion was the right thing to do.
"I strongly believe we did and are doing the right thing," Bush said May 25, 2006.
"Removing Saddam Hussein was the right thing for world peace and the security of our country," he said again April 6, 2006.
"It is a necessary war to secure our peace," the president said July 12 of this year.
Asked to clarify the defense secretary's comments on the war, Pentagon officials referred back to his confirmation hearing in December where Gates said it was "too early to tell" if the invasion was the right decision.
Gates in 'Stark Contrast' with Bush on Iraq Conflict
The co-author of the Iraq Study Report said Gate's views on the Iraq conflict are in "stark contrast" to the president's.
"You couldn't get a greater contrast," said Lee Hamilton, co-author of the Iraq Study Report.
"It's refreshing to see a secretary of defense who has an appreciation of military power but also has an appreciation of the limitations of military power," he said.
Gates supports the president's strategy on the so-called surge, but he has a starkly different view about what can be accomplished in Iraq.
In another interview Monday, Gates told the Wall Street Journal he is focused on bringing "a long-term stabilizing presence."
Absent in the interview was any talk of spreading democracy -- once the centerpiece of the Bush administration's foreign policy.
"The ultimate goal of ending tyranny in our world," Bush has said.
Gates sought to scale back that goal this week during a speech.
"We must be realists and recognize that the institutions that underpin an enduring free society can only take root over time," Gates said Monday in an address on the Future of Democracy at the College of William & Mary.
Former presidential adviser David Gergen said the two men have different views about the 4-year-old conflict.
"The president said in his second inaugural we're going to spread democracy around the world, Bob Gates is coming in and saying, 'Hey, wait a minute, this takes a long time, let's be patient, we're not on a crusade,'" Gergen said.