The former chief US weapons inspector in Iraq warned on Monday that the United States is in "grave danger" of destroying its credibility at home and abroad if it does not own up to its mistakes in Iraq.
"The cost of our mistakes ... with regard to the explanation of why we went to war in Iraq are far greater than Iraq itself," David Kay said in a speech at Harvard University's John F. Kennedy School of Government.
"We are in grave danger of having destroyed our credibility internationally and domestically with regard to warning about future events," he said. "The answer is to admit you were wrong, and what I find most disturbing around Washington ... is the belief ... you can never admit you're wrong."
The comments by Kay came as the White House sought to fend off accusations from its former anti-terrorism czar, Richard Clarke, who said President George W. Bush ignored the al Qaeda threat before the September 11, 2001, attacks and focused on Iraq rather than the Islamic militant group afterward.
The White House last year cited Iraq's weapons of mass destruction as the main reason for going to war.
Kay resigned his post in January, saying he believed no such arms existed and that the failure to find any such weapons raised serious questions about the quality of prewar intelligence.
Kay, who was part of United Nations weapons probes in Iraq in the early 1990s, said US intelligence there was poor in the decade before the war, relying entirely on international inspectors themselves, Iraqi defectors or intelligence from allies like France and Britain.
He cautioned the intelligence community against jumping to premature conclusions, as it did in Iraq. "One of the most dangerous things abroad in the world of intelligence today actually came out of 9/11 ... the insistence of 'Why didn't you connect the dots?' The dots were all there," he said.
"When we finally do the sums on Iraq, what will turn out is that we simply didn't know what was going on, but we connected the dots - the dots from 1991 behaviour were connected with 2000 behaviour and 2003 behaviour, and it became an explanation and a picture of Iraq that simply didn't exist," Kay said.