The invasion of Iraq was an "enormous mistake" that is costing untold lives, strengthening Al Qaeda and breeding a new generation of terrorists, former White House counterterrorism czar Richard Clarke (search) said Saturday.

"We did exactly what Al Qaeda (search) said we would do — invade and occupy an oil-rich Arab country that wasn't threatening us in any way," Clarke said before giving the keynote address at the American Library Association's annual convention in Orlando. "The hatred that has been engendered by this invasion will last for generations."

Clarke, a counterterrorism adviser to the past three presidents, wrote the book "Against All Enemies (search)," which strongly criticizes the Bush administration for making Iraq a top priority and for underestimating warnings about Al Qaeda before the Sept. 11 attacks.

Clarke said the United States will lose the war on terrorism if it loses the battle of ideas against extremists in the Middle East.

"We won the Cold War by, yes, having good strong military forces but also by competing in the battle of ideas against the Communists," Clarke later told the librarians. "We have to do that with the jihadists."

The United States' ideological credibility has been undermined by revelations of the mistreatment of Iraqi prisoners at the Abu Ghraib (search) prison and the release of documents that showed U.S. government attorneys conducted a legal analysis of what constituted torture, Clarke said.

Clarke took issue with some elements of filmmaker Michael Moore's new documentary, "Fahrenheit 9/11," which depicts how the Bush administration allowed Saudi nationals and members of Usama bin Laden's (search) family to leave the United States days after the Sept. 11 attacks.

Clarke said he thought the Saudi government was "perfectly justified" in wanting its citizens to leave the United States out of fears of "vigilantism" by Americans.

The Saudis were not allowed to leave until the FBI cleared them of posing any danger and having knowledge of Usama bin Laden's whereabouts, Clarke said.

Making the incident a big part of the movie was a mistake, said Clarke, who added that he agrees with many things Moore stands for.