WASHINGTON (CNN) -- If he knew then what he knows now, he might have made some different decisions before the start of the Iraq war in 2003, the outgoing chairman of the Joint Chiefs of Staff told reporters Friday.



Outgoing Joint Chiefs Chairman Gen. Peter Pace says he now thinks more troops were needed at the war's start.



"One of the mistakes I made in my assumptions going in was that the Iraqi people and the Iraqi Army would welcome liberation, that the Iraqi Army, given the opportunity, would stand together for the Iraqi people and be available to them to help serve the new nation," Gen. Peter Pace said.



But "they disintegrated in the face of the coalition's first several weeks of combat, so they weren't here," Pace said.



Had he known that would happen, he would have recommended more troops be sent at the outset of the Iraq war, he said.



In addition, Pace said, if he had been asked in January 2006 whether the United States should build up its Army and Marine Corps contingents in Iraq, he would have said no, because the plan at the time was to build and equip an Iraqi Army and turn over security duties to it.



The force was built and equipped, Pace said, but the February bombing of the Golden Mosque -- one of the holiest Shiite sites -- ignited long-simmering tensions between Sunni and Shiite Muslims, further destabilizing the region and cutting short any plans for U.S. troop reduction.



Thousands of people have died in reprisal killings and bombings since the attack.



Still, Pace said, "Given what I knew at the time, I'm comfortable with the recommendations that I made." Any errors that were made are to be learned from, he added. Watch how Pace details the mistakes made at Iraq war's start »



And he continued to voice his support for the Iraq invasion.



"Twenty-six million Iraqis have the opportunity now," he said. "They are working their way through 3½ decades of being trod upon, held down, no opportunity at all for freedom of expression, for living their lives the way they wanted to, for picking [their] leaders."



Pace will retire when his two-year term ends this month.



Also Friday, Defense Secretary Robert Gates -- in his first public comments since President Bush announced Thursday night he was accepting the Iraq troop level recommendation of Gen. David Petraeus -- noted all Bush's senior military advisers are in agreement with those recommendations.



Gates said he asked Pace and Adm. William Fallon, the head of U.S. Central Command, to begin examining U.S. options in Iraq months ago, knowing that Petraeus -- the top U.S. commander in Iraq -- was doing the same.



"I wanted the president this month to have the benefit of more than one senior military voice as he considered the next steps in Iraq," Gates said. "I also did not want Gen. Petraeus hanging out there all by himself.



"While the analyses of the Joint Chiefs of Staff, CentCom and Gen. Petraeus varied in emphasis and approach, all of the president's senior military advisers are in full agreement with the recommendations made by Gen. Petraeus," he said.



The United States' next steps in Iraq, among other things, "had to avoid even the appearance of American failure," Gates said.



"Extremist Islam was dramatically empowered by defeating the Soviet Union in Afghanistan. The first attack against us by the extremists, the World Trade Center in 1993, was launched from Afghanistan just four years after the last Soviet soldier left there.



"Should the jihadists be able to claim a victory in Iraq over the United States, the sole remaining superpower, I believe it would empower them worldwide far, far more than their victory over the Soviets," Gates said. "The regional consequences would be significant and highly destabilizing." E-mail to a friend
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question: When does the term end?, answer: this month. | question: Who wanted to use their voice?, answer: Pace | question: when will the term end?, answer: this month. | question: What joint Chiefs of Staff chairman says he thought Iraqis would welcome liberation?, answer: Gen. Peter Pace | question: What were the joints?, answer: Chiefs of Staff