WASHINGTON (CNN) -- The incidents that first left then-White House press secretary Scott McClellan "dismayed and disillusioned" about Washington involved the surreptitious release of classified information, McClellan said Thursday.
Scott McClellan's book is sparking strong reactions from his former White House colleagues.
The first of the "defining moments," McClellan told NBC's "Today" show, was when CIA operative Valerie Plame's name was leaked to the media.
The second, he said, was when he learned that President Bush had secretly declassified a report on Iraq so Vice President Dick Cheney and Cheney aide I. Lewis "Scooter" Libby could disclose it to reporters.
"We had been out there talking about how seriously the president took the leaking of classified information, and here we were learning that the president had authorized the very same that we were criticizing," McClellan said, the day after his controversial memoir hit bookstore shelves.
Current and former Bush administration officials have roundly refuted the details outlined in McClellan's "What Happened: Inside the Bush White House and Washington's Culture of Deception." Watch how the White House is slamming McClellan's book »
In response to McClellan's suggestion in the "Today" interview that the White House manipulated intelligence in the run-up to the war, a senior administration official said, "Scott McClellan's assertions about the administration's decision to go into Iraq are just flat-out wrong and not supported by the facts."
The official was not willing to be identified because he was not authorized to speak about the book.
While McClellan asserts the White House would prefer him to stay silent, the official said, "No one at the White House ever told McClellan not to talk about his experience."
As White House spokesman, McClellan defended Bush's policies during much of the Iraq war, the aftermath of Hurricane Katrina and the scandal that followed the leak of Plame's identity.
But he now says the administration was mired in propaganda and political spin and played loose with the truth at times.
In March 2007, Libby was found guilty of perjury, obstruction of justice and making false statements for lying about what he said to reporters about Plame. Bush later commuted Libby's 2½-year sentence prison sentence, but left in place Libby's fine and probation.
McClellan told "Today" on Thursday, "I had been assured -- and [then-senior adviser] Karl Rove and 'Scooter' Libby both -- I asked them point-blank, 'Were you involved in this in any way?' And both assured me in unequivocal terms, 'No, we were not involved.' " See what else McClellan's book alleges »
"And Rove even told the president, and the president and VP directed me to go out and exonerate 'Scooter' Libby on this, and that's when I went to 'Scooter' and asked him the question," McClellan said.
The former press secretary told "Today" that he once promised the White House press corps that he would write a tell-all book when his days as Oval Office spokesman were done.
The office of White House counsel told McClellan at the time he was not permitted to discuss how the information was leaked, he said.
"My hands were tied," McClellan said. "I said at the time, some day I look forward to talking about what I know and my involvement in defending the White House in terms of the leak episode. And so I do this in the book. That was kind of a launching-off point for the book, but the book is really larger than that. The book is about how things went off course." See what other former White House officials said in tell-alls »
McClellan also discussed how, he said, Bush decided to go to war against Iraq soon after the 2001 terrorist attacks on the U.S. The president ordered aides to make arrangements for it, McClellan told "Today."
"I think very early on, a few months after September 11, he made a decision that we're going to confront Saddam Hussein, and if Hussein doesn't come fully clean, then we're going to go to war. There was really no flexibility in his approach," McClellan said. "Then it was put on the advisers: How do we go about implementing this? How do we go about doing this?" Watch what another former press secretary has to say »
Despite the details in McClellan's allegations, a former White House counselor said McClellan had no way of knowing whether Bush reviewed all the facts before going to war in Iraq.
"I don't think he was in a position to know this," said Dan Barlett, explaining McClellan was deputy press secretary at the time.
Bartlett said McClellan would not have had access to the "meetings and deliberations that the president participated in."
"Scott McClellan was not the press secretary. He was the deputy press secretary who dealt with domestic issues," said Bartlett, who like McClellan, began working for Bush when he was governor of Texas in the 1990s.