Bush is "very smart -- a true idealist," who had "immense simplicity in how he saw the world," Blair wrote in 'A Journey,' his newly released memoir. "Right or wrong it led to decisive leadership."
Released last week, the book comes at a time when the United States is ending its combat mission in Iraq. The war was spearheaded by Bush and managed to destroy Blair's reputation in Britain, where he is still considered "Bush's poodle" for following the United States and other allies into the conflict.
While most of British politicians have recanted their support for the military mission, Blair said he "can't regret" it.
"I can say that never did I guess the nightmare that unfolded, and that, too, is part of the responsibility. The truth is, we did not anticipate the role of al-Qaida or Iran," he writes Whether we should have is another matter; and, if we had anticipated, what we would have done about it is another matter again."
The British mission in Iraq, from the start of the invasion in March 2003 until April 30, 2009, claimed the lives 179 British troops. Blair said last month he would donate all the book's proceeds and his estimated $7 million advance to a charity for ex-service members and in his book writes about the anguish he feels over those deaths.
The move has done little to repair his reputation at home. Blair had to cancel his Wednesday book signing event in London because of security concerns linked to large anti-war protests in the British capital. The decision came two days after protesters threw eggs and shoes at him at a signing Saturday in Dublin.
Repeating the rhetoric of his statements on Iraq to a British inquiry in January, Blair in the book defends his decision to go to war despite the absence of weapons of mass destruction.
"The intelligence was wrong. We admitted it. We apologized for it," he writes. "Humans make errors and, given Saddam's history, it was an understandable error."
In an interview with ABC this week, Blair said Iran was on a similar trajectory than Iraq, adding that if he was a leader today, he "wouldn't take the risk" of letting Iran building a nuclear weapon.
"I would tell them they can't have it, and if necessary they will be confronted with stronger sanctions and diplomacy, but if that fails, I'm not taking any option off the table," he said.
Blair, a Democrat, in his book reveals his good official and private relationship with Bush, a conservative, detailing several meetings with him during the build-up to Iraq war in London, Washington and at Bush's ranch in Crawford, Texas. Despite their many policy differences over issues such as climate change and the Middle East peace process, the president, Blair writes, "had genuine integrity and as much political courage as any leader I ever met."
"He was basically considered a right-wing Republican bastard for getting rid of hostile brutal dictatorships and insisting they be replaced not with friendly brutal dictatorships but with an attempt at liberal democracy," Blair writes.
Aside from the praise for Bush, Blair writes that Bill Clinton was his favorite U.S. leader, and his "political soul mate."
"He is the smartest politician I ever came across," Blair said of Clinton in the ABC interview.
The affair between Clinton and Monica Lewinsky, Blair suggests, could be linked to "his inordinate interest in and curiosity about people."
"In respect of men, it was expressed in friendship; in respect of women, there was potentially a sexual element."
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