Sixty-four-year-old Bush told The Times newspaper among his regrets are "flying a Mission Accomplished banner on the USS Abraham Lincoln in 2003, the premature reduction of US troop numbers in Iraq after the invasion and, above all, the inaccurate information on WMD."
He said, "The reality was that I had sent American troops into combat based in large part on intelligence that proved false."
"No one was more shocked or angry than I was when we didn't find the weapons. I had a sickening feeling every time I thought about it, I still do," he wrote in his book Decision Points, serialised in the London daily. He doubts that WMD might still be hidden in Iraq.
But regardless of mistakes and whatever the death toll in Iraq, removing Iraqi dictator Saddam Hussein was the only moral course of action, the former US President wrote. "There were things we got wrong in Iraq, but that cause is eternally right."
Bush claimed the information extracted from terrorist suspects by "waterboarding" saved British lives by preventing attacks on Heathrow and Canary Wharf. He offered vigorous defence of the coercive interrogation technique. "Three people were waterboarded and I believe that decision saved lives," he wrote.
Bush depicted waterboarding, in which water is poured over a suspect's face to simulate drowning, as morally defensible, legal and effective.
Without the Central Intelligence Agency's use of "enhanced interrogation" there would have been another attack on the United States, he said.
Asked if he authorised the use of waterboarding to get information from the captured Al Qaeda leader Khalid Sheikh Mohammed, Bush was unequivocal, "Damn right!"
In his book, he wrote, "Their interrogations helped break up plots to attack American diplomatic facilities abroad, Heathrow airport and Canary Wharf in London, and multiple targets in the Untied States."
