Feb. 8, 2011— -- Former Defense Secretary Donald Rumsfeld declares that his biggest regret in office was not convincing President Bush to accept his resignation after the Abu Ghraib prison scandal, and said the country and the Pentagon probably "would've been better off" if he had left office in 2004.
In an exclusive interview with ABC's Diane Sawyer, Rumsfeld also said the enhanced interrogation techniques he approved for use on the so-called "20th hijacker" -- including forced stress positions and removal of "comfort items" -- produced invaluable intelligence.
For that, he said, he has no regrets about the tactics he approved to gain intelligence from Mohammed al-Qahtani.
"Oh I don't have any regrets at all," he told Sawyer.
But does have a big regret stemming from his time in office - staying in office during what he calls a period of "damaging distraction," as photos of abused detainees at Abu Ghraib circulated around the globe. He twice wrote letters of resignation to the president, but was convinced to stay on both times.
"That was such a stain on our country," he told Sawyer. "To think that people in our custody were treated in that disgusting and perverted and ghastly way -- unacceptable way."
"There wasn't an easy target," he added. "And so I stepped up and told the president I thought I should resign. And I think probably he and the military and the Pentagon and the country would've been better off if I had."
Watch Part Two of Diane Sawyer's Exclusive Interview With Donald Rumsfeld on ABC's "World News With Diane Sawyer" on Tuesday, Feb. 8.
Click here read more about Part One, which aired on "World News" Monday, Feb. 7
Rumsfeld asserts that the harsh interrogation tactics he authorized for use against high-value terrorism suspects helped U.S. authorities save lives, including in the case of Mohammed al-Qahtani.
"Qahtani, who was the 20th hijacker, they say -- he gave a lot of information," Rumsfeld said. "And it was very helpful to our interrogators and to the United States government in saving lives."
He added: "And I think that the fact that we haven't had an attack in a decade is a credit to that administration, the Bush administration, and to [President Bush]."
Still, he writes that he was "surprised and troubled" that interrogators went further than his orders allowed in some cases, particularly in interrogating Qahtani at Guantanamo Bay.
Qahtani would be subjected to sexual humiliation and long periods of sleep deprivation and isolation while in custody at Guantanamo, and his heartbeat at one point dropped to 35 beats per minute.
Rumsfeld said he only learned the details of such treatment after the fact -- and that interrogators went further than he had authorized.
"I didn't approve any of that," Rumsfeld said in the interview. "And when I found out that they had done some of those things, the people who had done things that had not been approved were dealt with. They were stopped and prosecuted."
Rumsfeld dismissed suggestions that interrogation techniques he authorized led to human-rights abuses against detainees at Guantanamo, or at Abu Ghraib. But he clearly disapproves of Qahtani's handling.
"Some of what took place sounded to me as if the interrogation plan may have gone beyond the techniques I had approved," he writes in his new memoir, "Known and Unknown," which is being released today.
"The combination and frequency of techniques interrogators had used with Qahtani called into question their appropriateness, at least in my mind," he said. "They may not have been in keeping with the intent of my January 2002 order that all detainees in the custody of the Defense Department were to be treated humanely."
Rumsfeld rejected the idea that his actions led to treatment that could be considered "torture," saying his directives were "precisely delivered."
"There were 12 reports -- independent reports in the Pentagon and by external groups," he told Sawyer. "Every single one said there was not a shred of evidence that there was anything to do with senior military or senior civilian leadership that led to torture."
Perhaps the highest-profile such report, authored by a Rumsfeld-appointed panel led by former Defense Secretary James Schlesinger to investigate abuses at Abu Ghraib, did not place direct responsibility at Rumsfeld's hands.
But the panel found that Rumsfeld should have sought "a wider range of legal opinions" before developing his original policies. And the report found that the techniques authorized "became far more problematic when they migrated [from Guantanamo to Afghanistan and Iraq] and were not adequately safeguarded."
Rumsfeld also defended his famous comments to a soldier in Kuwait -- that "you go to war with the Army you have, not the Army you might want or wish to have at a later time."
"Was it insensitive? No, go back and read the whole thing," he said. "I cared deeply about the troops. And my answer reflects it."
The interview with Sawyer turned emotional at times, particularly as Rumsfeld discussed his family -- his relationship with his father, his children's substance-abuse problems, and an illness that struck his wife, Joyce, as the war in Iraq worsened.
In April 2003, with post-invasion Iraq descending into chaos, Rumsfeld recalls that Joyce was near death due to a medical error. (She has since recovered fully.)
"She was dying," he writes. "I remember looking at Joyce in the hospital bed. And she looked just like her mother who'd died in her 90s. And she was that bad."
Bush ultimately decided to replace Rumsfeld on the eve of the 2006 congressional elections, as a Democratic takeover in Congress seemed likely. Vice President Dick Cheney -- Rumseld's former aide, and a friend for nearly four decades -- delivered the news.
"I said, 'You're right. Tell him he's done the right thing,' " Rumsfeld recalled of his conversation with Cheney.
Rumsfeld said the policies of the Bush administration proved their worth over the years -- as evidenced by the fact that the Obama administration has kept so many of them in place.
"For all the criticism of President Bush and the people working around him for the things he put in place -- the Patriot Act, the Guantanamo Bay [prison] and various things, military commissions -- you know, a lot of people criticized them and they fussed at it," he said. "[President] Obama did. [Sen. John] McCain did. Republicans, Democrats, the press, the media.
"The fact is, they're still there," he said. "Why are they still there? They're there, because they make sense in the 21st Century. They're needed. And the new administration has not been able to figure out a better way to do it."
But he does fault Bush for not engaging the American people in the fight ahead -- and for labeling the fight a "war on terror," instead of one waged against radical Islam.
"We needed people -- moderate Muslims in the world to understand that their religion was being hijacked. It was being hijacked by radicals," he said. "We never stepped up in the Bush administration and engaged in the competition of ideas to any really great extent. And nowhere near as effectively as we need to eventually."
"Proceeds from the sales of Known and Unknown will go to the veterans charities supported by the Rumsfeld Foundation."