WASHINGTON (CNN) -- Former Vice President Dick Cheney on Sunday said his claim that enhanced interrogation techniques -- including waterboarding -- produced critical post-9/11 information was supported by a pair of intelligence reports released last week.
Former VP Dick Cheney says enhanced interrogation techniques persuaded subjects "to cooperate."
"The enhanced interrogation techniques were absolutely essential in saving thousands of American lives," he told "Fox News Sunday."
However, the two dossiers that were declassified at Cheney's request do not disclose what kinds of techniques were used to elicit the intelligence. The only method occasionally cited by the reports is a routine one -- using information from one detainee to gain details from another.
The two reports surfaced as the latest ammunition in the debate over whether the use of controversial interrogation techniques like stress positions, wall slamming, and waterboarding -- considered torture by critics -- helped prevent terrorist attacks.
Cheney said the reports prove that two top al Qaeda suspects, Khalid Sheikh Mohammed and Abu Zubayda, "were uncooperative at first."
But "the application of enhanced interrogation techniques, specifically waterboarding -- especially in the case of Khalid Sheikh Mohammed -- is what really persuaded him he needed to cooperate," Cheney said
A U.S. government official with knowledge of the interrogation program told CNN that while the chronology is not spelled out in the two reports, Mohammed's information became "more voluminous and accurate" after he was exposed to waterboarding 183 times.
The official declined to be identified because he was not authorized to speak on the subject.
Zubaydah also talked more after being subjected to waterboarding, according to a third document -- a 2004 CIA inspector general's report that was released last week.
"It is not possible to say definitively that the waterboard is the reason for Abu Zubaydah's increased production," says the report, "or if another factor, such as the length of detention, was the catalyst. Since the use of the waterboard, however, Abu Zubaydah has appeared to be cooperative."
It also says that before his waterboarding, Mohammed provided little information.
But the report is cautious on whether the enhanced interrogation techniques, or EITs, approved by the Bush administration helped the interrogation program get results.
"There is no doubt the program has been effective," the 2004 report says. "Measuring the effect of the EITs, however, is a more subjective process and not without some concern."
The CIA report also does not say whether the techniques -- which have since been banned -- were the only way to get the detainees to talk.
"The effectiveness of particular interrogation techniques in eliciting information that might not otherwise have been obtained cannot be so easily measured," it says.
And one of Zubydah's interrogators, former FBI special agent Ali Soufan, told a Senate hearing in May that waterboarding him was unnecessary. Any useful information interrogators got from him either was or could have been produced without "enhanced" techniques, he said.
Soufan said Zubaydah stopped talking after CIA contractors took over and began using harsh techniques, which he testified were "ineffective, slow and unreliable, and harmful to our efforts to defeat al Qaeda."
Zubaydah was subjected to waterboarding 83 times in August 2002, according to Bush administration documents released in April; Mohammed was waterboarded 183 times in March 2003, according to the documents.
U.S. authorities prosecuted Japanese officers who used waterboarding against American prisoners in World War II. But Bush administration lawyers argued the tactic did not violate U.S. laws against torture as long as interrogators had no intent to cause "severe pain."
Cheney said in May that the interrogations were used only on "hardened terrorists" after other efforts failed -- and "in a few cases, that information could be gained only through tough interrogations."
And there was also time pressure, the U.S. official with knowledge of the interrogation program told CNN.
"Time was deemed to be of essence. There was fear of a pending attack" in the aftermath of the September 11, 2001, terror attacks.
"Could you have gotten the information some other way? We'll never know," said Peter Bergen, CNN terrorism analyst, who doubts the information divulged after waterboarding saved American lives.
"Did it really avert imminent terrorist attacks, according to these documents? No," he said. "Khalid Sheikh Mohammed certainly revealed a lot of information after being waterboarded ... but it turns out these plots were just talk."
But Cheney said enhanced interrogations contributed to most of the successful arrests of al Qaeda members.
"I think they were directly responsible for the fact that for eight years we had no further mass casualty attacks against the United States," he said Sunday.
CNN's Pam Benson and Brian Todd contributed to this report.