ARI SHAPIRO, HOST:

We're going to hear next how the issue of torture is playing out in the presidential race. Ahead of today's New Hampshire primary, the GOP contenders have been weighing in on the use of waterboarding by U.S. officials on alleged terrorists. Some of the candidates endorse this practice, which many other people consider torture. We asked NPR national security correspondent David Welna examine some of the recent claims about waterboarding. Here's his report.

DAVID WELNA, BYLINE: In a debate on ABC News Saturday night, moderator David Muir reminded Ted Cruz of a moral judgment the Texas Republican senator once made. Torture, Cruz had said, is wrong. Unambiguously, period. So Muir had a question.

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DAVID MUIR: Senator Cruz, is waterboarding torture?

TED CRUZ: Well, under the definition of torture, no, it's not. Under the law, torture is excruciating pain that is equivalent to losing organs and systems. So under the definition of torture, it is not. It is enhanced interrogation, it is vigorous interrogation, but it does not meet the generally recognized definition of torture.

WELNA: Cruz appeared to be referring to a now-discredited 2002 Bush administration memo used as the legal basis for waterboarding. That memo is sharply at odds with the United Nations convention against torture ratified by the U.S. Senate under the first President Bush. The International Committee of the Red Cross also considers waterboarding torture. And the U.S. executed Japanese generals after World War II who'd been charged with using water torture against U.S. prisoners of war. At that same debate, Republican front runner Donald Trump vowed he'd bring back the practice of waterboarding and more. The following day, Trump was asked on CNN whether waterboarding actually works.

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DONALD TRUMP: I have no doubt that it does work in terms of information and other things. And maybe not always, but nothing works always. But I have no doubt that it works.

WELNA: Former CIA officials also defend the agency's waterboarding of at least three suspected terrorists. And, they claim, it saved lives. But a massive study of CIA interrogation done by Democrats on the Senate Intelligence Committee reached the opposite conclusion. Waterboarding, the report's summary said, was, quote, "Not an effective means of obtaining accurate information or gaining detainee cooperation." The issue of waterboarding has been seized on by GOP candidates eager to show they're tough on terrorism, but fellow Arizona Republican John McCain, who was tortured as a prisoner of war, went to the Senate floor this afternoon to denounce what he called their bluster about waterboarding.

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JOHN MCCAIN: These forms of torture not only failed their purpose to secure actionable intelligence to prevent further attacks on the United States and our allies, but compromised our values, stained our national honor and did little practical good.

WELNA: McCain noted that Congress enacted legislation last year outlawing the use of torture by any government agency. Sen. Cruz was absent for that vote. So was another Republican running for president, Florida's Marco Rubio. In the debate on ABC News, Rubio refused to say whether he'd bring back waterboarding if elected president.

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MARCO RUBIO: We should not be discussing wide - in widespread way the exact tactics that we're going to use because it allows terrorists and others to practice how to evade us. But there's the bigger part - problem with all this. We're not interrogating anybody right now.

WELNA: That might come as a surprise to several high-profile terrorism suspects whom U.S. officials have interrogated during the Obama administration. It's true such detainees are no longer being taken to Guantanamo and that none are known to have been waterboarded. David Welna, NPR News. Transcript provided by NPR, Copyright NPR.