Credit: Lucy Nicholson/Reuters Trump called for the reinstatement of waterboarding just hours after the attack on an airport in Istanbul that killed more than 40 people.

Presumptive Republican presidential nominee and ardent waterboarding supporter Donald Trump wants America to be much tougher on suspected terrorists. So tough, in fact, that we must to do "the unthinkable" when it comes to prisoner interrogation, he said Thursday.

Trump, during an interview with New Hampshire's NH1, was asked about his calls to reinstate waterboarding following Tuesday's attack on Istanbul's Ataturk Airport that killed at least 44 people. Trump has enthusiastically endorsed tactics now widely regarded as torture, and has discounted recent criticism from Sen. John McCain (R-Ariz.), who said the interrogation technique "was not the American way."

“Well it's not the American way to have heads chopped off and have people drowning in steel cages," Trump said, presumably referring to videos released by the Islamic State that show such execution methods. "And so we can have our disagreements, but we’re going to have to get much tougher as a country. We’re going to have to be a lot sharper and we’re going to have to do things that are unthinkable almost.

"Unthinkable, when you look at what’s happening to us, when you look at what’s going on in this country and throughout the world and we don’t want, you know they’re allowed to cut off heads and they’re allowed to chop off heads, and we can’t waterboard. So people can have disagreements, but I feel we have to get much, much, stronger, tougher and smarter."

Hours after the Istanbul attack, Trump called for the need to fight "fire with fire" in the battle against terrorism. On waterboarding, he said, "I like it a lot. I don't think it's tough enough."

Terrorists "probably think we're weak, we're stupid, we don't know what we're doing, we have no leadership," he told a crowd in Ohio.

A day later, McCain— a former prisoner of war -- said such a position is "not the United States of America. It's not what we are all about. It's not what we are."

The International Red Cross classified waterboarding as torture in 2014 and said the practice violates the Geneva Conventions.

Editor's note: Donald Trump regularly incites political violence and is a serial liar, rampant xenophobe, racist, misogynist and birther who has repeatedly pledged to ban all Muslims -- 1.6 billion members of an entire religion -- from entering the U.S.