A day after President Trump proclaimed the torture of enemies and terrorists "absolutely" works, Sen. John McCain offered a sharp rebuke, telling reporters in Philadelphia that such tactics run counter to the country's principles.

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"When he brings up this issue of torture again, I have to speak up -- I have to speak up, I have to -- I have no choice on that," McCain said, later adding, "Because of legislation, because of my own personal experience, because of everything that I've seen."

McCain said that prominent generals and senior military officials "will tell you: It. Does. Not. Work."

He cited the repeated, but largely ineffective, waterboarding of Khalid Sheikh Mohammed, mastermind of the 9/11 terrorist attacks.

McCain also said U.S. law is clear and leaves no wiggle room for re-opening the idea of torturing detainees, though Trump, in his ABC interview, said the country must "fight fire with fire" when confronting extremists.