Trump said he would "bring back a hell of a lot worse than waterboarding" during Saturday's Republican presidential debate. Waterboarding is a form of torture and banned as a war crime.
"I'd go through a process and get it declassified frankly, and I would certainly, waterboarding at a minimum," Trump told CNN's Jake Tapper.
Trump said while it might not work always, but is still a useful interrogation technique.
"You can say what you want, I have no doubt that it does work in term of information and other things," he said.