US Republican presidential candidate Donald Trump has repeated his promise to bring back waterboarding, a harsh interrogation technique that President Barack Obama and others have called torture.

"Let me ask you a question. On the other side, they chop off our young people's heads and they put them on a stick," Trump told a crowd of supporters at a campaign stop in Columbus, Ohio. "On the other side, they build these iron cages, and they'll put 20 people in them and they drop them in the ocean 15 minutes and pull them up 15 minutes later. Would I approve waterboarding? You bet your ass, in a heartbeat," he said to cheers.

On 22 November, Trump spoke on the ABC's This Week programme and said that if elected he would bring back waterboarding as an interrogation technique for suspected terrorists. "I would bring it back, yes. I would bring it back. I think waterboarding is peanuts compared to what they'd do to us," he said. "We have to be strong. You know, they don't use waterboarding over there; they use chopping off people's heads."

In October, the US Senate overwhelmingly approved a defence policy bill that would ban waterboarding and other harsh interrogation techniques.