In the 80s I was stationed on a Korean Air Force Base. While out for an evening walk, I heard the most horrific screams coming from one of the guard towers. I concluded a ROK soldier had been caught sleeping on duty, and was suffering the consequences. 23 years later, the painful sound is still clear in my memory. Imagine a hot cigarette to the tender forearm, or maybe pliers tightly gripping a mans intimate parts.
Under interrogation, they confessed to being spies. I suspect something more severe than waterboarding was employed.