I would bring back waterboarding, and I would bring back a hell of a lot worse than waterboarding… Torture does work.

~ Donald J. Trump (1946-06-14 age:71) 2017-01-27

Trump said that Defense Secretary James Mattis disagreed with him, and Trump would defer to Mattis.

Whether torture works should not be a matter of opinion. Surely the military has kept records on torture. They routinely tortured all POWs (Prisoner Of Wars) in Iraq so they have plenty of data. They would know what percentage of those tortured:

The US daily violates the Geneva Conventions which George W. Bush called quaint.