Khalid Sheikh Mohammad, known as KSM, is widely considered the architect of the attack, in which hijackers seized passenger planes and crashed them into the World Trade Center in New York and the Pentagon outside of Washington.

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He was subjected to a number of “enhanced interrogation techniques”, including “waterboarding” - simulated drowning - at least 183 times before the practice was banned by the US government.

Yikes, but also, literally planned 9/11, but yikes.