The CIA has reasoned that since waterboarding has no lasting damage, physically, that it is therefore acceptable. And since it instills in the victim a sense of terror and panic, they reason they can make people talk without resorting outright torture and mutilation.
But lasting physical damage is not the measure for torture. Waterboarding is outright torture, the Allied ceratainly thought so when the executed people guilty of applying torture in the world war II. An the UN thinks so
The defitiion of torture, from 1984 by the united nations
quote:
For the purposes of this Convention, the term "torture" means any act by which severe pain or suffering, whether physical or mental, is intentionally inflicted on a person for such purposes as obtaining from him or a third person information or a confession, punishing him for an act he or a third person has committed or is suspected of having committed, or intimidating or coercing him or a third person, or for any reason based on discrimination of any kind, when such pain or suffering is inflicted by or at the instigation of or with the consent or acquiescence of a public official or other person acting in an official capacity. It does not include pain or suffering arising only from, inherent in or incidental to lawful sanctions.
Waterboarding inflicts severe mental suffering on the victim, and is by definition torture. To say otherwise is to lie.