[Mrs. Don-o]

We were discussing torture as a tool for "enhanced interrogation." The point here is not pain and fear in themselves, but the deliberate infliction of such in order to impair another person's rational faculties --- their control over their own thoughts and actions.

Pain and fear in training are a different thing altogether. I believe they're intended actually to increase the trainee's ability to control his thoughts and actions despite extreme duress.

[G Larry]

If you read your response carefully, you will find you’ve answered your own question.

The troops are trained to withstand “enhanced interrogation”.
The enemy is aware of this also.
In the unique “battlefield” of terrorism, “enhanced interrogation” is clearly in the center of that battlefield.
KSM was clear that waterboarding would not and was not intended to kill him, as he’d endured several sessions before giving up the necessary information.
He simply tired of the process and provided the data.
It is important to keep in mind that only about 3 Terror leaders were waterboarded, and careful deliberation was given before approving each case.