Richard-

The US claims that its information came from "enhanced interrogation"

A more correct phrasing of what you've posted above would be that there's an active debate within the US of whether any information derived form "enhanced interrogation" was useful or critical. It seems that the alias of the courier did first come from "enhanced interrogation" but that name was meaningless until other prisoners were interviewed with more conventional interrogation techniques and provided corroboration and more detail. Linking the courier to a phone call was the next step and then tracking him to Bin Laden's hide-a-way was the final piece in the puzzle.

Charley Noble