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Did Holder ever say what status he thought Atta (had he survived) and Moussaoui should have?
Seems to me there's room to believe he would have simply considered them criminals, because that's the common sense answer. That situation is very different from (supposedly) capturing people in an overseas shooting war. And Holder was never in a position (an official one, that is) to make any practical decisions about Gitmo inmates, was he?
Further, we can't tell much from the quote referencing Vietnam. Again, he seems to be stating common sense there---that there is precedent for holding POWs for the duration of a conflict. Of course that ignores details such as a potential inability to successfully negotiate a prisoner exchange, etc., and perhaps he knows no more about the actual history of the war (or any war) than do most Americans.