I don't really know, but I suspect that many would be horrified by the deliberate use of American military force against American civilians, no matter how good the argument for it. (Arguably, it would actually be use of force against the terrorists with inevitable civilian casualties, but I suspect many wouldn't see it that way, and many who did would still be horrified.) And all a cover-up requires is that someone judge the same way (or just think it likely enough), justified or not.