They aren’t quiet. They all have given extensive quotes to the media, and all are responsive to private inquiry.
At a White House press conferene on December 17, 2001, Ari Fleischer said: “There is nothing that has been final that has been concluded. But the evidence is increasingly looking like it was a domestic source. But, again, this remains something that is not final, nor totally conclusive yet. ...I can just report to you the information that I’ve heard. I can’t give you the scientific reasons behind it. But you can assume that they’re based on investigative and scientific means.” He emphasized: “There’s a big difference between the source of it and who sent it, because the two do not have to be tied.”