I had to repost this because it makes so much sense. And thank god they never got a hold of any WMDs!
As long as we're tossing theories around how about this: Suppose the origins of the shells and/or their contents might embarass someone. Perhaps that somone is someone whose cooperation the Bush Administration is trying to acquire when dealing with other headline grabbing world events. Discretion would provide a useful trump card. Perhaps it's time to play that card.
Who says they didn't?