As British Home Secretary Theresa May confirms that the packages in planes departing Dubai and the UK for the US indeed contained explosives powerful enough to destroy a cargo plane (and possibly a passenger plane, had they been on one), Iran continues to maintain that no explosives have been found.
Bower says bomb squads often keep these explosives on-hand to destroy suspicious packages, and he says terrorists might well have chosen to use a binary explosive for the sort of plot described today.