I bet that there were no explosives—all of this reeks of “Wag the Dog.”
As far as I can tell they did not know if the potential attack was a dirty bomb, high explosive, or the old mail bomb which would kill or maim the guy opening the package. First reports of the suspicious object in Philly said there WAS radio activity present.
How on earth could Obama let these planes take off, let alone land in the USA or England. They could have been intended to explode like Lockerbe. Or they could have radio-logically poisoned many people.