I can imagine the difficulty of trying to decide whether or not to inform a population about a potential terrorist attack. On the one hand, the chance of costs in lives and treasure from the panic that can ensue from the warning alone is guaranteed while the actual terrorist strike is not. Of course, the cost to a government who fails to inform the public about a threat that does come to pass (clearly there is a constant stream of threats to the US public from various sources) would be large enough to cost an election. Hell Bush paid a huge price based on the pure fiction that he A) knew it was going to happen or B) allowed the perpetrators to leave early and other fictitious nonsense. One can hear this calculous in the way this potential threat is presented.