Imminent Attack?

Here is a warning from Israpundit. "Israeli Counterterrorism expert, Juval Aviv, met recently with reporters at Fox News and revealed information, which he believes is accurate, concerning an imminent Al Qaeda attack on five to seven American cities simultaneously." Even if this doesn't happen, isn't it better to be prepared than continue to be self-destructively apathetic and politically correct? It reminds me of the story of the boy who cried wolf.