"Still, Chertoff said there are not enough indications of an imminent plot to raise the current threat levels nationwide. And he indicated that his remarks were based on “a gut feeling” formed by past seasonal patterns of terrorist attacks, recent al-Qaeda statements, and intelligence he did not disclose. There is an assessment “not of a specific threat, but of increased vulnerability,” he added."
I am reminded of an episode of CSI New York, where one of the detectives had a hunch that one of the players was hiding something. The lead detective told him, your hunches are good, but you need to bring me evidence. I want to tell Mr. Chertoff the same thing, it is great that you have this feeling that we need be to aware as a nation of a potential attack, now go out there and find something that you can show us to make it solid. I don't want leaders who only deal with what is in the reports, they have to lead and make decisions based on their feelings. However, if you want the public to take what you are saying seriously you can't come out and say, "I have a hunch America might be attacked soon".