Yeah, as long as they keep issuing these "wanings" then their jobs & the enormous amount of $$ that's being spent are justified.
And if you'd been warned on Sept 10th that there was a "threat of terrorism" the next day, and you were either flying or working in the WTC, would you have stayed home/off the plane/away from the WTC? No way. So, even this warning the day before would have been useless.