The Daily Kos has an interesting timeline that includes changes to our terror alert level and terrorist attacks. Unsurprisingly, there’s not much correlation between them. There are two possibilities here that seem obvious to me. One is that the higher alert level might have prevented terror attacks (unlikely given that there have been no significant domestic attacks since 9/11, regardless of security level), and the other is that terrorists might pay attention to the threat level as well. Ultimately, though, I think that the whole thing is basically a farce. Consider a case where, by monitoring “chatter” about an impending terror attack on US soil, the government feels that it is closing in on a significant arrest. Just for fun, say it’s Osama bin Laden. Do we really believe that we’d tip off the terrorists who we think we can capture by jacking up the terror alert level on short notice, even though a terror attack is incredibly likely? I doubt it.