People who work in counterterrorism are correct in making this point: The fact that 9/11 happened once does mean that something like it could happen again. And the fact that we should have seen it coming the first time—we could have seen it, and we didn’t—instills everyone involved in counterterrorism with a vigilance that manifests as dread and fear. Not a fear of bad things happening, but fear of missing something. A relentless second-guessing. People who take this threat seriously are more on edge than people who don’t.
