Exactly right: Patrick Ruffini says briefly and well what I spent way too long saying here:

Either someone is a threat, or they're not. Either someone has the intent to harm you or they don't. September 11th, and to some extent, the fluctuating threat levels since, shows us just how tricky it is to project just how "imminent" a threat is. Is an attack coming three days down the road, or three years? It's almost impossible to tell. This is why it's incoherent to say Saddam was a threat, but not an imminent threat. As September 11th showed, one can have vague chatter one day and a planes crashing into buildings the next. At what point did we understand an attack on such a scale to be "imminent?" Never, and even if it were possible, it would be for a vanishingly short moment at one minute to midnight. Do we really want to let things slide that far?

The best defense is a good offense.

Perfect.