Information, please

Josh Marshall at TalkingPointsMemo posted an exchange that took place during Friday morning's White House press briefing. I plucked out this part.

Question: They had nothing to do with September 11th, the Iraqis.

Mr. [Scott] McClellan: Oh, I beg to differ. September 11th taught us that we are living in a dangerous new world. September 11th -

Question: So you attack somebody who is innocent?

Mr. McClellan: September 11th taught us that we must confront gathering threats before it's too late. September 11th changed the equation.

Okay, here's the deal. In order for the lesson of 9/11 to be that "we must confront gathering threats before it's too late," the White House must have known there was a "gathering threat" from al-Qaeda against which it failed to act until it was "too late." Otherwise, there is no connection between the experience and the lesson to be drawn from it. So just what was the threat of which the White House was aware and just what actions did it fail to take?