In other words, the "wall of separation" constructed by Jamie Gorelick made it virtually impossible for U.S. authorities to stop Ahmed Rassam, the "Millenium Bomber," by design or intention. It was left to blind luck. The NSC's Millennium After Action Review — which, based on Attorney General Ashcroft's testimony, must be devastating in its analysis of not only this event but of the Gorelick policy — remains classified. And, most significantly, it's likely the Review's criticisms and warnings were either ignored or rejected by the Clinton Justice Department.
So Ashcroft had to know about this investigation when he testified. It's probably one of the reasons he decided to drop the bomb on Gorelick...warning that further shenanigans will not be tolerated.