This interview was conducted March 20, 2002. Clarke was still working for the White House.
"By the time 1998 the embassy bombings occurred, I think everyone in the Clinton Cabinet would have said that Al Qaeda is a serious threat. In fact, if you look in retrospect at what the Clinton administration did after those embassy bombings through to the end of that administration -- since now most of it is public knowledge, lot of it was highly classified at the time -- if 9/11 had not happened, most Americans looking at what the Clinton administration did about bin Laden would have said, 'What an overreaction. Why were they so preoccupied with bin Laden?'
There was an enormous amount of activity that was carried on if you look at the predicate, prior to the attack on the Cole destroyer in October 2000. The predicate was Americans killed at two embassies in Africa. Yet there was this massive program that was initiated to go after bin Laden. It didn't succeed, but it tried very hard. It did prevent some attacks, and it delayed others. But looked at in vacuum, the Clinton administration activities, 1998 to the end of the administration against bin Laden -- if you look at that without knowing in advance that 9/11 is going to happen, if you can separate that in your mind, the Clinton administration activities against bin Laden were massive."
ON EDIT:
http://www.pbs.org/wgbh/pages/frontline/shows/knew/interviews/clarke.html