Did Bill Clinton state that we could pre-emptively, unilaterally take action against any regime that harbored terrorists?
No but he did launch a ton of missiles aimed at Iraq.
On December 16, 1998, President Bill Clinton mandated Operation Desert Fox, a major four-day bombing campaign on Iraqi targets.
President Clinton stated in February 1998:
Iraq admitted, among other things, an offensive biological warfare capability, notably, 5,000 gallons of botulinum, which causes botulism; 2,000 gallons of anthrax; 25 biological-filled Scud warheads; and 157 aerial bombs. And I might say UNSCOM inspectors believe that Iraq has actually greatly understated its production.... Over the past few months, as [the weapons inspectors] have come closer and closer to rooting out Iraq's remaining nuclear capacity, Saddam has undertaken yet another gambit to thwart their ambitions by imposing debilitating conditions on the inspectors and declaring key sites which have still not been inspected off limits.... It is obvious that there is an attempt here, based on the whole history of this operation since 1991, to protect whatever remains of his capacity to produce weapons of mass destruction, the missiles to deliver them, and the feed stocks necessary to produce them. The UNSCOM inspectors believe that Iraq still has stockpiles of chemical and biological munitions, a small force of Scud-type missiles, and the capacity to restart quickly its production program and build many, many more weapons.... Now, let's imagine the future. What if he fails to comply and we fail to act, or we take some ambiguous third route, which gives him yet more opportunities to develop this program of weapons of mass destruction and continue to press for the release of the sanctions and continue to ignore the solemn commitments that he made? Well, he will conclude that the international community has lost its will. He will then conclude that he can go right on and do more to rebuild an arsenal of devastating destruction. And some day, some way, I guarantee you he'll use the arsenal.... President Clinton ~ 1998 [5]
http://en.wikipedia.org/wiki/Iraq_Liberation_Act