“On June 1, 2002, [President] Bush made a comprehensive effort to delineate a rationale for a war [against Iraq] to the graduating class at West Point. If an adversary provided weapons of mass destruction to a terrorist group, the U.S. might be attacked but might not ever know who sponsored the blow. Deterrence–essentially, the threat of devastating retaliation–would not forestall the attack, since the source of the weapons of mass destruction might never be known. The only way to guard against the threat would be to eliminate the weapons of mass destruction at their source. Nor would the United States wait too long before it acted. The president noted that the traditional notion of preemption held that a nation would be justified in striking first if an adversary began to make discernible war preparations and began to move its ships, ready its planes, or mobilize its troops. But that, Bush argued, would not work in the post-9/11 world. If the United States waited for threats to materialize, Bush said, it would have waited too long. It was not so much a doctrine of preemptive as preventive war.”
– Michael R. Gordon and Bernard E. Trainor, Cobra II, Page 72