The claim by the United States to a right of what has come to be known as “preemptive selfdefense” has provoked deep anxiety and soul-searching among the members of the college of international lawyers. Some have feared that the claim signaled a demand for the prospective legitimation of “Pearl Harbor” types of actions, that is, sudden, massive, and destructive military actions “out of the blue,” by one state against another in the absence of a state of war, with the objective of militarily neutralizing or even eliminating a latent or potential adversary. Since some public intellectuals within the American political system had recommended such a strategy with respect to the People’s Republic of China in the midst of the Cold War, the anxiety could not be dismissed as entirely unfounded or even hysterical. Nor could it be ignored as if it were some sort of exclusively American aberration that could be tolerated as the idiosyncrasy of one state. From the earliest unilateral claims to a continental shelf, a copycat or mimetic dynamic in modern international law has taken shape whenever an enhancement of state power has become available, so that the possibility of similar claims to an expanded notion of preemptive self-defense by many other states could not be excluded. Indeed, while the United States may now have retreated somewhat from its 2002 broad claim to preemption, various other states (including some with nuclear weapons) have adopted the preemptive self-defense claim as their own. If the U.S. claim posed potentially destabilizing consequences for world order, how much more so would proliferation of the claim?