Preemption comes in many forms and what we think of it depends on the circumstances. One state may not strike another merely because the second might someday develop an ability and desire to attack it. Yet few would criticize a strike in the midst of an ongoing war against a second state’s program to develop new types of weapons. Between these two examples lie countless fact patterns.
In the end, each use offeree must find legitimacy in the facts and circumstances that the state believes have made it necessary. Each should be judged not on abstract concepts, but on the particular events that gave rise to it. While nations must not use preemption as a pretext for aggression, to be for or against preemption in the abstract is a mistake. The use of force preemptively is sometimes lawful and sometimes not.