Austrian economics says that any organization of individuals will behave along the same lines as an individual would behave, and are subject to the same sorts of incentives, tendencies, and even subject to the same set of natural law.
Let us, then, examine the idea of pre-emptive war using the simplest of examples: a man about to invade his neighbor’s house.
Suppose a man has invaded my property. He is wielding a bazooka, and is pointing it at my house. I might be justifiably concerned. I might hold a gun at the man, yelling at him to put down his bazooka or I will shoot. If he does not put down his bazooka, most would say I am justified in shooting him, in defense of my property, when an imminent threat exists.
Suppose he has not yet invaded my property, but is across the street, threateningly pointing a bazooka at my house? Would I be justified in shooting him then? Most people would again say yes, provided I do not harm any innocent bystanders.
Suppose I have good, solid, hard evidence that he is planning on blowing up my house. Am I justified in going to his house days before the planned attack and shooting him? This is less clear to most people. If I shot his family, that, of course, would be objectionable. But am I justified in invading his property to prevent something I know will happen?
The question is, how can I know? Is it OK to punish someone before the attack takes place, before an act of violence is an imminent threat? The problem here is that we cannot know the future. We cannot know with any certainty what an individual will end up doing, regardless of their current plans. Intent does not always (for some, rarely) leads to action, and is therefore not equivalent to action. Even if action has begun (he purchased a bazooka online from his favorite online bazooka merchant), who knows whether that action will be completed, or even what end that action will follow to?
At what point are we justified in attacking the attacker to defend ourselves? I would say that the only time we are justified is when the threat is imminent. By imminent I mean he is holding a gun or wielding a knife or threatening us with a bomb. Planning something days or weeks from now is not imminent, and so to attack someone three weeks before the planned attack would be akin to premeditated murder, or at least manslaughter.
I’m not equating military action with murder. But I am suggesting that the same sorts of rules apply: how can we know intentions? How can we know for absolute certain that a country poses an imminent threat? Is attacking them preemptively even the best option to secure our safety? (Consider, for instance, the Cuban Missile Crisis, a very tense stand-off that ended, thankfully, with disarmament as a result of talking.) There are so many problematic aspects from a logisitical, ethical, and moral standpoint that I hardly know where to begin.
Suffice it to say that a policy of preemptive aggression, including preemptive war (attacking them over there, or attacking them before they attack us) turns our moral and ethical compass on its head. If we are justified in preemptively attacking Iran as they are supposedly interested in developing nuclear weapons, are they then justified in attacking us first as a result of our tens of thousands of nuclear weapons, a military orders of magnitude larger and more sophisticated, and a history of an antagonistic attitude towards Iran? This policy of preemption leads to an endless barrage of these type of moral quandries.
We should, without reservation, repudiate preemptive aggression completely, and instead call it for what it is: an immoral and unjustified tactic under any circumstance.