Amperage, et. al.
There are a few things that I think may aid you in your search for an answer as to whether or not there is any moral justification to preemptively attack. One of the prevalent theories that I can think of is just war theory
. Within just war theory, there are two defining categories, justice for war (just ad bellum) and justice in war (jus as bello). Jus ad bellum
determines the just reasons before
a war begins. Think of it basically as a list of criteria a certain country would have to meet in order to declare war on another country. Within this concept, there are issues of sovereignty, rights, obligations, etc. For example, a war may be undertaken if it is; undertaken by a legitimate authority, waged for a just cause, waged as a last resort, rely on a declaration of war, and the chances of success are more than reasonable.
Of course, once one enters into this issue, then the consequent of just ad bello takes effect
. Jus in bello
determines the just methods during
war. Think of it as a list of things opponents can or cannot do during the conflict, like the Geneva Convention treaty. Within this concept, there are issues such as asymmetric warfare (guerilla warfare), heavy, biological, nuclear, etc. weapons usage, etc. But I think as far as your question is concerned, what you want is an examination of the subtleties of jus ad bellum (justice for war). What I think is at the crux of your question is the validity of aggression and the consequences that follow. On that note, jus ad bellum possess an especially integral notion, which is that a war is just if it is in response to aggression. This is the trick though, especially in its application to a preemptive attack.
Who is really the aggressor in a preemptive attack?
Jus ad bellum would dictate that if a legitimate authority has just cause, has exhausted all means of recourse, and has a reasonable chance of winning, they are fully justified in engage in a preemptive attack. But the aggressor must be established. I think many of us could think of wars, either in the past ten years, hundred years, or even few thousand years of wars that base themselves on the principle of labeling an aggressor as an aggressor and conforming to the rubric of just war theory.
So the source of aggression becomes the scale to which an attack is justified.
Aggression does not have to be a physical form, like one country attacking another, one person attacking another. It could be in a form like economic threats, such as one country doing something which collapses another economy, etc. But suppose you had one country that had the ability to virtually ruin your countries economy. Does that country have the right to preemptively attack the country that may be able to ruin the other country? This is a huge
issue that is still hotly debated. As a remedy to this, the US (and I would suppose other countries as well) have laws advocating seizure of foreign property in the event of war. Both countries would lose substantially if the other were attacked, a form of mutually assure economic destruction. In some ways is actually quite brilliant in the respect that as the countries of the world tie together more and more, an attack made on one country ruins basically everyone else, so in theory, no one would dare war on another. But that in itself is like putting all the eggs in one basket and we see the negative effects of this in the global economy today.
So an answer that I could conclude based on these arguments are that it is acceptable to launch a preemptive attack on another.
However, it is acceptable under the terms that follow the same lines as just war theory and that there has to be some clear form of aggression which validates the preemptive attack. That form of aggression does not have to be physical, but has to be justified as being such.