I saw a question on a Progressive website that requires an Agree, Leaning Agree, Leaning Disagree or Disagree that went like this: Pre-emptive Wars are by their nature "unjust wars". Ergo, Iraq is an "unjust war". The responses were:33%, 17%, 6% and 44%! Granted there were only a few responses, but it begs the question, does anyone out there know the definition of the term "Just War"?
I decided to go surfing and find some common definitions. Although, I'm an extremely wary Wikipedia user, they actually have very comprehensive definitions, history and explanations of Just War Theory:
and Jus in bello/Jus ad bello: http://en.wikipedia.org/wiki/Jus_in_bello
The concepts of a Just War didn't just pop up as an answer to Bush's new fangled term "Pre-emptive War". They have been debated and set out and agreed upon through out the course of all human history.
In modern language, these rules hold that to be just, a war must meet the following criteria before the use of force (Jus ad bellum):
Just Cause: Force may be used only to correct a grave public evil (e.g. a massive violation of the basic rights of whole populations) or in defense;
Comparative Justice: While there may be rights and wrongs on all sides of a conflict, to override the presumption against the use of force, the injustice suffered by one party must significantly outweigh that suffered by the other;
Legitimate Authority: Only duly constituted public authorities may use deadly force or wage war;
Right Intention: Force may be used only in a truly just cause and solely for that purpose- correcting a suffered wrong is considered a right intention, while material gain is not.
Probability of Success: Arms may not be used in a futile cause or in a case where disproportionate measures are required to achieve success;
Proportionality: The overall destruction expected from the use of force must be outweighed by the good to be achieved.
Last Resort: Force may be used only after all peaceful and viable alternatives have been seriously tried and exhausted.
Note that these are only the most typical conditions cited by just war theorists; some (such as Brian Orend) omit Comparative Justice, seeing it as fertile ground for exploitation by bellicose regimes.
Conducting a Just War (Jus in Bello)
Once war has begun, Just War theory also directs how combatants are to act:(Jus in bello)
Just War conduct should be governed by the principle of discrimination. The acts of war should be directed towards the inflictors of the wrong, and not towards civilians caught in circumstances they did not create. The prohibited acts include bombing civilian residential areas that include no military target and committing acts of terrorism or reprisal against ordinary civilians. Some believe that this rule forbids weapons of mass destruction of any kind, for any reason (such as the use of an atomic bomb).
Just War conduct should be governed by the principle of proportionality. The force used must be proportional to the wrong endured, and to the possible good that may come. The more disproportional the number of collateral civilian deaths, the more suspect will be the sincerity of a belligerent nation's claim to justness of a war it initiated.
Just War conduct should be governed by the principle of minimum force. A certain amount of force must not be used if a lesser amount of force would accomplish the same goals. This principle is meant to limit excessive and unnecessary death and destruction. It is different from proportionality because the amount of force proportionate to the goal of the mission might exceed the amount of force necessary to accomplish that mission.
Torture, of combatants or non-combatants, is forbidden.
Prisoners of war must be treated respectfully.
Many throughout history have considered conscription an unjust means, e.g.
"It is debasing human dignity to force men to give up their life, or to inflict death against their will, or without conviction as to the justice of their action." -- Albert Einstein, Mahatma Gandhi in the Manifesto Against Conscription and the Military System 
Ending A War: Jus Post Bellum
In recent years, some theorists have proposed a third category within Just War theory. Jus post bellum concerns the regulation of the process of terminating war, and the transition from war to peace. One of the main proponents of jus post bellum is Brian Orend, who proposes the following rules:
Just cause for termination - A state may terminate a war if there has been a reasonable vindication of the rights that were violated in the first place, and if the aggressor is willing to negotiate the terms of surrender. These terms of surrender include a formal apology, compensations, war crimes trials and perhaps rehabilitation.
Right intention - A state must only terminate a war under the conditions agreed upon in the above criteria. Revenge is not permitted. The victor state must also be willing to apply the same level of objectivity and investigation into any war crimes its armed forces may have committed.
Public declaration and authority - The terms of peace must be made by a legitimate authority, and the terms must be accepted by a legitimate authority.
Discrimination - The victor state is to differentiate between political and military leaders, and combatants and civilians. Punitive measures are to be limited to those directly responsible for the conflict.
Proportionality - Any terms of surrender must be proportional to the rights that were initially violated. Draconian measures, absolutionist crusades and any attempt at denying the surrendered country the right to participate in the world community are not permitted.
Challenging Just War theory
There have been several theories that have challenged Just War theory. Also, some have claimed the Just War theory is impractical in real-war situations.
Realism - The core proposition of realism is a skepticism as to whether moral concepts such as justice can be applied to the conduct of international affairs. Proponents of realism believe that moral concepts should never prescribe, nor circumscribe, a state's behaviour. Instead, a state should place an emphasis on state security and self-interest. One form of realism - descriptive realism - proposes that states cannot act morally, while another form - prescriptive realism - argues that the motivating factor for a state is self-interest.
Pacifism - Pacifism is the belief that war of any kind is morally unjust. One argument pacifists have made against Just War theory is that Just War theory advocates the protection and sanctity of innocent lives, yet during war the lives of innocents cannot be guaranteed. Therefore, unless the lives of innocents can be guaranteed, war cannot be justified under any grounds.
"Just" Wars that violate Just Wars principles. Many ideologies agree with the tradition that war should be fought only if done for a just cause but reject most if not all of the other criteria of the tradition. The Marxist tradition can be seen as part of this category. For Marxists the only criteria is whether a war is "progressive" (ie just within their terms) and it is irrelevant how costly the war may be. Husayn bin Ali is celebrated for his pursuit of his "just" claim to the caliphate despite the fact his rebellion was doomed to failure. However Husayn's rebelion was an unjust war by the criteria of the Just War tradition because it violated the principle that there must be a reasonable chance of success.
Absolutism - Absolutism holds that there are various ethical rules that are, as the name implies, absolute. Breaking such moral rules is never legitimate and therefore is always unjustifiable. The philosopher Thomas Nagel is a well known supporter of this view, having defended it in his essay War and Massacre.
Militarism - Militarism refers to the belief by some that war is not inherently bad, but rather can be a beneficial aspect of society. This theory does not hold much traction among many mainstream theorists, however.
Revolution and Civil War - Just War Theory states that a just war must have just authority. To the extent that this is interpreted as a legitimate government this leaves little room for revolutionary war or civil war, in which an illegitimate entity may declare war for reasons that fit the remaining criteria of Just War Theory. This is not a problem if the "just authority" is interpeted more widely such as "the will of the people" or similar.
Based on this information, and the information on how we got into this war, have managed it and see no end to it in sight, there is absolutely NO justification for this war under any circumstances. This is why I felt a primer was a pretty good idea...
Some other Just War Links: http://www.mtholyoke.edu/acad/intrel/pol116/justwar.htm
According to this monk, the term War on Terror is a complete misnomer, it doesn't even come close to the definition!