From a Buddhist perspective can you ever say there is a "just war"?
My personal opinion is that no, there is no such thing as a "just war". I suppose I consider myself an advocate of ahimsa
For a moment let us look at the Sangama sutta where we see this remark from the Buddha:Winning gives birth to hostility. Losing, one lies down in pain. The calmed lie down with ease, having set winning & losing aside. http://www.accesstoinsight.org/tipitaka ... .than.html
The Blessed One later states:
A man may plunder as long as it serves his ends, but when others are plundered, he who has plundered gets plundered in turn. A fool thinks, 'Now's my chance,' as long as his evil has yet to ripen. But when it ripens, the fool falls into pain. Killing, you gain your killer. Conquering, you gain one who will conquer you; insulting, insult; harassing, harassment. And so, through the cycle of action, he who has plundered gets plundered in turn. http://www.accesstoinsight.org/tipitaka ... .than.html
I think the later statement summarizes the line of thought quite well: harass and you will be harassed, assault and you will be assaulted.
However, what about fighting as a means to an end? Can you fight out of compassion?
The Yogâcāra-bhūmi-śāstra does state that if a Bodhisattva in an extreme situation sees a person about to commit a crime that will drive them into Avici Hell and out of pure compassion and without malice kills the perpetrator, there is no violation of precepts and furthermore merit is actually acquired.
《瑜伽師地論》卷41〈10戒品〉：「謂如菩薩見劫盜賊為貪財故欲殺多生。或復欲害大德聲聞獨覺菩薩。或復欲造多無間業。見是事已發心思惟。我若斷彼惡眾生命墮那落迦。如其不斷。無間業成當受大苦。我寧殺彼墮那落迦。終不令其受無間苦。如是菩薩意樂思惟。於彼眾生或以善心或無記心。知此事已為當來故深生慚愧。以憐愍心而斷彼命。由是因緣於菩薩戒無所違犯生多功德。」(CBETA, T30, no. 1579, p. 517, b8-17)
So, in an extreme situation where for example someone might seek to kill an Arhat, if the Bodhisattva kills that person they prevent them from falling into Avici Hell. However, the text stresses that it is done with deep shame and compassion -- there is no malice, hatred or anger.
At least according to this text, there are extreme situations where killing can actually be deemed compassionate. However, I would stress here that this is in the case of a Bodhisattva who is presumably already quite advanced and will not experience malice or anger. This doesn't include organized warfare where anonymous people are exchanging gunfire under the banners of various nation states.
Theory aside, however, how about recent history?
I used to think that WWII was a just war for the Allies. After all, the Nazis and Imperial Japanese were brutal and committed horrific acts of murder.
Still, when you look at it from the bigger picture, it didn't solve anything. As the Buddha outlined above: "Killing, you gain your killer."
Yes, Germany and Italy were pacified and the risk of warfare in western Europe breaking out can be ruled out. Yes, Japan was pacified and adopted a pacifist constitution. However, the problems just shifted elsewhere. With the fall of Germany, the stage was set for the the cold war which claimed millions of lives. The Japanese were sent packing home, but then in East Asia the stage was set for Mao, Khmer rouge, the Kim family in North Korea and the Vietnam War. I think more civilians died under Mao and Stalin than there were casualties in WWII.
Nothing was ever solved. Problems just shifted elsewhere. The fallen dead are reborn and the process continues. The cycle of violence only perpetuates itself. No matter how many bad guys you kill, there will be many more to come.
Violence never really resolves anything. Thus why I'm a proponent of ahimsa