It's said that Russia's response to Georgia's attack on South Ossetia is disproportionate: we hear of "Western leaders anxiously watching for a withdrawal and puzzling over how to punish Moscow for what they called a disproportionate reaction to the Georgian offensive". No one has asked whether a disproportionate reaction or response is always wrong.
War, or an armed attack, can itself be a disproportionate response to some offense. If Britain, for example, declared war on Sweden for producing Abba, that would be disproportionate. It would also be wrong, because Abba isn't cause enough for initiating violence. Britain could at least ask for a large indemnity first. The Nuremberg tribunals placed aggression, a "crime against peace", ahead of war crimes. Perhaps this was meant to remind us that wars usher in far worse than war-fevered cheerleaders suppose, and are virtually always an immoral and disproportionate response to offences...
There is also a relationship between war as an immorally disproportionate response, or starting war for the wrong reasons, and all its consequences. When you start a war for the wrong reasons, you are responsible for all that follows, even the other side's atrocities. Though the other side is to blame for its crimes, so are you. You don't even have the right to kill in self-defense. If you are wrong to start a war, you don't suddenly fall into the right just because, contrary to your expectations, it's you, not the other guy, who has to defend himself.
War is not like self-defense in civilian life, when the response must be proportionate to the threat... The unacceptably disproportionate response was Georgia's in starting the war, not Russia's in finishing it. [More]