I have always understood the Just War criteria in a personal way, not justly applied to others. In
neploho’s example the oppressed Christians have the right to defend themselves from the non-Christian agressors much in the manner that Christ said to buy swords.
The fact He said two swords were enough indicates to me there is a legitimate line to self defense whether it is to protect oneself from wild animals or an unjust attacker while doing Gods work, but not permission to use those swords to bring justice to others. The many examples of offering the other cheek when struck unjustly, giving your cloak in addition the shirt you are being sued for, or paying to the non-religious government in authority (legitimate or non-legitimate) over you the (unjust/just) dues/taxes set against them.
Nothing in the Gospels suggests we can or should transfer that ‘right of protection’ to others, or exceed the limits of the two greatest Commandments. The homeowner is warned to stay alert inside his home in case the theif should try and rob him, not urged to leave the safety of his home to search the neighborhood for the thief to exact justice before the crime is committed. Nothing suggests to me a stronger Christian neighbor should do the search and destroy of the non-Christian agressor for the weaker Christian neighbor either.
This: “legitimacy belongs to the prudential judgment” is worthy of further debate. For a Christian (Catholic specifically) I think we should apply a theological legitimacy to the authority when determining if going to war for others meets the Just War criteria. America was not directly threatened by North Koreans, North Vietnamese, Iraqis invading Kuwait 1991, or the conflict in Bosnia as examples yet we went to war to protect the oppressed. Noble, sure but is it Just, I think no.
I am not suggetsing we sit by and do nothing when one group tries to wipe out another group be they Christain or non-Christian for the many reasons they do it, but if we as a nation do decide to go to war using the Christian Just War criteria it is dangerous and hypocritical to not impliment a Christian ethic once we complete that war unlike what we have done in the last two wars leaving in place the un-Christian ideology that is the root behind the agression to begin with. Then again, going to war to instill the Christian ethic (or secular democracy) does not seem to agree with the ideology which seems best represented by
Luke 9:54-56 .