The Dilemma of Justification in War

The Christian church has been debating the nature of war. The big philosophical and theological question at hand is that of a just war. We have two camps: realists and pacifists. They say it's not permissible, but practically it is very hard. So you've got a morally way, the good and the bad; then this has to be the last resort. There can't be any less harmful way to go about it.