The aggression involved in war is at odds with basic values of civilization. It attacks people’s rights to life, security, subsistence, peace and liberty. However, just war theory claims that war can, under certain conditions, be morally justified. Pacifism argues that war is never morally justified. Realism says that moral concepts cannot be applied to questions of war (or foreign policy generally).
Just war theory divides into three parts:
1 jus ad bellum – the justice of resorting to war;
2 jus in bello – just conduct in war;
3 jus post bellum – justice at the end of war.