The just war tradition is a collection of historical views and theories, which eventually developed the just war theory. The just war theory follows a criteria that distinguishes when a country is just to use military action against another country. This theory attempts to protect the innocent and preserve the basic human rights. The criteria which it follows, is meant to examine when the moral decision to use force arises from a conflict of prima facie obligations. The theory operates within a prima facie duty to use force as a last resort in defense of human life and values. When the moral tension arises between these prima facie obligations, they conflict with each other. The just war theory indicates that when the prima facie duty not to injure or kill others can be overridden by another prima facie duty, to act justly and always pursue justice.
According to the just war theory there are two principles which must be followed when a country considers entering a war. The first is the jus ad bellum which defines rules and obligations to be satisfied just before going to war. The first condition states that a country enters a war only if there is a just cause. Mainly, the just causes are protecting innocent life, preserving necessary decent conditions to the humans and also to secure basic human rights. It is justified to defend another nation that is itself the victim of aggression. A war must only be declared by a competent authority entrusted with the common good.