Overall, jus in bello suggests in wars, harm can only be used against combatants, never against the innocent. But in the end, the aim is to establish peace and security within the commonwealth. As Vittola’s conclusion: ‘the pursuit of justice for which he fights and the defence of his homeland’ is what nations should be fighting for in wars (Begby et al (2006b), Page 332). Thus, although today’s world has developed, we can see not much different from the modernist accounts on warfare and the traditionists, giving another section of the theory of the just war. Nevertheless, we can still conclude that there cannot be one definitive theory of the just war theory because of its normativity.

Jus post bellum

Finally, jus post bellum suggests that the actions we should take after a war (Frowe (2010), Page 208).
Firstly, Vittola argues after a war, it is the responsibility of the leader to judge what to do with the enemy (Begby et al (2006b), Page 332).. Again, proportionality is emphasised. For example, the Versailles treaty imposed after the First World War is questionably too harsh, as it was not all Germany’s fault for the war. This is supported by Frowe, who expresses two views in jus post bellum: Minimalism and Maximalism, which are very differing views. Minimalists suggest a more lenient approach while maximalist, supporting the above example, provides a harsher approach, punishing the enemy both economically and politically (Frowe (2010), Page 208). At the last instance, however, the aim of war is to establish peace security, so whatever needs to be done can be morally justified, if it follows the rules of jus ad bellum.
In conclusion, just war theory is very contestable and can argue in different ways. However, the establishment of a just peace is crucial, making all war type situation to have different ways of approaching (Frowe (2010), Page 227). Nevertheless, the just war theory comprises of jus ad bellum, jus in bello and jus post bellum, and it can be either morally controversial or justifiable depending on the proportionality of the circumstance. Therefore, there cannot be one definitive theory of the just war but only a theoretical guide to show how wars should be fought, showing normativity in its account, which answers the question to what a just war theory is.