In the article, I examine the relevance of Just War Doctrine to contemporary conflicts. Just War Doctrine, which grew out of Western Christian thinking, presupposes that evil might be confronted with force, if there is no alternative way to restore a just order. But modern trends call into question the certainty and universality of this doctrine. On the one hand, ideas of moral relativism and comparative justice have become more widespread, potentially undermining the use of the notions “just” and “justified” (...) in relation to military conflicts. On the other hand, the nature of war is changing, as warfare is no longer only kinetic in character. I offer examples of how the evolving character of warfare challenges the traditional understanding of Just War Doctrine. For example, there is the growing threat of cyber warfare, but the ethical criteria for its use are not defined. In relation to Just War Doctrine, questions of whether and when pre-emptive cyber attack is permissible arise, what should constitute legitimate targets of cyber warfare and to what degree collateral damage could be acceptable. Another challenge to the traditional understanding of Just of War Doctrine was the putative doctrine of humanitarian intervention.Prima facie,humanitarian interventions do not comply withius ad bellumcriteria of Just War Doctrine, because of the absence of a direct military threat to the intervening state. The justification of humanitarian intervention is based on the assertion of an intolerable violation of accepted values. The weakness of such approach, as discussed in the article, is that it implicitly assumes that one protagonist’s values are superior to others. A further example of emerging challenges to Just War Doctrine is the phenomenon of hybrid war, a term used to describe a type of conflict that is multi-faceted and in which kinetic warfare is not dominant. The orchestration of several strands of conflict, each designed to be below the threshold to provoke a military response, exploits the absence of legal and ethical norms regulating such activity. I conclude the article by suggesting that, firstly, for Just War Doctrine to remain relevant, it should be expanded to include harms caused by non-kinetic actions, and, secondly, the distinctions between the states of war and peace should be redefined to reflect the changing character of war more accurately. (shrink)