Can war ever be justified? And what, if any, limits should bear on the waging of war? These questions are the stock-in-trade of scholars of just war theory. Hailing from a wide variety of academic disciplines, scholars of just war theory have historically been inclusive when it comes to the kinds of texts that they consider legitimate source-material. Legal treatises, biblical commentaries, political speeches, and military codeshave all been embraced, alongside academic writings on the ethics of war . It comes as some surprise, then, to observe the reticence that some just war theorists have displayed when invited to consider the novels of the Vietnam veteran and celebrated war writer Tim Oâ€™Brien as a body of work worthy of their analysis. Why, this article asks, are just war theorists so afraid of Tim Oâ€™Brien? And what does this tell us about the direction in which contemporary just war theory is moving? The article will argue that the reason just war theorists have been apprehensive about engaging Oâ€™Brienâ€™s work is also the reason why they should read it. This alerts us, it concludes, to the case for (re-)envisioning just war theory in existentialist terms.