Responses to President Trump’s Ukraine gambit have been interesting to say the least.  Russia hawks are aghast at the idea of trying to normalize relations with Russia while the MAGA-aligned crowd is ready to cut off American support for Ukraine completely. America’s Ukraine policy is becoming something of a litmus test within Jacksonian America to determine the degree to which someone supports the President. Perhaps counterintuitively, I believe the Trump administration’s handling of the Ukraine war, despite the messy Oval Office moment (and it was only a moment), is more aligned with the finer points of just war theory and Christian realism than many are willing to consider.

In assessing the President’s attempt to kick-start peace talks on Ukraine, our ability to leverage the moral framework of just war theory to consider a pathway to peace constitutes the first major test of just statecraft as an analytical and pedagogical framework.

Just War is the Easy Argument on Ukraine

The justness of the Ukrainian cause is beyond dispute. Russia is clearly the aggressor, is clearly violating international law, and undoubtedly shoulders the blame for its own suffering. However, justifying the war and its prosecution on moral grounds is only one part of the just war equation. In this particular case, it’s the easiest part of the argument to make, and many have been comfortable to stay there.

But buried under the moral justifications for the Ukrainian cause and to continued American military aid by extension lies an uncomfortable truth that just war theory demands we address: The righteousness of the cause does not guarantee victory. Even in a best-case scenario, full justice may prove elusive. Indeed, for the many who have lost loved ones, justice may never be complete in this world.

In a world bereft of a just God, this would indeed be tragic. In a world where the justice of God is both watchful and sure, however, we can receive both comfort and calling: Comfort that God’s justice will prevail, and a calling to be free of the need to mete out vengeance and achieve a perfect justice in the present.

Yet it is precisely the moral clarity of the Ukrainian conflict that has made proponents of maintaining US support ambivalent towards articulating an end to the war, namely, an ordered peace to use St. Augustine’s framing. The lack of a clear theory of victory coupled with an overreliance on President Zelensky’s assessments of the war have led to a moralizing posture towards Russia that is ahistorical and lacking in clear-sightedness when it comes to objectively assessing the feasibility of Ukraine’s stated war aims. Wisdom is hard to find under normal circumstances, but in this fog of war, it appears to be MIA.

Probability of Success, on the Other Hand…

What’s missing in much of the just war-based justifications of American support for Ukraine’s war effort is a critical element of just war theory. Namely, that engagement in a just war requires a reasonable chance of success. This probability principle recognizes that ends don’t always justify means and that even the prosecution of a just war can become unjust if it unnecessarily prolongs suffering. Further, the probability principle implicitly acknowledges a just war can be lost.

In Question 40 of his Summa Theologica, St. Thomas Aquinas outlines his framework for just war, but notes that “we wage war in order to achieve peace.” He doesn’t detail what a just peace necessarily entails, but to the degree that a war is just insofar as it defends the good while punishing and restraining evil, then a just peace would be, at least in general terms, a reasonable reestablishment of a status quo ante bellum.

Following Aquinas, Grotius writes in Book II.24.9 of Law of War and Peace that only wars that are both moral in cause and adequately resourced to provide a maximal chance of success are worth fighting. For Grotius, the limits of men and materiel are critical in the prudential aspect of choosing to engage in a just war. While Aquinas considers the morality of war, Grotius considers the critical variables in determining when warfighting is practical. This is a particularly relevant consideration for the US in its role as an international guarantor of security.

In this sense, Jesus’ brief metaphor of a warring, yet diplomatic, king in Luke 14:31-32 anticipates both the morality and wisdom (prudential) components of what would become just war theory. Indeed, Jesus and Grotius both appear less concerned with a war’s outcome (greatest of the unknown unknowns) than with the ability of an individual to rightly judge the cost of the undertaking.

This is precisely the point we appear to be at with Ukraine, and what President Trump is trying to convey to both Ukraine and Russia. Yet American and European backers of Ukraine, along with President Zelensky, don’t appear interested in this fact. Due to such a grave oversight, I believe that President Trump’s efforts to get Ukraine and Russia to the negotiating table should be supported as well within the bounds of Christian realism and just war theory.

Are We There Yet?

President Trump and his team appear to have assessed the current status of the war and concluded that the conflict is at that point where further fighting, given available men and materiel, allows neither Ukraine nor Russia to achieve their maximum war aims. To continue the war is to engage in sunk-cost thinking, prolong needless suffering, and risk compounding injustices. That Zelensky and Putin don’t appear to have reached the same conclusion doesn’t mean Trump is under any obligation to wait for them to continue expending blood and (American) treasure.

Rather, Trump must consider, as an involved and responsible belligerent, the part he can play in winding this conflict down. The limited aid given to Ukraine under the Obama and the first Trump presidencies was not enough to achieve the goal of deterring Putin. Then, after February 2022, the massive, over 100 billion dollars in aid sent to Ukraine under Biden also failed at its goal of decisively turning the tide against Russia. It’s fair for Trump to wonder when the end will be in sight, with many knowledgeable observers asking the same question.

Give Peace a Chance

We cannot be serious about Christian realism, just war, or just statecraft if it only commits us to an open ended, uncritical support of Ukraine with total victory as the only acceptable outcome. That’s neither Christian, nor realist, nor just. It’s only a justification for war. Forever.