How Ukraine’s Just War Challenges Just Peace Theory

Introduction

In recent years a remarkable shift from the theory of just war to the theory of just peace can be observed among theologians of various religious traditions but especially within Christianity (Latiff 2018, 72). The just war theory has received severe critique based on the assumption that interstate conflict belongs to the past and that twenty-first-century conflicts mainly take place within states themselves (Cahill 2019, 169). This assumption, however, is seriously challenged by the 2022 Russian invasion of Ukraine and the ensuing conflict, which show that the theory of just war is still valid in the twenty-first century in order to guarantee state security. The assumption that conflicts take place mainly within states themselves is untenable. The war in Ukraine raises the question whether the theory of just peace is practically applicable to ensure the security of the state of Ukraine and its people.

This article aims primarily to demonstrate that the just peace theory fails in at least four ways when applied to the Ukraine war. First, just peace theory is based upon international cooperation of states through the United Nations. This structure has shown itself incapable of safeguarding Ukraine’s security. Second, the just peace theory does not provide sufficient arguments for the necessary Ukrainian counterattacks and attacks on Russian soil. Third, the just peace theory focuses on individual human rights and tends to forget the right of nations. In the defense of Ukraine, the nation still plays an important role. Fourth, just peace theory fails to provide a moral framework for the soldiers who need to fight wars. This is confirmed by Christian military officers and is closely related to the underlying anthropology of just peace theory, which is highly problematic from a classical Augustinian perspective. This article therefore also challenges the underlying theological anthropology that theologians have developed in their replacement of just war theory with just peace theory.

This article deals with these four points by first of all explaining the shift to just peace theory among Christian theologians. The question is raised whether the just peace theory actually can help Ukraine and Ukrainian citizens. After explaining the content of just peace theory, this theory is applied to the Ukraine war in which the failures of the theory will be discussed. The article ends with the search for a new variant of the just war theory in which the positive elements of the just peace theory, such as jus post bellum, are integrated into and brought into dialogue with the just war theory.

The Shift to Just Peace Theory

In April 2016 eighty-five theologians, priests, and experts from more than thirty different countries gathered in Rome for the Nonviolence and Just Peace Conference to discuss the theory of just war and formulate an alternative theory (Stephan 2016). The conference concluded with a unanimous statement to reject the theory of just war (McCarthy 2016). The contributions to the conference were published in the book Choosing Peace, in which contributors argued that just war fails to explain why wars happen in the first place and how wars can be prevented by developing a constructive peace framework (Dennis 2018).

This rejection of just war should be understood from a longer development in which the traditional theory of just war has come under severe pressure. Already in the 1980s, a group of Christian scholars in the United States criticized the theory of just war (Thistlethwaite and Stassen 2008). In 2003 then-Cardinal Ratzinger stated in an interview that “given the new weapons that make possible destructions that go beyond the combatant groups, today we should be asking ourselves if it is still licit to admit the very existence of a just war” (Ratzinger 2003).

Since the 1990s a new paradigm of just peacemaking has emerged as an alternative (Stassen 1992). The just peace theory has been defended by Christian scholars because, according to them, it is particularly strong in political reconciliation and in reestablishing justice through restoring right relations. In Just and Unjust Peace, Daniel Philpott, for example, developed his version of just peace theory with an emphasis on reconciliation by broadening the concept of justice and placing it on Christian foundations (Philpott 2012).

Although Christian scholars have strongly promoted just peace theory, the support for the theory is much broader. Jewish and Muslim scholars have also embraced this theory. For instance, in 2008 a group of Jewish, Christian, and Muslim scholars published a joint statement on just peace as an alternative to just war (Thistlethwaite and Stassen 2008). It is not surprising that just peace theory receives support from these religious traditions. According to Philpott, a religious concept of justice is particularly strong because religions such as Judaism, Christianity, and Islam already have centuries-old traditions and experiences with reconciliation practices (Philpott 2012, 99).

In recent decades, the theory of just peace has developed significantly, partially boosted by the end of the Cold War. The United Nations has worked to prevent and condition war through the Security Council. Furthermore, the Cold War, the Vietnam War, and nuclear armament led to a revival of just peace theory (Walzer 2015). A Catholic contribution to the just war theory in the context of nuclear armament can be found in Thomas Merton’s Peace in the Post-Christian Era, where he defends elements of just war theory in line with papal encyclicals but, at the same time, defends the quest for peace and nuclear disarmament (Merton 2004, 140–51). This corresponds to the expansion of the field of peace history during the early to mid-1960s (Peterson et al. 2023, 20). The optimism of a peaceful dialogue between nations through international organizations like the United Nations contributed to this trend. Although in the English-speaking world the theory of just war remained dominant, a debate on the theory of just peace has now begun in the United States (Lienemann 2018, 37).

Several churches and theologians in particular have played an important role in promoting the theory of just peace. For instance, the German Evangelical Churches and the German Roman Catholic bishops have made efforts to introduce the theory of just peace into international law (Evangelische Kirche in Deutschland 2007). The World Council of Churches has repeatedly proposed to replace the theory of just war with a theory of just peace. In the meantime, the shift to just peace theory has also been supported by Pope Francis, who has dedicated his papacy to support nonviolence and the call for peace. In his message on World Day of Peace 2017 he reflected on “nonviolence as a style of politics for peace” (Francis 2017). The conference of Catholic theologians in April 2016 resulted in a joint call to no longer use or teach the just war theory. Instead, a theory of just peace and nonviolence should be promoted by the church.

The full-scale Russian invasion of Ukraine on February 24, 2022, has raised fundamental questions about the applicability of just peace theory. However important it is to talk about a more peaceful world, the ongoing war in Ukraine teaches the world that war will remain a relevant factor in the twenty-first century. The war in Ukraine raises the question how the necessary defense and ongoing counteroffensive by Ukraine can be justified in the context of the newly proclaimed just peace theory. Can just peace theory provide justification for Ukraine’s self-defense?

Understanding Just Peace Theory

In order to answer this question, it is necessary to understand just peace theory. The theory seeks to find a middle way between nonviolence and just war (Love 2018, 60–71). The theory claims to be applicable in times of both peace and conflict, and it seeks to bring about long-term peace. Although many scholars in the field of international relations understand peace as the end of war, the concept of peace in just peace theory contains substantially more (Peterson et al. 2023, 4). For example, the Oxford Handbook of Peace History distinguishes positive peace from negative peace: “The concept of positive peace provides a framework to connect peace to domestic order, human improvement and happiness” (Peterson et al. 2023, 4). Just peace therefore contains a number of conditions, such as “addressing issues of guilt and compensation, the quality of new domestic and international relationships, the issues of justice and human rights and it implies measures to prevent new conflicts” (Boer 2008, 81). Furthermore, the UN has pointed to dialogue and the economic aspect of a just peace: “Peace is not only the absence of conflict but also requires a positive, dynamic participatory process where dialogue is encouraged and conflicts are solved in a spirit of mutual understanding and cooperation, and socioeconomic development is ensured” (United Nations Human Rights Council 2016).

Three Forms of Just Peace

In current literature on just peace theory, three main forms of just peace can be distinguished: (1) just peace in the context of just war, (2) just peace through peacekeeping operations, and (3) just peace understood as reconciliation (Stahn 2020, 5).

The first form of just peace is the most basic version. In this form, peace is mainly defined as the absence of conflict. Hence, it is the ultimate goal for which a war is waged. It thus adopts a delineated concept of peace that is mainly concerned with settling the ongoing conflict and treating the defeated in a just and humane way. This variant does not specify how peace can be sustainably achieved and according to which positive conditions peace should be established. Because just peace is developed in the context of just war, the emphasis lies on the way violence is exercised and ended, whereas the theory of just peace is much broader and contains a more comprehensive concept of peace.

This broader concept is reflected in the second form: just peace through peacekeeping operations. This form does not start from a situation of war but of peace. It states that war is an exception that should be made virtually impossible. Here peace is defined positively through a set of conditions, such as social, economic, and political institutions, which should promote dialogue and rule out violence. The criticism of this theory is that the international institutions operate mainly from a Western and liberal paradigm. Just peace through peacekeeping operations, therefore, has a liberal and a universal variant. In the liberal variant, the starting point is an individual perspective on human beings with corresponding individual human rights. These human rights have to be protected by international organizations like the United Nations. In the universal variant, the emphasis is much more on parties listening to one another and on understanding the local context and culture within which sustainable peace must be built. Although the universal variant operates from a fundamentally different starting point, both forms look primarily at prevention rather than remediation after a conflict.

Finally, there is just peace that focuses on reconciliation between conflicting parties and the restoration of justice by guaranteeing human rights. The rights of victims and the search for truth through dialogue play an important role in this form. Through the process of truth-seeking and reconciliation, a purification can take place on which a lasting peace can be built. This variant stresses learning lessons from the past to prevent future conflict. A good example of the application of this variant of just peace is the Truth and Reconciliation Commission in South Africa (Tutu and Tutu 2014, 5–6). Besides the search for truth through dialogue, important elements of this theory also include reparation, restoration, and forgiveness.

Criticisms of Just Peace Theory

In the different forms of just peace, military deployment is drastically limited by international agreements and international coordination through the United Nations (Kaldor 2008, 36). We will see that this specific element has major consequences for the Ukraine war. In a theory of just peace, it is impossible to wage war against other states, and military deployment is limited to special operations aimed at the protection of human rights (Kaldor 2008, 36). This stems from the idea that interstate conflicts belong to the past. Just peace focuses on conflicts between nonstate actors or conflicts between a state and nonstate actors. Not state rights but individual rights should be protected. In other words, the individual rights of citizens are guaranteed by international treaties and outweigh the right of a state to defend itself through war (Kaldor 2008, 35).

The just peace theory has been criticized for its liberal and Western paradigm since it applies a Western concept of peace through Western ideologies and human rights (Allan 2006). Another line of critique has come from Catholic theologians who criticize the theory’s optimistic view of humanity and its lack of traditional Catholic notions such as sin. However, one of the fundamental errors of the just peace theory—namely, the assumption that the state is a less important actor in causing or solving a war—has not been dealt with in the existing literature.

The Ukraine War and Just Peace Theory

Since the end of World War II there has been a growing optimism in the international community due to the fact that the number of wars between states has declined (Love 2018, 62). Some scholars, such as American professors of international law Oona Hathaway and Scott J. Shapiro, see the development of international law as the main reason for this decline (Hathaway and Shapiro 2019, 62). Recent literature about just peace has focused mainly on so-called nonstate conflicts in the context of the theory of just peace (Kaldor 2008).

Russia’s attack on Ukraine has changed this trend abruptly. In fact, the war in Ukraine has changed the political and military situation in Europe and the world. Intensive defense cooperation was initiated in Europe, and NATO emerged from its hibernation. The secretary general of NATO, Jens Stoltenberg, stated in April 2022 that “the war has already had long-term consequences for our security. NATO needs to adapt to that new reality” (Treeck 2022). This new reality contains the possibility of a Russian invasion of NATO’s eastern member countries (Malnick 2022). The threat of global war is present now that the West is actively supporting Ukraine, and some analysts even argue that World War III is already a reality. One of America’s leading Russia experts, Fiona Hill, stated in 2022 that “we are already in the middle of a third World War, whether we’ve fully grasped it or not” (Hill 2022). These geopolitical changes have had direct consequences on the way the theory of just peace is perceived. The war in Ukraine calls for urgent reflection on the practical application of this theory.

Self-defense and the Question of Counteroffensive

Having outlined the features of just peace theory and the changes in the sociopolitical context, we are now in a position to evaluate the theory in light of the Ukraine war and to address the questions regarding justification of Ukraine’s self-defense and counteroffensives. We will see that the just peace theory fails in four ways when applied to the Ukraine war.

First, as we have seen from the perspective of the forms of just peace, the use of force is closely linked to international organizations such as the UN. Here the right to national self-defense is highly constrained, and the focus is not so much on protecting the nation as a whole but on protecting individual human rights. Just war scholars such as Michael Walzer have voiced their skepticism regarding the UN as a reliable protection force (Walzer 2004, 145). In the case of Ukraine, this skepticism was justified. Strictly from the perspective of just peace, Ukraine should have appealed to the UN to provide protection for its citizens through a peacekeeping operation, and negotiations with Russia should have taken place (Stahn 2020). However, it has become clear that the UN, and especially the UN’s Security Council, is internally divided. The Security Council was therefore unable to provide security guarantees to Ukraine and failed to create a framework for mediation (Murithi 2022, 65–66). Had the theory of just peace been strictly followed, large parts of Ukraine would have been occupied before the UN had come to Ukraine’s aid. With respect to the necessary swift defense of Ukraine, the just peace theory failed.

Second, it is important to keep in mind that Ukraine not only wants to defend itself against Russia but also launches counterattacks. Ukraine has launched several counteroperations and has even executed covert counterattacks on Russian territory to hit supply lines and destroy stationed military units (Miller and Khurshudyan 2023). From a just peace perspective, these counterattacks are difficult to accept, as they involve offensive warfare and opening a new front to achieve eventual peace. With respect to providing a justification for a real Ukrainian counteroffensive, the just peace theory also fails to help Ukraine.

Third, the theory does not focus so much on the rights of states but on individual human rights that transcend the rights of states (Kaldor 2008, 21). These human rights are to be guaranteed by international treaties and should ideally be protected by international security operations through the UN. Violence should primarily be exercised to ensure security of individuals, and therefore state security fades away. However, the war in Ukraine has shown that state security still matters. It is the Ukrainian nation that is a unifying factor and is often brought up in accounts of the fight against Russia (Brantly 2023). Moreover, because of Russia’s veto the UN Security Council has proved to be powerless both in condemning the invasion by Russia and in undertaking necessary concrete measures to protect individual human rights of Ukranians (Brunk and Hakimi 2022, 693). Instead, countries like the United States and the United Kingdom have pledged state-level assistance to Ukraine. The idea that the security for individual civilians will be protected through international oversight has utterly failed in Ukraine. A counterargument from defenders of the just peace theory could be that state security is implied in the protection of human rights since the Universal Declaration of Human Rights says, “Everyone has the right to a nationality” (art. 15). This would imply that everyone has the right to belong to a state that can continue to exist in some sense in the face of a threat. However, the situation in Ukraine shows that the United Nations, which should safeguard the human rights outlined in the UDHR, has failed to act accordingly. This failure to protect state security and the individual human right to a nationality is a third criticism of the theory of just peace arising from the Ukraine conflict.

The Lack of a Moral Framework

Fourth, beyond the lack of moral justification for state-level self-protection, just peace theory fails to provide a moral framework by which Ukrainian military personnel can justify their actions. The theoretical justification of a war or military operation has practical implications and provides moral meaning that Ukrainian soldiers need in their day-to-day actions. In his discussion of the theoretical justification for war, the Dutch scholar Pieter Vos emphasizes the need of a moral framework for soldiers. He writes, “The military profession is tough, not only because of the tasks, objectives, means or traumatising circumstances, but especially because the profession is exercised in a working environment characterised by moral evil and sin in which clean hands are impossible.” (Vos 2018, 173).

When soldiers cannot fall back on any moral-theoretical framework for the actions they perform, shame and guilt can develop (Iersel 2018, 65). A theoretical justification for going to war and action in war therefore remains necessary to sustain the actions that Ukrainian soldiers undertake from day to day. This theoretical insight is confirmed by Robert Latiff, who served in the US Air Force as a major general. He vehemently opposes the rejection of just war theory by Christian theologians because the theory provides a moral framework for soldiers. He writes, “I cannot state too strongly that officially abandoning just war teaching would be a terrible outcome for the Catholic Church and the militaries of civilized countries. It would be especially damaging to the individual soldier’s view of his profession and his proper role within it” (Latiff 2018, 72). Latiff warns strongly against abandoning just war theory and replacing it with a just peace theory. Just war concepts are important, according to Latiff, since “they serve first, to place boundaries on the permissible behavior of soldiers in war. Second, they recognize that, in war, soldiers see things most of us will never see and do things we hope never to have to do. Just war concepts provide soldiers with a framework to understand the basis of the violence with which they are tasked” (Latiff 2018, 73).

Just war theory is also considered relevant by military chaplains who have actual experience in taking care of the moral wounds of soldiers. One of them confirmed the theoretical intuition of the relevance of just war theory by explaining how American soldiers in Iraq and Afghanistan developed moral wounds since they were not introduced to “concepts of just war theory in advance,” which “would have provided . . . soldiers with an emotional structure that would serve, first, as a governor on unrestrained violence so often generated in combat and, second, to soften or mitigate the damage war does to their souls” (Latiff 2018, 74).

A theoretical justification for soldiers to fight from day to day is even more important in light of the general opinion of nations that in the case of the Ukraine war, Russia is the aggressor. This opinion was formally confirmed by a resolution of the UN General Assembly, which “deplores in the strongest terms the aggression by the Russian Federation against Ukraine in violation of Article 2 (4) of the Charter” (United Nations General Assembly 2022, italics original). Unfortunately, this formal condemnation is not accompanied by any concrete UN support to defend the Ukranian nation and civilians. This is closely related to the nature of the just peace theory, which focuses on solving conflict through dialogue on an international level. It does not, however, provide a moral framework for soldiers who are fighting a just war. Ukranian soldiers have a right to defend themselves, their country, and their fellow citizens according to laws of armed conflict. Just peace theory relies on diplomacy, dialogue, reaching agreement on territory through negotiations, and reconciliation after a war. All these elements are vital in the restoration of Ukraine and in the aftermath of the war. However, in the context of conflict itself it is clear that soldiers need to have a moral framework and moral concepts in order to justify their military actions and their use of force. Defenders of a just peace in the Ukraine war, such as Pope Francis and his personal emissary Cardinal Zuppi, have used concepts such as “creative peace” and have stressed the need for dialogue and patience in the restoration of peace (Sabatinelli 2023). However, these defenders of just peace theory have failed to provide a moral framework for the soldiers who are actually defending peace. The proponents of just peace theory have fallen silent on the traditional just war concepts that soldiers need in order to prevent moral wounds.

Christian and Augustinian Objections to the Worldview of Just Peace

Beyond these four concrete failures of just peace in relation to the Ukraine war, there is a fundamental problem with the worldview behind the theory of just peace: it takes as its point of departure an ideal situation in which actors resolve conflicts through dialogue and nonviolence.

The ideal of peace for humanity, and the absence of war and violence, recalls the message of Christmas night when peace on earth was announced. It is no coincidence that key proponents of the theory of just peace link it to Catholic ethics (Berger et al. 2020). According to Catholic defenders, the theory is a logical result of a centuries-long process of reflecting on peace within the Christian tradition. This refers to the work done by various popes to eliminate war and promote peace. For example, Pope John XXIII, Pope Paul VI, and Pope John Paul II each wrote that the church cannot accept war and violence. In recent decades, different popes have stated that war is not the means to achieve justice. For example, Pope John XXIII wrote in the encyclical Pacem in Terris, “In this age which boasts of its atomic power, it no longer makes sense to maintain that war is a fit instrument with which to repair the violation of justice” (John XXIII 1963, para. 127). Pope Francis promotes the theory of just peace and argues that dialogue and not war is central to settling conflicts. The Catholic Church has a great advantage in this dialogue because of its transnational character and the many traditions and cultural backgrounds gathered in the same institution (Appleby 2010, 6).

Even though just peace is in large part compatible with the core message of Christianity, it lacks one important element of the Christian tradition, which has become apparent in the Ukraine war. Christian theology not only presents the ideal of human beings united in neighbor-love with one another, but it also stresses human weakness and the fallen state of human beings. In Christian thought, human beings have a tendency toward evil, and they struggle to put neighbor-love into practice. This deficiency is not solved through human progress but will be present until the end of the world. This intuition was recognized by President Obama in his acceptance speech for the Noble Peace Prize in 2009: “We must begin by acknowledging the hard truth: We will not eradicate violent conflict in our lifetimes. There will be times when nations—acting individually or in concert—will find the use of force not only necessary but morally justified” (Obama 2009).

According to the church father Augustine, the absence of sin and evil will only be realized at the end of the world. Until then, there is no perfect justice on earth (Corey and Charles 2012, 54). The key to understanding Augustine’s view of the present age can be found in his City of God, where he writes, “On the one side are those who live according to man; on the other, those who live according to God . . . two cities or two human societies, the destiny of the one being an eternal kingdom under God, while the doom of the other is eternal punishment along with the Devil” (Augustine 1966, 15.1). From this understanding Augustine develops his view of just war, which should be understood in the context of restoring moral order. The goal of this restoration is “the sake of social peace, what [Augustine] calls the tranquillitas ordinis” (Charles 2005, 595). Therefore, in book 19 of the City of God, Augustine states that the wise person will conduct war since war is a necessity because of human sin (Carneiro 2016, 206). Some scholars even argue that just war in the Augustinian sense is an evangelical act of neighbor-love, since the innocent and the weak should be protected by authorized force (Ramsey 1968, 143; Gregory 2014, 50–52).

In his just war theory, Augustine constantly focuses on the restoration of moral order and stresses the fallen state of human beings (Corey and Charles 2012, 54). He states that war is a consequence of the destruction of this order. This means that if the government of a country fails to quell sin, it is quite possible that this will manifest itself in a war with surrounding countries. Augustine argued that not all human beings will conform to the ideal image of humanity as presented in Scripture. Good and bad people will live side by side until the end of the world. The Augustine scholar Eric Gregory summarizes this view: “there is no ‘just society’ or ‘just peace’ until the close of history” (Gregory 2020, 525).

Ultimate peace and justice are therefore not possible in temporal life. The Ukraine war shows that war remains a relevant factor. A theory of war and peace should reckon with the fallen state of humanity, but the theory of just peace tends to forget these Christian and Augustinian notions and operates from the optimistic worldview that ultimate peace on earth is achievable through dialogue. It departs from the Augustinian notion of sin and the distinction between the two cities that intermingle on earth.

The optimistic worldview of just peace theory can be clearly seen in an article written by the American theologian Gerald Schlabach, who was one of the participants of the aforementioned Nonviolence and Just Peace Conference in Rome in 2016. He states that nonviolent resistance campaigns are more successful than violent conflicts. According to Schlabach, just war theorists should “join the call to encourage the teaching and training of active nonviolence within a robust framework of just peace.” This nonviolence is a positive concept since it is “creative diplomacy, training of local communities and regional leaders and demilitarized police forces.” His message to civilians who are being conquered by a foreign force is one of nonviolent resistance (Schlabach 2017). When one thinks about the consequences of this message for the population of Ukraine, the conclusion can only be that the worldview of these just peace theorists is not only optimistic but also “naïve and potentially dangerous” (Latiff 2018, 76). This criticism has been made by other scholars as well (Steinfels 2017).

When applied to the Ukraine war, the nonviolent strategy of just peace theorists fails. The list of Russian war crimes against Ukrainian civilians is extensive. It includes the abduction of more than 121,000 Ukranian children and the killing of some of their parents (Schnell 2022), torture and killing in “filtration camps” in places such as Mariupol (Bachega 2022), and the Bucha massacre in which civilians were tied up, shot in the head, and buried in mass graves (Schreck, Burns, and Fisch 2022). The idea that the war criminals who committed these crimes would be open for dialogue or creative diplomacy stems from a wrong understanding of the evil that can claim the human person. To recommend nonviolence, creative diplomacy, and nonviolent resistance to the civilians of Ukraine in the face of these crimes is naïve and perhaps even cynical. These atrocities show the fallen state of human beings and the fact that evil is a reality in the contemporary world. Sometimes evil enters people in such a way that dialogue is no longer an option. The response to this evil cannot be the elimination of necessary, self-defensive violence because this will render the Ukranian civilian population harmless. Instead, these civilians deserve to be protected by military force.

The just peace theorists fail to recognize that military force is not intrinsically evil but, rather, a last resort that has been regarded by Augustinian thinkers as a necessary tool to maintain security in a sinful world. Blaise Pascal, another Christian thinker in the Augustinian tradition, once wrote that justice cannot exist without force: “It is proper that what is just should be obeyed; it is necessary that what is strongest should be obeyed. Justice without force is helpless, whereas the use of force without justice is tyrannical. Justice without force is futile, for there shall always be the wicked; but force without justice is always to be condemned. It follows that we must always combine justice and force, and, to this end, what is just must always be made strong, or what is strong just” (Pascal [1660] 2004, 1160). The just peace theory forgets this element of force and the threat of force that is necessary to achieve justice. Justice can be wished for but ultimately needs force to be achieved. The war crimes against Ukranian civilians have shown the relevance of combining justice with military force.

In Search of a New Version of Just War

Although the theory of just peace provides important elements that are relatively underdeveloped in the theory of just war, it cannot be a complete substitute for the theory of just war. The war between Russia and Ukraine shows, first, that interstate conflict has not disappeared from the international arena. Second, it shows that humanity is fundamentally affected by sin. Just war theory is necessary to condition armed conflict. Moreover, a shift from just war to just peace may open the way for unbridled violence because it abandons the hope that armed conflict can be morally conditioned (Iersel 2018, 61).

In the search for a new variant of just war, the American political philosopher Maryann Cusimano Love offers an interesting approach (Love 2018, 60–71). She argues that the two theories should be understood as in dialogue rather than in opposition to each other. Just war theory is necessary, she states, but in the context of just peace. Just war theory is limited, as it does not indicate how sustainable peace can be achieved. This point is recognized by contemporary just war scholars who underline the Augustinian notion that peace is the cornerstone and goal when reflecting upon war (Shadle 2016). Walzer has even argued that “implicit in the Theory of Just War is a Theory of Just Peace” (Walzer 2006, 4). Since the just war theory often explains this peace as a negative peace, it is limited and needs the just peace theory to broaden the concept.

At the same time, the just peace theory is also limited in that it does not address how wars can be morally conditioned. Love mainly emphasizes the jus in bello criteria that derive from just war theory and that are very helpful in limiting wars. Examples include the Geneva Conventions, the Genocide Convention, the International Criminal Court, and the ban on cluster munitions (Love 2018, 69).

A final point of dialogue between the two theories can be found in the concept of jus post bellum, which has its origins in just war theory (Stahn 2020, 18). Despite the fact that just war theory has traditionally aimed at creating peace, jus post bellum is often overlooked (Bass 2004, 384; Walzer 2004, 163). Some scholars have argued that there has always “been inadequate attention paid to considerations of jus post bellum in the Just War Tradition” (Williams and Caldwell 2006, 310).

Jus post bellum is a theory that deals with ending an armed conflict and provides conditions for rebuilding and restoring peace. Some scholars argue that these conditions should be implemented in a way that guarantees a sustainable and just peace (Bellamy 2008, 601). Although the relationship between jus post bellum and just peace is contested, a fruitful dialogue between the two theories is possible. Jus post bellum is mostly related to the third form of just peace—peace understood as reconciliation (Stahn 2020, 5). Since jus post bellum is understood to be part of the just war theory, elements and practical lessons from the third form of just peace can be adopted to enrich and expand jus post bellum. When applied to the Ukraine war, and under the condition that Ukraine will win, it is the duty of Ukraine to create criminal courts in order to hold just trials, “punish those guilty of war crimes,” and make sure that through dialogue or “economic reconstruction” a future war will likely be impossible (Bellamy 2008, 612). In seeking a moral framework for Ukraine to fight a just war, this element of jus post bellum should be included. In the case of a victory for Russia or a stalemate, it will be up to other countries to mediate and seek to uphold the conditions that jus post bellum requires. An unjust war cannot produce a just peace (Williams and Caldwell 2006, 316). Since it is highly unlikely that Russia will seek to obtain a just peace for Ukraine without any external force applied, it is necessary to apply jus post bellum in the context of just war, since this tradition will give Ukraine more concrete tools to apply force in a just way.

Conclusion

The Ukraine war has shown that interstate conflict still exists in the twenty-first century. The assumption that conflicts take place mainly inside states themselves has proved untenable. The war in Ukraine raises the penetrating question whether the theory of just peace is practically applicable to ensure the security of the state of Ukraine and its people. Indeed, in the theory of just peace, military self-defense is strictly limited and emphasis is placed on nonviolent conflict resolution with an important role for international organizations such as the UN in protecting universal human rights. However, the Ukraine war has shown that it is not international organizations but the state of Ukraine that is the primary protector of the Ukrainian people against Russian violence. A state’s self-defense seems not to be recognized in the different forms of the theory of just peace. Ultimately the just peace theory fails to address and justify Ukraine’s self-defense and necessary counterattacks.

In the new reality that has emerged since February 24, 2022, it is therefore important to continue to appreciate the contributions of just war theory. The shift from a theory of just war to a theory of just peace is mainly encouraged by Catholic theologians who wish to replace the just war theory. Instead of calling for the replacement of the entire theory, it is wiser to apply aspects of both theories in conjunction with the Augustinian understanding that the ideal world cannot be realized on earth. The contribution of just peace theory can be found in its definition of peace not as an absence of war but as entailing concrete criteria. Just peace and just war should not be understood in opposition to each other but rather in dialogue. In the fractured reality in which Ukraine operates, the right of self-defense remains crucial to protect the civilian population against war crimes. In thinking about just peace, just war must be included on the basis that jus in bello and jus post bellum will continue to have significance as long this world endures.