The recent military strike by the United States and Israel against Iran has provoked intense global debate. Russia, China, and North Korea quickly condemned the intervention as a violation of international law, and many Western commentators echoed similar accusations, appealing to the prohibition of the use of force found in the United Nations Charter. Such reactions assume that the international order is fundamentally governed by stable legal norms capable of regulating the conduct of states.
Yet the reality of international politics appears far more fragile. For more than two centuries, international law has rarely functioned as a sovereign authority capable of enforcing its own norms. From the wars of Napoleon to the upheavals of the twentieth century and the conflicts of the present day, decisive political events have often been shaped less by juridical principles than by the balance of power. Even the creation of the United Nations after the Second World War has not eliminated this structural problem. The international system lacks a universal authority capable of compelling obedience to law. In such an environment, appeals to international legality alone cannot guarantee peace or justice.
To evaluate such situations properly, one must turn to a deeper moral framework. The theological synthesis of Thomas Aquinas offers such a framework through his account of Providence, Law, and Charity.
Aquinas situates political authority within the broader order of divine providence. God governs the world through secondary causes, including human authorities who participate—however imperfectly—in this providential ordering. As Aquinas explains, divine providence directs creatures through created agents that cooperate in the governance of the world (Summa Theologiae I, q.103, a.6; q.105, a.5). Political authority therefore belongs to the structure through which God orders human society toward the common good.
The purpose of this authority is not arbitrary domination but the promotion of the common good. Aquinas defines law as “an ordinance of reason for the common good, promulgated by one who has care of the community” (Summa Theologiae I–II, q.90, a.4). Without authority capable of promulgating and enforcing such ordinances, law cannot function properly. The weakness of the international system today reflects precisely this problem: there exists no political authority with genuine care of the entire global community capable of enforcing universal legal norms.
Aquinas also insists that all human law ultimately derives its legitimacy from a deeper moral order. Natural law, he explains, is the participation of rational creatures in the eternal law of God (Summa Theologiae I–II, q.91, a.2). Political communities remain stable only when their laws reflect this moral structure rooted in human nature. When nations abandon this objective moral order, legal norms become subject to the shifting interests of power.
This insight was powerfully reaffirmed by Pius XII in his encyclical Summi Pontificatus (1939). Reflecting on the outbreak of the Second World War, he identified the rejection of the natural law and of the moral order grounded in God as the deepest cause of modern political disorder. A stable international peace, he argued, cannot be built on purely procedural norms or shifting political agreements; it must rest on the “unshakable foundation of the natural law and divine revelation.”
Aquinas’ moral analysis also illuminates the dangers of revolutionary violence. In the Secunda Secundae he analyzes the vices opposed to charity and traces how interior disorder gives rise to social conflict. Hatred and envy lead to discord and contention, which in turn lead to schism, war, and sedition (Summa Theologiae II–II, qq.34–43). Sedition, he explains, is the disturbance of the unity of the political community and ordinarily constitutes a grave sin because it attacks the common good (Summa Theologiae II–II, q.42, a.1).
This does not mean that all resistance to unjust authority is forbidden. Aquinas recognizes that political authority may become corrupted when rulers govern for private advantage rather than for the good of the community. In such cases a tyrant may legitimately be removed by the political community if it possesses the authority to do so.
Yet Aquinas strongly warns against private tyrannicide. In De Regno (I, 6) he explains that when individuals assume the right to eliminate rulers based on private judgment, the result often proves worse than the tyranny itself, because the destruction of authority can unleash disorder, civil conflict, and the collapse of political unity.
The Church’s contemporary teaching reflects this Thomistic prudence. The Catechism of the Catholic Church, in paragraph 2243, allows armed resistance to oppression only under very strict conditions: grave and prolonged violations of fundamental rights, exhaustion of peaceful remedies, well-founded hope of success, the avoidance of worse disorders, and the absence of better alternatives. What is envisioned is not private assassination, but responsible resistance ordered toward the restoration of justice and the preservation of the common good.
When these principles are applied to the present geopolitical situation, a balanced conclusion emerges. The weakness of the international legal order does not eliminate moral norms, but it does mean that states cannot rely on global institutions alone to secure justice and peace. In a world where no universal authority exists to enforce international law, political communities retain the responsibility to defend themselves and to protect the conditions necessary for the common good.
The Christian tradition does not glorify war, yet it recognizes the tragic necessity of defense in a fallen world. Aquinas permits war under the strict conditions of legitimate authority, just cause, and right intention (Summa Theologiae II–II, q.40, a.1). The ultimate aim of such action must always be the restoration of peace, understood as the tranquility of order grounded in justice.
Between naïve legalism and cynical power politics lies the demanding path proposed by the Catholic tradition: a path grounded in divine providence, structured by law rooted in natural justice, and guided above all by charity, which seeks to defend the common good without abandoning the moral order upon which true peace depends.
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