As the post-World War II international order shows signs of strain, allied leaders have begun to reassess its durability. At the 2026 Munich Security Conference, German Chancellor Friedrich Merz warned that Europeans must be prepared to “sacrifice” to secure their freedom and that “a divide has opened up between Europe and the United States.” At the World Economic Forum in Davos, Canadian prime minister Mark Carney described the international world order as undergoing a “rupture, not a transition.” British prime minister Keir Starmer emphasised that Europe must increasingly be prepared to “stand on our own two feet” to secure a democratic way of life. These statements reflect a growing perception that the foundations of postwar cooperation are changing.

In the modern era, durable international orders have emerged not from harmony but from shared catastrophe. The 1648 Treaty of Westphalia ended the Thirty Years War, a religious conflict that devastated much of Europe and killed millions. By recognising the sovereignty of states to govern their own territories and religions, it laid the foundation of the modern state system, normalised diplomacy, and checked hegemonic ambition through an emerging balance of power order. After Napoleon’s defeat, the 1814–15 Congress of Vienna established norms of mutual restraint among great powers that contributed to a century of relative stability in Europe. Conflicts remained bounded; none produced the system-wide collapse that defined the Revolutionary and Napoleonic Wars. Similarly, after World War II, the United States and Soviet Union accepted limits against direct confrontation, even as they competed globally. These arrangements were sustained not only by deterrence but by a shared awareness of the catastrophic consequences of escalation.

Today, that shared memory has faded. The United States and China are engaged in structural rivalry spanning economic, technological, military, and geopolitical domains. Both countries remain embedded in global networks of finance, trade, and communication that neither fully controls and cannot easily abandon. This interdependence creates a paradox: states can neither achieve dominance nor autarky while relying on systems that require cooperation.

Realist theories explain this rivalry primarily in terms of the realpolitik of power, material interests, and strategic incentives. Offensive realism holds that in an anarchic system without a central authority, uncertainty about others’ intentions drives states to maximise power to secure themselves. This leaves little room for empathy, charity, or fairness, or what Abraham Lincoln called “the better angels of our nature.” Reflecting this view, senior US policy official Stephen Miller stressed in a recent interview that “You can talk all you want about international niceties and everything else, but we live in a world—in the real world—that is governed by strength, that is governed by force, that is governed by power. These are the iron laws of the world since the beginning of time.” In an interdependent world, however, efforts to dominate or exclude intensify rivalry and the likelihood of conflict.

At Davos, Carney framed the emerging environment in similar terms, invoking Thucydides’ observation that “the strong do what they can and the weak suffer what they must.” His remarks highlight concern among America’s allies that dependence on US power for security and goods leaves them vulnerable to coercion and subordination, underscoring the structural reality that power disparities shape political outcomes. Carney and other allied leaders, including French President Emmanuel Macron, propose a coalition of lesser democratic powers to counterbalance great-power rivalry, reflecting the logic of “defensive realism”: the view that states seek security primarily by balancing rather than maximising power, and that interdependence can serve as a stabilising foundation of order.

Yet psychological and anthropological research indicates that material interests alone do not determine political action or allegiance. Communities do not only respond to external pressures, but also to how those pressures are experienced. Authority perceived as legitimate is more likely to be accepted; authority perceived as coercive or degrading is more likely to provoke resistance. This response reflects “moral culture”: the shared framework of values, narratives, and expectations that defines legitimate authority and acceptable conduct. Moral culture shapes whether influence is experienced as leadership or domination, cooperation or coercion.

This psychological and cultural dimension is largely absent from offensive realism, which assumes actors pursue security and advantage through material interests and incentives, including coercion when necessary. Yet coercion can erode the moral culture that sustains cooperation. When external pressure threatens identity or dignity, actors may resist rather than submit, even when submission appears materially advantageous. Moral culture is likewise underdeveloped in defensive realist prescriptions emphasising balancing coalitions of lesser powers. The durability of these coalitions depends on more than converging material interests. Coalitions formed solely in response to threats remain psychologically fragile and ineffective unless they cultivate shared moral frameworks rooted in values that sustain willingness to bear the costs of resistance.