With the end of unipolarity, security competition among the great powers—China, Russia, and the United States—is back with a vengeance. Given the possibility of war between rival great powers, the purpose of this article is to analyze great power war. My central claim is that war is the dominant feature of life in the international system, mainly because of the nature of politics. In particular, politics is a fundamentally conflictual enterprise with the ever-present possibility of violence in the background. This argument, which differs from Carl von Clausewitz's famous claim that war is an extension of politics by other means, is rarely made in the international relations literature. I examine how the interplay between politics and war affects how states both initiate and conduct armed conflict. What are the limits on states starting wars, and how do political and military factors contribute to their escalation? I argue that it is almost impossible to put meaningful limits on when states can start wars, and that there is a powerful tendency for wars to escape political control and escalate.

The liberal international order, erected after the Cold War, was crumbling by 2019. It was flawed from the start and thus destined to fail. The spread of liberal democracy around the globe—essential for building that order—faced strong resistance because of nationalism, which emphasizes self-determination. Some targeted states also resisted U.S. efforts to promote liberal democracy for security-related reasons. Additionally, problems arose because a liberal order calls for states to delegate substantial decisionmaking authority to international institutions and to allow refugees and immigrants to move easily across borders. Modern nation-states privilege sovereignty and national identity, however, which guarantees trouble when institutions become powerful and borders porous. Furthermore, the hyperglobalization that is integral to the liberal order creates economic problems among the lower and middle classes within the liberal democracies, fueling a backlash against that order. Finally, the liberal order accelerated China's rise, which helped transform the system from unipolar to multipolar. A liberal international order is possible only in unipolarity. The new multipolar world will feature three realist orders: a thin international order that facilitates cooperation, and two bounded orders—one dominated by China, the other by the United States—poised for waging security competition between them.