proposal

The End of Pax Americana and the Rise of China: The Entrenchment of "MAGA" and China

Before "Pax Americana"

The so-called Pax Americana—the U.S.-led order that, over decades, came to be treated less as a contingent arrangement than as a structural feature of the system—endured long enough to be mistaken, even by otherwise discerning observers, for a permanent fixture of world politics. It would, however, be a serious—indeed fundamental—error to suppose that the United States will, by the mere perpetuation of precedent, remain indefinitely the world's preeminent power, exercising predominance through a vast network of allies and projecting influence into every strategically significant region without sustained challenge. Under the second administration of Donald J. Trump, American hegemony has entered—if not in formal proclamation, then in operative fact—its terminal phase; with that passage international politics has shifted, not by imperceptible degrees but qualitatively, into a new and uncertain stage.

A glance at the longer arc of American history shows that sustained engagement in the affairs of the wider world is, in truth, a comparatively recent development.

In practice, the most durably institutionalized form of external commitment has been the alliance: an association that requires a willingness to bear the costs of military action, to assume the risks of failure, and to bind one's fortunes to those of others in matters of war and peace. Modern alliances, moreover, now encompass integrated armaments production, logistics, and even command structures—arrangements that exhibit the attributes of complex international institutions. Such integration long ago passed into routine.1 From the seventeenth to the nineteenth century, such alliances defined modern European statecraft. They were concluded in the face of common threats, dissolved when those threats receded or transformed, and gave way, in due course, to new combinations—each shift occurring under the familiar rubric of the balance of power. War was at once cause and consequence of shifting alignments, and the making and unmaking of alliances furnished the basic rhythm of European diplomacy. In the literature, this period has often served as the archetype of the alliance phenomenon. More recently—particularly to distinguish it from the "asymmetric alliances" of the Cold War—scholars have preferred the label "symmetric alliances."2

From its inception in the eighteenth century, the United States maintained a pronounced skepticism toward this European practice. The Republic secured independence from Britain while affirming its identity as a free and peaceable polity, fundamentally distinct from what the founders regarded as the despotic, war-prone powers of the Old World. Alliances—inseparable then from the wars they served—appeared emblematic of Europe's corrupt and dangerous statecraft. The young Republic was also weak: unable to match European resources, it had every reason to fear that entanglement would draw it into others' quarrels and perhaps subject it to their domination. For reasons of principle and prudence—rooted as much in identity as in strategy—alliances with European powers were deemed undesirable. Aversion hardened into what later generations would call isolationism.3 The point bears recalling in assessing the foreign-policy instincts of the second Trump administration.

The Cold War and the Formation of "Pax Americana"

Why, then, does the United States now preside over a global network of alliances? The decisive turn came on December 8, 1941, when Japan's attack on Pearl Harbor dispelled any lingering illusion that the Western Hemisphere's security could be assured without deep and continuous engagement in the wider world. By then the United States had already attained overwhelming predominance in the Western Hemisphere—regional hegemony in the strict sense—yet it could not forestall an attack on Hawaii. The episode crystallized within the policy establishment a conviction—destined to shape strategy for decades—that it was imperative to secure strategic depth and, above all, to foreclose the rise, on the Eurasian continent, of any regional hegemon capable of projecting power across the oceans into the Western Hemisphere. Securing and preserving the position of sole regional hegemon was thus recast as the sine qua non of American security.

An equally potent force driving the postwar transformation of U.S. policy was the perceived threat posed by communism, led by the Soviet Union, as a political and economic alternative to liberal capitalism. In the eyes of American strategists, the global expansion of communism would not merely diminish the appeal of liberal economies and democratic governance; it would confine them to minority status, restricting the United States—geopolitically and ideologically—to the Western Hemisphere. That prospect was held to be strategically intolerable.4 To avert such an outcome, policymakers concluded, it was necessary to anchor in Eurasia—and particularly in Western Europe and Japan, the very regions deemed capable of challenging U.S. primacy—a grouping of states sharing the American model of economy and polity. Without such a configuration, the broader conception of American security—embracing not only territorial defense but also the preservation of economic structures, political institutions, and a way of life—could not be maintained. Over the course of World War II and the early Cold War, the logic hardened into an axiom.

The alliances the United States forged as a consequence differed fundamentally from the symmetric pacts of European diplomacy—temporary compacts concluded in response to a common threat and dissolved once that threat had passed. From their inception, these U.S.-led alliances were bound up with a larger project: the reorganization of numerous states into a strategic environment congenial to American interests—in short, the creation of a U.S.-led international order. As I elaborate elsewhere (When the Empire Yields: Politics of Reward and Coercion in American Asymmetric Alliances, Iwanami Shoten, 2024), these were "asymmetric alliances," in which the patron state—the United States—provided an overarching framework integrating military power, economic systems, and international institutions, while client states—Japan, the Western European powers, and others—aligned themselves within that framework.

What, then, was this order—variously styled "Pax Americana," "the Free World," "the West," or "the liberal international order"? In theoretical terms, three features were decisive. First, it rested on overwhelming American military power. Second, it generated prosperity by promoting free trade among Western states under its aegis. Third, it fostered cohesion through a range of international institutions, alliances among them. The same triad explains how the order integrated so expansive a domain: it offered military protection and economic gain within a rule-governed system—while the exercise of American power within this framework was, at least formally, subject to self-imposed limits. For subordinate states, the combination made participation advantageous; accordingly, they long recognized and accepted U.S. leadership. Even after the Cold War—and the disappearance of the Soviet Union as common threat—the United States preserved these alliances, ruling the post–Cold War world with a predominance often described as unipolar. It endured because incentives aligned.5

The Beginning of the End—From the Iraq War to the Biden Administration

The edifice of national strategy that had underpinned American foreign policy since the Cold War began to show visible fissures in the first decade of the twenty-first century—ironically, just as American power stood at its zenith. In the wake of the terrorist attacks of September 11, 2001, the administration of George W. Bush—animated by anger, fear, and an unshakable sense of supremacy—embarked upon what, viewed in retrospect, was the opening act of the American era's denouement. Two events defined the turn: the invasion of Iraq in 2003 and the global financial crisis of 2008.

The cumulative effect of these military, diplomatic, and economic traumas was such that by the early 2010s a discernible shift had taken place in foreign-policy discourse. The Cold War consensus—that the enduring security of the United States, understood broadly to encompass not only territorial defense but also the preservation of economic foundations, political institutions, and national values, required the permanent maintenance beyond the Western Hemisphere of friendly states sharing America's political and economic systems—was slowly but unmistakably eroding. The consensus frayed; the habit of assumption died hard, then failed.6

It was against this backdrop of strategic uncertainty that the first Trump administration assumed office in January 2017. Of particular and lasting significance was its policy toward China. To be sure, the pivot from cooperation to strategic competition had begun under Barack Obama, with 2014–2015 marking an inflection. Yet Obama's approach remained within the established paradigm: restrain Chinese behavior by strengthening military ties with allies, advancing free trade, and expanding international institutions—the Trans-Pacific Partnership (TPP) serving as the most conspicuous emblem. Trump, by contrast, rejected not only engagement with China but the very pillars on which it had rested: free trade, multilateral institutions, and even alliances, which he cast as threats to the welfare of American workers, particularly in manufacturing. What followed was a novel synthesis: a hard line toward China conjoined to hostility toward the very instruments through which previous administrations had sought to shape the international environment.

This departure was not reversed under Joseph R. Biden, who took office in January 2021; it was, rather, codified. Although Biden campaigned as a critic of Trump, his foreign policy displayed marked continuity. Most decisively, he identified China as the sole state capable of mounting a serious challenge to U.S. primacy, designated it the foremost strategic competitor, and adopted measures aimed at constraining its economic and technological development.7 The distinctive feature of his approach lay in the attempt to embed Trump-era impulses within renewed cooperation with allies: the U.S.–Japan alliance and NATO were strengthened, and new minilateral groupings—AUKUS and U.S.–Japan–Republic of Korea trilateralism—were expanded.

Yet beneath this outward show of alliance solidarity lay a continuity with Trump: the primary concern remained extracting resources from allies. The United States did not prevail in the Cold War merely by deterring the Soviet Union; it prevailed by presenting the more attractive choice—by fostering a Western order whose political systems and prosperity outshone those of the East. 8 In Biden's foreign policy, this sensibility never surfaced. Early in his term some observers discerned a systemic rivalry between democracy and authoritarianism; I cannot concur. While the administration was deeply committed to securing America's own economic and technological advantages, it showed no comparable interest in ensuring the prosperity or political stability of other democracies, Japan included. The result fell far short of genuine "systemic competition."

The absence of a coherent economic vision was emblematic. China's influence rests chiefly on economic reach; yet in the decade since Washington's withdrawal from the TPP, no forward-looking initiative of comparable scale has been forthcoming. Policy remained narrowly focused on preserving U.S. technological primacy—an objective that, as of this writing, has manifestly failed to achieve its intended effect. American specialists on Asia have repeatedly underscored the need for an economic strategy. The difficulty was not ignorance but politics: accelerating polarization rendered serious consideration of such measures politically impossible.

The End of the End—Trump, the Demise of Pax Americana, and China

The U.S.-led order rested on three pillars: American military engagement, free trade, and international institutions and norms. By the time of the Biden administration, the economic order predicated on free trade had already been hollowed out, while the normative foundations were gravely compromised by the wars in Ukraine and Gaza. With the advent of the second Trump administration, the remaining two pillars—free trade and international norms and institutions—fell away altogether, and even the final redoubt, America's military engagement, began to waver. Given that hostility to foreign entanglements and to free trade has taken deep root in American politics—and shows every sign of further entrenchment—the conjunction of these elements must be judged to have entered its final collapse. By 2025, Pax Americana—the U.S.-led international order—had, in substance, come to an end. The facade lingered; the substance had fled.

Within the first six months of the second Trump administration, the most conspicuous development was the precipitous loss of credibility, expectation, and trust in American words and deeds. First, a rapidly consolidating consensus took hold—among allies and non-allies alike—that the United States would not return to free trade in its former guise, nor resume its role as leader of international institutions and norms. What little remained of expectations for U.S. leadership evaporated. Second, no coherent replacement strategy emerged. Today, factions with starkly divergent visions vie for influence; the habit of compromise has long since withered. Within a single administration, policies can lurch from one course to another; across administrations, the swings are greater still.

The immediate consequence is a decline in American influence both in East Asia and globally. Allies and friendly states, Japan included, now find themselves compelled to adjust to a United States whose policy trajectory is marked by heightened uncertainty. This will manifest first, and most visibly, in the economic and diplomatic spheres. Early indications are discernible: in Asia and Europe alike, governments are exploring independent arrangements for economic cooperation. Given the configuration at hand, the erosion of cohesion between the United States and its allies—in economic policy, in the articulation of norms, and in institutional cooperation—is, by now, all but inevitable.

The implications for security, particularly for the alliance network in East Asia, are harder to gauge, not least because the trajectory of U.S.–China relations is as yet uncertain. Once the United States has lost both the intention and the capability to maintain the order, the persistence or strengthening of its alliances will depend upon the existence of a common adversary capable of serving as focal threat. In the heyday of the Western order, the presence or absence of such a threat was not always decisive: the fate of alliances was tightly bound to American hegemony, and the dissolution of NATO or the U.S.–Japan alliance would have signified nothing less than the end of that hegemony itself. Now that Washington has abandoned the strategy of maintaining and expanding the order, alliance durability is likely to depend—much as in the age of European diplomacy—on the locus of threat perception. Only one state plausibly capable of establishing regional hegemony on the Eurasian continent—and thereby posing a threat to American national defense—remains: China. For this reason, the U.S.–Japan alliance is unlikely to unravel; Japan remains the only state with which the United States can coordinate, in peace as in war, an integrated strategy toward China.

Yet the Trump administration's approach to China stands unresolved. The Department of Defense continues to articulate a policy of deterrence and alliance strengthening in line with established practice, and most experts still identify China as the foremost strategic competitor.9 Such pronouncements—and the advice of specialists—notwithstanding, the administration has not implemented measures, whether in security or diplomacy, that match the strategy it articulates. On the contrary, its principal initiatives in the first six months have been counterproductive from the standpoint of coherence: undermining allied coordination through tariffs; showing studied indifference to Taiwan; nudging Southeast Asian states toward Beijing; straining ties with Europe over Ukraine and with India; and diverting military resources to the Middle East. The president's attention to China runs chiefly to economic matters, not security, and the administration's hardliners on China have been in steady decline.

Should the United States, in pursuit of immediate economic advantage, acquiesce in China's attainment of regional hegemony, the U.S.–Japan alliance would inevitably begin its descent into irrelevance. Thus, the future of that alliance—and of the American network in East Asia—hinges on the course of U.S.–China relations and, by extension, on China's relations with Asian states, Japan included. Conversely, Chinese choices have become decisive in determining the fate of alliances in East Asia, and with them the region's future. With Pax Americana's demise, the U.S.–Japan alliance has shifted from a stable pillar of hegemony to a provisional arrangement—its fate contingent on China's behavior as the "common threat."

(Nobuhiko Tamaki, Ph.D. Professor, Chuo University)

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