- October, 2023
- Fierce debates about whether the world is multipolar, unipolar, or bipolar are often shaped by theories about which system is best for U.S. interests. Although the evidence suggests that the world is entering a period of unbalanced multipolarity, there’s little evidence that this is worse for U.S. interests than the alternatives. Leaning in to multipolarity offers U.S. policymakers a diverse array of choices to serve future needs.
Executive Summary
Debate over questions of polarity — that is to say, whether the world is entering a period of multipolarity, unipolarity, or bipolarity — have become increasingly intense among both international relations scholars and policymakers. The United States’ winning record during the Cold War has led many to assume that a new bipolar competition with China is emerging and offers the best opportunity for success. These assumptions, however, are questionable. The authors of this paper test two key assumptions surrounding this debate. First, the paper evaluates what kind of international system is emerging: multipolar, bipolar, or unipolar. Second, the paper explores the potential each of these systems carries for increased risk of conflict between major powers compared with a bipolar international system. Assessing these two assumptions explicitly is important because the second assumption is too often addressed implicitly in discussions of the first, with policymakers in particular tending to favor the system they believe will be best for the United States.
Looking at a variety of data sources — which capture not just China’s growth, but also the major economic gains made by middle powers in recent years — the authors conclude that the emerging distribution of power is best described as a system of “unbalanced multipolarity.” Power is increasingly diffusing away from the superpowers toward a variety of capable, dynamic middle powers that will help to shape the international environment in coming decades. The question of U.S. policy is more complicated: Though academic literature indicates that indeed more wars occur during periods of multipolarity, the evidence suggests that these are more likely to be civil wars and low-scale conflicts rather than great power wars. From the point of view of U.S. national interests, a lower risk of great-power war — particularly in the nuclear era — may be preferable to the alternatives.
The paper concludes by examining current U.S. strategy in the context of an emerging multipolar order and argues that the Biden administration’s approach is heavily dependent on potentially inaccurate assumptions about bipolarity, as well as the ability of the United States to re-run the Cold War playbook. Attempts by the United States to build large coalitions in opposition to China are unlikely to be successful in a more multipolar system, and the risk of direct conflict may be higher if the United States engages in a Biden-style “bloc-building” strategy. The authors instead make the case for embracing multipolarity as a core tenet of U.S. foreign policy: cooperating broadly with other countries in bilateral and minilateral formats, striking diverse and mutually beneficial trade agreements, and promoting friendly alternative sources of military power by pushing allies to take greater ownership of their own defense.
Introduction
In a recent edition of Foreign Affairs, the political scientists William Wohlforth and Stephen Brooks made a provocative claim: “There is perhaps no more widely accepted truth about the world today than the idea that it is no longer unipolar,” they argue. In their view, the world is neither bipolar nor multipolar, and it is not about to become either.1
Wohlforth and Brooks’ view is increasingly out of step with the statements of leaders around the world, U.S. partners and adversaries alike, many of whom openly argue that the world is entering a multipolar era. India’s prime minister, Narendra Modi, has openly sought to speed up the transition to global multipolarity, while French President Emmanuel Macron shocked other European leaders when he said that Europe should “seek to be a third pole” in an emerging world order.2 Brazilian President Lula da Silva has pursued stronger ties with China while maintaining partnerships with the United States, European Union (EU), and Russia, with his finance minister explaining that Brazil is “too big to be choosing partners.”3 Meanwhile, Russian President Vladimir Putin told a conference in June 2022 that “A multipolar system of international relations is now being formed. It is an irreversible process; it is happening before our eyes.”4
Much of the discussion surrounding global politics today — particularly the role of the United States — is shaped by this dispute over the structure of the international system. States in the developing world do appear to enjoy increasing amounts of leverage in international politics, yet most global military power and economic strength remains concentrated in the West or in China. The war in Ukraine has only reinforced this contradiction: The United States has found it more difficult to pull together a global coalition than it might have in past decades, particularly as the states of the Global South seek to hedge their bets. But U.S. sanctions against Russia and military aid to Ukraine have nonetheless been game changers in the conflict, enabling Ukraine to fight against the odds.
In short, despite the common invocations of a “multipolar world,” the overall picture of whether the world is transitioning to multipolarity, a bipolar competition with China, or something else entirely remains unsettled. There is also little agreement among observers about which system would be more beneficial to the United States: bipolarity or multipolarity. Though these may seem like dry, academic debates, they carry significant ramifications for U.S. foreign policy.
This article thus tests the two most common assumptions surrounding this debate: first, the assumption that the world is becoming multipolar, and second, the assumption that multipolarity will be more dangerous for the United States than either bipolarity or unipolarity. Understanding the kind of international system that is emerging — and its risks and possibilities — is essential for U.S. policymakers to formulate effective and pragmatic foreign policy.
Polarity, Reconsidered
DEFINING POLARITY
International relations scholars have always focused on polarity as one of the core factors that can explain why an international system is stable or unstable (i.e., whether there are many wars or few wars). Simply put, polarity is the distribution of power in international affairs across all countries. Without at least an intuitive understanding of polarity, which is to say the distribution of power within the international system, one could not, for example, understand why the Spartans — in Thucydides’ famous phrasing — so feared the rise of Athens.5 The emergence of another dominant actor in the international system, produced by the long, slow shifting of demographics, economic power, or military capabilities is among the most pressing concerns for states in recorded history and may presage a potential power transition in the international system. At the most basic level, polarity is a function of the distribution of capabilities and resources in the international system. As power shifts over time, new poles and new patterns of polarity emerge. There are three common categories of polarity:
- Unipolarity is a system in which one state is by far and away the most powerful in the system, rendering it nearly impossible for other states to challenge it. The term primarily applies to the period of American global dominance after the fall of the Soviet Union in 1991, but it could also be said to have existed regionally during periods of the Roman Empire in the Mediterranean, or the Mongols during antiquity.6
- Bipolarity is most associated with the Cold War standoff between the United States and the Soviet Union. It is a system in which two powers are relatively evenly matched and between them dominate the international system. The 18th-century rivalry between Britain and France is another such bipolar system, one in which the two European empires played out their rivalry across the Old and New Worlds.
- Multipolarity is a situation in which three or more powers of comparable rank jockey for position in the international system. There is no upper limit on the number of states that can be poles in a multipolar system, though typically between three and seven states are key players. This type of system can be balanced, with power distributed relatively evenly among several states, or unbalanced, with a few states clearly leading the pack. Multipolarity is by far the most common system in history, seen everywhere from the Thirty Years War in Europe through the Warring States Period in China. The best known example is pre-World-War-I Europe. Indeed, the dominance of multipolarity among the universe of available cases suggests one reason why it can be difficult to study the question of stability in the international system; there have been surprisingly few non-multipolar systems to draw insights from.7
This all seems clear in theory. In practice, however, the study of polarity contains more than a whiff of former Supreme Court Justice Potter Stewart’s old canard about pornography: “I can’t define it, but I know it when I see it.” Some studies have attempted to quantify polarity using measurements of power distribution within the international system. By these standards, unipolarity typically requires one state to hold 50% of the system’s power resources (an amalgam of military strength, economic factors, industrial capacity, and demographics). Bipolarity would require two states to jointly hold 50% of the power resources, and multipolarity three or more states to do so. Yet most studies of polarity rely on qualitative assessments of the international system. It is almost inevitable that such subjective ratings lead to conflicting assessments; across just three analyses in the literature, as one example, the international system in the year 1919 is assessed as either unipolar, balanced multipolarity, or unbalanced multipolarity.8
MEASURING POLARITY
The problem of measuring power is one of the oldest — and most challenging — questions in the study of international relations. State power is hard to observe in action, and few agree on its exact source. The ability to turn that power into concrete outcomes is heavily dependent on context. As political scientist Joseph Nye memorably put it, “Power . . . is like love; it is easier to experience than to define or measure.”9 Indeed, measuring power requires answering almost laughably big philosophical questions: Does power flow from the barrel of a gun (i.e., should we measure direct military capabilities)? Can it be purchased by a sufficiently wealthy state (i.e., should gross domestic product (GDP) or gross national product (GNP) be considered?) Or is it the result of people (i.e., does power derive from deep societal virtues, from human capital, or from mere demographic dominance)?
Only one thing is certain: Power — and thus polarity — seems to derive from some combination of these factors. As one recent report from the Rand Corporation states, “Nations rise and fall, succeed or fail in rivalries, and enjoy stability or descend into chaos because of a complex web of factors that affect competitive advantage.”10 To be a great power — a pole in the international system — requires competency in more than one area, from economics to military capabilities, population, and technical prowess. As political scientist Kenneth Waltz puts it: “No state can be a great power if its endowment in any of these elements of power is vastly outmatched by the most powerful states in the world in that particular domain.”11 It is perhaps no surprise then that scholars most commonly rely on observable factors to build an “elements-of-national-power” approach.12 These factors can be economic or population metrics, measures of military spending or capabilities, natural resource endowments, or an index that seeks to incorporate all these elements.13
The most widely used of these is the Comparative Index of National Capabilities (CINC) score produced by the Correlates of War Project, which provides a value for a state’s share of the “power resources” in the international system at any given time. Though frequently used, CINC scores are also somewhat problematic. A CINC score, which relies on traditional metrics, such as population and steel production — things essential for 20th-century mechanized warfare — is not necessarily useful for capturing the strengths or weaknesses of modern, technologically advanced militaries. More modern indices, such as the Lowy Asia Power Index, attempt to achieve a better result by incorporating technological and alliance-based factors.
Some scholars instead favor the use of simple economic metrics (i.e., gross national income [GNI] or GDP), on the basis that economic power can be translated into military power if given sufficient time. Indeed, if one assumes that power is relatively fungible, then economic measures are an excellent way to assess latent power. Consider the United States itself, which in 1939 possessed the 19th-largest military in the world. A mere five years later, the United States had by far the most powerful military in the world, thanks to the aggressive transformation of the U.S.’ industrial base into military production. Measuring latent power is also an excellent way to account for the fact that different states make different choices when it comes to the traditional “guns-vs.-butter” tradeoff. Over a medium-to-long-term horizon, economic measures are a much better measure of potential or latent power than any emphasis on military spending or capabilities.
Yet, as with technological and military prowess, there are no straight-line correlations here. Not all states have the capacity to turn economic success into military power, due to constraints in population or size. The world’s wealthiest state on a per-capita basis, for example, is the natural gas-rich Qatar; with only 300,000 citizens, it could not possibly field a large military. Or consider Russia. On paper, Russian armed forces should have annihilated their Ukrainian counterparts during their 2022 invasion. But poor strategy, training, and corruption undermined Russia’s power potential. And modern post-industrial societies might find it harder to retool their defense industries for wartime in a hurry. It is easier to turn an automobile factory into an airplane factory, as was done during World War II, than to turn today’s call center into any kind of weapons production line.
Some economic measures also tend to overstate latent power. As the political scientist Michael Beckley highlights, a large population also comes with liabilities, something GDP does not explicitly account for. Think about it this way: Even the ancient Romans could not just turn peasants into soldiers. They also had to figure out how to feed, clothe, arm and — perhaps most important — train their new recruits. Beckley thus favors a measure of GDP multiplied by GDP per capita to capture some sense of both the size of an economy and its level of efficiency. Another alternative is to rely on measures that try to account for the liabilities mentioned above. The World Bank, for example, produces an index that attempts to measure a state’s true wealth, a combination of human capital, natural resource endowments, and foreign investments.14
At the end of the day, however, no measure of power is perfect, and none is likely to be. The best way to approach this problem is holistic: not declaring that one specific metric is the best, but rather summing up a variety of measures to ascertain how power is currently distributed in the international system. To obtain military victory, states must have sufficient technology, personnel, and economic might, along with access to critical natural resources, political will, and appropriate strategy. Economic and technological might can also be used in other ways to gain advantage in international rivalries. In short, explains political scientist Randall Schweller, “states are not placed in the top rank because they excel in one way or another. The rank depends on how they score on all categories of capabilities. They must have a complete portfolio of power capabilities.”15
DISPUTES AND DISAGREEMENTS
Given these disputes about how to measure polarity, it is perhaps unsurprising that there is no consensus on the question of whether the world is headed toward a period of bipolarity or multipolarity — or whether it will remain a unipolar system dominated by the United States. Disparities between economic and military indicators complicate the picture, and policymakers tend to rely on their favorite metrics for political purposes. Arguments about polarity today cluster around three hypotheses:
- The world is headed for a new bipolar Cold War. As academic Oystein Tunsjo argues, “No other states are within reach of the United States and China . . . within the foreseeable future, and no third state will be capable of developing a combined capability comparable to either.”16 A growing focus on the military is typical of such arguments. China has clearly matched American economic power and is an integral part of critical global supply chains; proponents argue that China’s military has now grown to match, to the point that it could compete with the United States in a direct conflict. There is still disagreement about whether that bipolarity is global or regional. The case is far stronger for bipolarity in the Indo-Pacific, although most would accept that China is in the process of transitioning from its position as a regional power to becoming a global one. Proponents of this viewpoint often focus heavily on the Cold War and look for ways in which a US-China competition might compare or contrast with the long-running US-Soviet rivalry.
- The world is slowly evolving into multipolarity. As political scientist Barry Posen puts it, “It seems plausible . . . that a prolonged period of multipolarity will occur before bipolarity reemerges, if indeed it ever does.”17 Instead of emphasizing military factors, those who believe that the world is headed for multipolarity tend to focus on economic, social, and political considerations. China and the United States are the largest economies in the world, but economic power has become diffuse in the last seven decades. Owing to its importance to global trade networks, the EU has significant regulatory power over trade and technical standards worldwide. The East Asian democracies, and, increasingly the developing world, are also major players in a globalized economy. Military strength remains important, but the United States, China, and Russia have repeatedly proven how difficult it can be to employ military coercion to achieve policy successes.18 The failure of the United States to leverage its grandiose military to defeat far smaller opponents in Afghanistan and Iraq — along with the emergence of various transnational threats — suggests an emergent multipolar system that will see a mixture of competition between larger states for the support of small and middle powers, along with cooperation between ad hoc coalitions to address global security challenges.
- Unipolarity will remain resilient. There is no real argument about the fact that American power has diminished relative to that of other countries in recent decades. The extraordinary power dividend that the United States enjoyed after the collapse of the Soviet Union in 1991 was never going to persist, and many countries have begun to close the gap, whether economically or militarily. One group of analysts argues that despite that relative decline, the world is still fundamentally unipolar. Indeed, Wohlforth and Brooks describe this as the “age of partial unipolarity,” arguing that the international system “retains many of the characteristics it exhibited in the age of total unipolarity, just in modified form.”19 To make this argument, they focus on America’s global military reach, which is as yet unmatched by any other nation. They also cite the dominance of the U.S. dollar in global markets and the lack of any viable alternatives to replace the dollar as the world’s main reserve currency. China is certainly a significant competitor to the United States, but these analysts believe that China is not a superpower: It has no comparable alliance network to that of the United States and has significant internal weaknesses, with increasing indications of a stagnating economy.20 As Europe and other traditional U.S. allies are unlikely or incapable of working with China, they would argue, the unipolar nature of the international system is likely to persist.
THE DATA
Each of these arguments is theoretically plausible, and each relies on specific metrics to make its case. But relying on any one or two metrics is liable to produce a biased result. Taking a holistic approach to power would suggest instead that consideration should be given to a combination of economic, demographic, and military factors to assess the relative power of the United States, China, and other states. The figure below highlights a number of possible metrics for consideration.
One of these is a metric created by social scientist Michael Beckley in his book Unrivaled: Why America Will Remain the World’s Sole Superpower, which combines GDP x GDP per capita. As the book title suggests, this measure provides a strong case for optimism among U.S. policymakers, comparing economic strength, efficiency, and liabilities to suggest that China has little hope of catching the United States. Yet the extent to which this metric diverges from almost every other measure of national wealth or power is also notable. One should be skeptical of any new measure that so neatly confirms policymakers’ priorities. As one reviewer of Beckley’s work notes, there’s a strong implicit assumption here that the data “. . . does not hide some inherent malaise in the U.S. socio-economic system,” something the turbulent politics of contemporary America suggest might not be the case.21 As a recent RAND report on the sources of societal competition states: “The United States might have begun to take on the familiar and disturbing aspect of a great power whose engine of social dynamism is being encumbered by stagnation and social instability.”22 Beckley’s measure — and his optimistic inferences — should be treated with caution.
Indeed, on almost every other metric, the picture is more mixed. Depending on how the GNI is assessed, China has either already surpassed the United States in economic terms or is closing the gap.23 Likewise, if one measures absolute economic performance (GDP), China and the United States are within spitting distance of each other. It is certainly true that Chinese economic statistics should be treated with a grain of salt, but few would doubt the dynamism and global reach of the country’s economy. In demographic terms, meanwhile, China has always had a significantly larger population than the United States. This helps to explain at least some of China’s higher score on the CINC index; that metric uses a variety of classic measurable factors like population, economic prowess, and energy production to assess a country’s overall military power potential.24 The index suggests the United States has already been overtaken by China in overall power terms.
Of course, one reason why CINC scores are so widely disdained is that few observers would genuinely believe that the United States was overtaken by China at the height of the unipolar moment in the 1990s. Pure population and economic figures can be misleading; on a per capita basis, for example, China remains well behind the United States. But although Chinese citizens still experience lower standards of living — China is substantially further behind the United States in per capita GDP — poverty has decreased dramatically in China in recent years. Even in terms of per capita GDP, the trend is one of relative decline for the United States: The U.S. economy is still growing, but China’s economy is growing faster.25
The World Bank’s measure of total national wealth (which includes human capital and natural resources) shows a similar trend: China is closing the gap with the United States. The Lowy Institute’s recently developed Asia Power Index — which includes measures of economic and military strength along with resources, alliance networks, and cultural influence — is perhaps the most granular of the data assessed here. It shows the United States and China remaining relatively constant in overall power terms and of fairly similar rank in power.26 Each of these indices relies on some combination of material resources to make its assessments, accepting — at least in theory – that economic and demographic trends are the raw resources that feed into economic leverage, military capabilities, and diplomatic clout.
Also notable, these metrics suggest global power is diffusing not only to China, but also to other states. If one looks at only the United States and China, then they could easily assume that the world is headed back to an era of bipolar superpower competition akin to that of the latter half of the 20th century. But as Ali Wyne points out in his book America’s Great Power Opportunity, the Cold War took place in a fundamentally different environment, one in which World War II had destroyed significant chunks of the prewar international system and where the formation of ideological blocs resulted in a largely bifurcated economic system in developed countries, along with a small group of poorer, “nonaligned” states. As a result, during the Cold War, the two superpowers were by far the most powerful entities in the international system, like binary suns orbiting each other and drawing other states to them. Measuring by CINC scores, for example, the United States and the Soviet Union controlled more than half of the world’s power resources, a proportion that rises far higher when their respective alliance blocs are included. Today, in contrast, the data suggests that power is diffusing away from superpowers toward a variety of capable, dynamic middle powers that will help to shape the international environment in coming decades. As Mark Leonard describes it, “Beijing and Washington do not enjoy the same global dominance that the Soviet Union and the United States did after 1945. In 1950, the United States and its major allies (NATO countries, Australia, and Japan) and the communist world (the Soviet Union, China, and the Eastern bloc) together accounted for 88 percent of global GDP. But today, these groups of countries combined account for only 57 percent of global GDP. Whereas nonaligned countries’ defense expenditures were negligible as late as the 1960s (about one percent of the global total), they are now at 15 percent and growing fast.”27
This data thus suggests we are entering a period of unbalanced multipolarity, an international environment in which two major powers (the United States and China) are pre-eminent, but other second-rank powers (i.e., Japan, the United Kingdom, Germany, India, Turkey, or France) are also important players.
Assessing Risk
MULTIPOLARITY, BIPOLARITY, AND WAR
Just as there is little agreement about the type of polarity that exists in today’s international system, there is also little agreement regarding which kind of power distribution would be more beneficial to the United States. Is multipolarity inherently more dangerous than bipolarity? The question is compounded by the fact that while stability in the international system is typically good for the United States, it does not necessarily follow that instability in less significant regions is actually harmful to U.S. interests.
Disagreement about this question goes back “at least as far as the Treaty of Westphalia in 1648.”28 Kenneth Waltz, the originator of modern neorealism, argued that bipolarity is an inherently stable system, while multipolarity is unstable. Bipolar systems, he posited, are more conducive to the effective balancing of power: They contain fewer opportunities for great powers to fight each other and fewer opportunities for misperception. His stance was heavily influenced by the time in which he wrote: The Cold War, though dangerous, had congealed into something more stable and less dangerous than great-power war, while the world wars of the early 20th century — both of which emerged from chaotic multipolar systems — were relatively recent in memory.
Today, many in Washington ascribe to a similar viewpoint. The Cold War ended peacefully, a historical anomaly that adds to intuitive suspicions that multipolarity is dangerous and bipolarity is more stable. But this tendency to rely on single historical cases to prove assumptions is problematic. Is multipolarity inherently less stable because of the sheer number of participants? That is the conclusion that many historians draw from the onset of the First World War. One could also extrapolate from the lack of direct power conflict during the Cold War that bipolarity is more stable. Yet citizens of Vietnam, Cambodia, or Korea would most likely dispute the notion that the Cold War was peaceful. As the late political scientist Bob Jervis put it, the Cold War, “the era of Great Power peace . . . coexisted with an extremely large number of wars in the Third World, some of them extremely bloody.”29 There are also the nuclear risks to consider: various Cold War periods were characterized by nuclear brinksmanship and existential fears.
Indeed, despite Waltz’s assertions, there are equally plausible arguments to suggest that multipolarity may be less dangerous than bipolarity. Political scientists Karl Deutsch and David Singer, for example, argue that arms races are less likely to escalate to war in a multipolar world, while Dale Copeland points to the increased wariness of great powers to start wars they may lose in a multipolar system.30 There have been peaceful multipolar systems in history: The Congress of Vienna in 1815, for example, created an entente between the major powers that lasted for almost a century. And some predictions based on the idea that multipolar regions are always unstable have proven highly inaccurate, such as John Mearsheimer’s infamous “Back to the Future” article, in which he argued that post-Cold-War Europe would descend back into fratricidal conflict with the return of multipolarity.31 The war in Ukraine, though consequential, is hardly the kind of all-against-all conflict predicted by Mearsheimer.
Still other scholars argue that unipolarity is most stable because it has the potential to suppress nascent conflicts before they pose any real threat, or as former President Donald Trump so memorably put it to journalist Bob Woodward: “I’d rather fight them over there than fight them over here.”32 Notably, Trump was in effect quoting his own generals to Woodward, implicitly accepting their argument that America’s global power base and military infrastructure had the potential to suppress conflict — or at least keep it far from the U.S. homeland. Such arguments form the backbone of much of the “primacy” school of U.S. foreign policy, whose proponents argued during the 1990s that the unipolar moment was a unique opportunity for the United States to use its bounty of power to maintain a more peaceful international system. As The Wall Street Journal’s Bret Stephens put it in 2015, “The alternative to Pax Americana — the only alternative — is global disorder.”33
We can point to three core reasons for these disagreements about polarity. In the first place, scholars often have different conceptions of “stability.” Most tend to agree that stability is the absence of a great deal of war and violence in the international system. But while some scholars argue that their preferred system prevents war broadly, others are merely arguing that their preferred polarity prevents great-power wars, a qualitatively very different assertion. Indeed, it seems logical that a system that suppresses certain kinds of wars could actually encourage other kinds. As political scientist Nuno Monteiro points out in his book A Theory of Unipolar Politics, unipolarity is likely to encourage one specific kind of war, that of “recalcitrant minor powers” or insurgents who object to the hegemon. This trend has occurred in recent years as the United States has engaged in crusading campaigns in the Balkans and the Middle East. And the data backs this assertion up: During the last 30 years, the number of interstate wars has decreased substantially, but the number of civil wars has risen markedly.34
A second problem is that polarity itself may matter less than how states respond to it. As political scientist Joseph Grieco has stated: “There are very few empirical or logical grounds to believe the polarity of the international structure influences the incidence of war or the chances for peace.”35 Instead, polarity should be thought of as interacting with other variables to form outcomes. Consider Glenn Snyder’s writing on alliances, which highlights the substantive differences between alliance politics under multipolarity and under bipolarity. Under multipolarity, for example, a country has a much broader choice of alliance partners than under bipolarity, where structure determines alignment for all but a few states. In practice, this means that one of the most basic state behaviors in international relations — alliance formation — looks quite different under multipolarity than under bipolarity or unipolarity.36
Other core issues of international relations also vary by polarity. Rising or falling states may be treated differently by their rivals depending on whether there are other threats in the system; balancing behavior becomes substantially more important under multipolarity, and wartime coalitions can look very different in multipolarity or bipolarity.37 The result is a much more complex picture. Some factors appear to make multipolarity more stable; these include the creation of defensive coalitions that make conquest far more difficult. Under bipolarity, in contrast, certain factors tend instead to produce military spending and arms races, creating a far riskier environment in which misperception or miscalculations can more easily lead to war.39
The final problem is that almost every analysis of the question relies on the Cold War as one of its central cases. Yet it is unclear whether the Cold War can really be compared to other periods of history that came before, thanks to the game-changing existence of nuclear weapons since 1945. In a nutshell: The Cold War did not end in a great-power war, suggesting that the era was more peaceful than today, at least in the European context.40 But it also took place under a set of circumstances quite unlike previous eras of history, one where both the United States and the USSR knew that any direct conflict could easily escalate out of all control. Equally, with mutually assured destruction providing an ultimate deterrent, nuclear weapons took the prospect of state death through conquest off the table.
In short, the nuclear balance of terror after 1945 represents a giant confounding variable for any understanding of polarity and stability in the international system. A multipolar system has not yet taken hold in the nuclear age; it is possible that it too would be more stable than prior iterations of multipolarity thanks to the deterrent effect provided by nuclear weapons. Indeed, Waltz himself alluded to this possibility when writing about bipolarity, noting that “multipolarity abolishes the stark symmetry and pleasing simplicity of bipolarity, but nuclear weapons restore both of those qualities to a considerable extent.”41
Ultimately, the evidence for the dangers of multipolar systems turns out to be mostly circumstantial: a coincidence of historical recency bias and the potential confounding effects of nuclear weapons. Theory, meanwhile, suggests a more balanced picture: Some risks may be higher under multipolarity (civil wars or conflicts between minor powers), while others are higher under bipolarity (arms races). Likewise, there are benefits to both systems. Under multipolarity, buck-passing and free-riding become more difficult, allowing great powers more freedom; under bipolarity or unipolarity, however, the great powers might be able to suppress or shorten wars in which they are not directly involved through increased leverage on their client states, but it is harder to pass the buck. In terms of U.S. interests, multipolarity — with its higher risk of small wars and lower risk of great-power conflict — may even be preferable.
Managing Unbalanced Multipolarity
THE DANGER OF “BIPOLAR” STRATEGIC THINKING
The data explored above suggests that — contrary to the popular narrative that China’s rise heralds a new bipolar competition — the world is entering a period of unbalanced multipolarity, suggesting the rising importance of second-rank powers such as Japan, the United Kingdom, Germany, India, Turkey, or France. The United States cannot create multipolarity or bipolarity, but in this situation of unbalanced multipolarity, it can promote and emphasize either the more multipolar elements of the international system or the more bipolar U.S.-China competition. Despite the narrowing power gap between China and the United States, particularly in economic terms, current U.S. strategy both leans into open competition with China and resists multipolarity. In practice, Washington is suppressing the capabilities and influence of allied middle powers, by perpetuating an alliance model in which the United States provides security for these states, and in which they have little incentive to develop their own capabilities. In this, Washington is leaning toward bipolar competition — not a good strategy for a multipolar world.
The Biden administration’s approach to a shifting global balance of power is clear: Bolster American leverage by building an anti-China coalition, emphasizing closer military and technical cooperation between allies across Europe and Asia, and attempting to build a global bloc of democracies — or at least of “like-minded” countries — oriented against authoritarian revisionists. As the 2022 National Security Strategy (NSS) states, “. . . we need to produce dramatically greater levels of cooperation. The key to doing this is to recognize that the core of our inclusive coalition are those partners who most closely share our interests. America’s treaty alliances with other democratic countries are foundational to our strategy. . . ”42 This approach is then paired with economic statecraft to contain China economically, undermining Chinese access to key global markets, restricting transfer of advanced technologies, and promoting “ally-shoring” to move supply chains away from China. Under Biden, in short, the United States plans to re-run the Cold War playbook, leaning into a global bipolar competition with China, attempting to restrain China’s rise, and hoping that the strength of allies and partners can compensate for America’s waning relative power.
This is a problematic strategy; China is no autarkic Soviet Union. Aside from some trade in commodities, the U.S.S.R. was largely cut off from global markets; it relied heavily on connections within the communist bloc. In contrast, China today is a key hub of the global economy, with spokes connecting it to every region and every type of regime. Politically, China may have few friends that fully share its ideology or repressive governance structure. Yet Chinese trade and investment is welcomed — and potentially indispensable — in many parts of the world, including some of America’s closest allies in Europe and Asia. Worse, a “bloc”-based strategy still relies on U.S. hard power for its primary military strength. In practice, this lessens the ability of allied states to contribute to offsetting Chinese power. It links every issue with the question of China and fails to prioritize.43 This strategy is likely to make U.S. relations with other countries China-centric, making it more difficult for policymakers to handle bilateral or regional interests that may be more important.44
Perhaps most problematical, this bipolar approach pushes countries to “choose a side.” As one recent essay in Foreign Affairs put it, “Countries will inevitably be caught up in superpower rivalry, and they will be required to step across the line, one way or another.”45 Although this argument might be plausible in a genuinely bipolar system, it is not likely to work in a multipolar order. Indeed, it is already clear that smaller states are not taking sides in the manner the Biden administration desires. Instead, they are demonstrating a capacity for selective engagement and multi-alignment, defined by Kelly Grieco and Jennifer Kavanagh as “not neutrality but rather an active decision made to build friendly ties with multiple major powers, working most closely with whichever partner best suits the country’s security and economic interests on a given issue.”46 The Biden administration‘s attempts to form blocs in Asia — or to formally link its alliances in Europe to its partners in Asia — have thus far produced mostly symbolic results rather than practical.
The clearest example of this approach and its shortcomings is the Biden administration’s “Summit for Democracy,” which has twice convened more than 100 countries in an effort to find ways to build closer ties among loosely defined democracies. Some countries excluded from the summit viewed it as a slight, undermining their relationships with the United States and perversely pushing them into the orbit of the major authoritarian powers.47 Owing to the broadly defined nature of democracy — so broad that participants could not agree upon a definition — states were pushed to develop shared policies and cooperate with other states that do not support many of their interests. The results have been paltry, consisting mostly of vague calls to action.48 Countries, including the United States, continue to selectively engage with autocracies when it suits them, undermining the basic premise of a unified bloc meant to reject authoritarianism.49
The Biden administration has also sought to create an economic bloc whose critical supply chains are insulated from China’s economy, most clearly endorsed by National Security Advisor Jake Sullivan’s call for “de-risking and diversifying” the economic relationship with China.50 The Biden administration and its allies have put forward the concept of “friend-shoring” as a way to reduce China’s role in strategically important supply chains.51 This effort, however, has enjoyed limited practical success. Though the Dutch signed on to initial high-level semiconductor restrictions on China, for example, Liesje Schreinemacher, Minister for Foreign Trade and Development Cooperation, cautioned that “the Netherlands will not copy the American [export] measures one-to-one.”52 Other policymakers have made clear that a European energy transition would be impossible without sustained trade with China. Meanwhile, developing and emerging economies continue to reap substantial benefits from their trade with China, leaving states like Brazil resistant to U.S. efforts.53 The economic incentives China can offer make it infeasible for the United States to form a large bloc of countries with unified economic policies that could meaningfully contain China.
This bipolar strategy is also costly; indeed, it actually incentivizes free-riding far more than necessary in a multipolar system.54 In a hearing on the most recent U.S. defense budget, Secretary of Defense Lloyd Austin made clear that increased defense spending was part of an effort to counter China, saying, “This is a strategy-driven budget — and one driven by the seriousness of our strategic competition with the People’s Republic of China.”55 U.S. allies recognize the willingness of the United States to increase security spending to not just defend its homeland but to increase the security of those who feel threatened by China. These countries echo U.S. concerns about China’s military expansion and the need to balance against it, without commensurate increases to their defense spending. In the case of Japan, successive prime ministers have attempted to increase already strong security agreements with the United States and have underscored U.S. concerns about China’s more assertive stance in the Indo-Pacific. They have even increased defense spending significantly; the country is now expected to have the third-largest military budget in the world by 2027. But Japan still faces a significant defense capabilities shortfall. Analysts predict that “even with Japan’s new commitments, the United States should expect its defense burden in the Indo-Pacific to remain largely unchanged for some time.”56 As the United States seeks to expand partnerships to counter China’s growing military capabilities, as in the establishment of the trilateral security pact among Australia, the U.K. and the U.S. (AUKUS), the problem of free-riding is likely to grow in Asia, much as it has in Europe over the years of U.S. commitments on the continent.
These problems are the almost inevitable result of the Biden administration trying to pursue a bipolar strategy in an increasingly multipolar world. Most U.S. partners remain willing to cooperate with China in diverse areas and are willing to resist U.S. pressure when the costs of complying with U.S. demands are outweighed by the opportunities of engagement with China. The administration’s hope to build a strong coalition of economically advanced democracies oriented against China and Russia is a high-stakes gamble, even in a bipolar world. With the international system becoming increasingly multipolar, it is a gamble that is likely to fail.
LEANING INTO MULTIPOLARITY
In contrast, the benefits of embracing the world’s burgeoning multipolarity and attempting to build a strategy around it are significant. First and foremost, embracing multipolarity — instead of focusing purely on bipolar competition with China — should lower the risk of direct great-power war, albeit at the cost of potentially increasing the number of lower-stakes conflicts. This trend should not be overblown; there were numerous lower-stakes conflicts during the bipolar cold war and even in the unipolar moment. Yet because great-power war today can escalate to the nuclear level, it is an existential threat; preventing great-power war should be among the most important goals of American foreign policy.57 A multipolar strategy — one that is not entirely built around containing China — also allows the United States to hedge against a possible future decline in its power, or against further rise in China’s capabilities. U.S. strategy should instead focus on ways to leverage multipolarity to its benefit, recognizing that putting all Washington’s eggs in one basket — relying solely on the United States to provide the military force necessary to monitor and manage in all the world’s major regions — poses a significant risk. The emergence of other capable actors, particularly in Asia and Europe, creates a backup for U.S. power; these states may not share all of America’s goals, but their fundamental opposition to Chinese expansionism makes it less likely that China will run the global table should the United States falter. The converse is also true: The embrace of multipolarity helps the United States to hedge against a future where China falters. By maintaining flexibility and increasing the number of available partners, this approach can help to prepare the United States for a future where a range of possible challenges emerge.
The authors of this assessment suggest three core policies that are essential components of a strategy better suited to a multipolar world:
1. Embrace and Encourage Burden-Sharing:
In the military realm, most of the factors that could substantially alter the trend lines of military power are liable to be driven less by underlying factors like substantial shifts in economic or demographic realities and more likely to be driven by state choices. In simple terms, a significant divergence in economic performance that would affect military power is a fairly unlikely event, but gradual increases or decreases — such as those seen in Europe after the Eurozone crisis — can move the needle more substantially. U.S. allies remain significantly underpowered militarily compared in proportion to the size of their economies; a choice by these states to spend more on defense is a much more effective way to shift the military balance than further expansion of the U.S. military footprint. Substantial increases in military spending by America’s European allies in the aftermath of the war in Ukraine, for example, could shift the distribution of power within Europe — particularly if Eastern European states like Poland spend more than their Western European neighbors — and could increase the overall level of military capabilities in the system. The same goes for increased military spending in Asia should China become perceived as more threatening than before; this trend is already emerging in Japan.58
Several U.S. allies or partners could achieve higher levels of military capability if they chose to do so; the British, French, and Germans all possess some level of global expeditionary capabilities today. Monteiro coined the term “major powers” to accommodate those states that are not expeditionary superpowers, but that nonetheless possess the capabilities to resist other states and to inflict serious harm on interveners or other states within their home region.59 Indeed, this approach is not actually an innovation in international relations; classical realists used to divide great powers into ranks. Political scientist Randall Schweller, drawing on this approach in his book on the interwar period, makes a distinction between “poles” and “lesser great powers” in the international system.60
In the absence of an external intervener, these second-rank states occupy the traditional role of great powers: They are able to compete within their region given a chance. Despite their growing share of global power, these states are typically dependent on economic prowess to achieve this rank and are underleveraged in military terms. Most of America’s Asian and European allies, for example, have the economic, demographic, or technological bases for military power, but they do not invest significant resources into their military, nor do they maintain high levels of troops under arms, thanks in large part to U.S. security guarantees. This implies that these states have significant headroom to rise further, turning their economic prowess into hard military capabilities, and moving the system closer to true multipolarity. U.S. policymakers should promote allied military investments to foster a system where the United States can reduce its military commitments without putting its security at risk.
2. Foster Economic Openness
In recent years, America has become addicted to the negative applications of economic statecraft, in particular the use of economic tools of coercion (i.e., sanctions, export controls, tariffs) to achieve foreign policy goals. These weapons have wide-ranging consequences and produce diminishing returns — becoming less effective over time — and could weaken the role of the U.S. dollar as a reserve currency in coming decades.61 Where there has been discussion of positive economic statecraft, it has focused on ideas like “ally-shoring,” a walled-garden approach to international trade that will ultimately lead to a less interconnected, more fragmented, and poorer global economy. This compounds the damage from sanctions and export controls, pushing states to de-risk and diversify away from the United States. Instead, policymakers should build a positive agenda of economic statecraft that fosters better ties between the United States and other countries. This does not necessarily mean a return to the full-blown globalization trends of the 1990s and 2000s. But more trade openness on the part of the United States could both help to build goodwill among developing countries and increase the resilience of global supply chains through diversity.
Various scholars have advocated similar approaches. Mira Rapp Hooper and Rebecca Lissner, for example, advocate for the United States to pursue a policy of economic openness in East Asia, preventing China from establishing a closed sphere of economic influence. Such an approach would enable rather than prevent smaller states from pursuing multi-vector foreign policy, ensuring that they have “political and economic freedom of action and are able to make independent strategic decisions without being forced into blocs or camps that could result in their hierarchical dominance.”62 Openness cannot be accomplished through gunboat diplomacy, or through economic coercion. Instead, U.S. policymakers should embrace the use of economic incentives, access to U.S. markets, and active diplomacy to promote the attractiveness of the U.S. model and ensure that China is not able to coerce countries into closing their economies to the United States.
One proven tool available to promote economic openness are free-trade agreements (FTAs), which should be pursued alongside lower-level trade and investment initiatives. The abandonment by the United States of the Trans-Pacific Partnership (TPP) and the Transatlantic Trade and Investment Partnership were significant setbacks in efforts to codify favorable trading terms for the United States. Eleven of the original participants in the TPP, whose economies comprise 15.6% of the global economy, went on to form the Comprehensive and Progressive Agreement for Trans-Pacific Partnership without U.S. participation. The Biden administration has been far less ambitious with its proposed Indo-Pacific Economic Framework for Prosperity (IPEF), which is curtailed by turbulent U.S. domestic politics and skepticism toward agreements focused on lowering tariffs and trade barriers. Nonetheless, it is notable how many regional states were keen to join IPEF and appear hopeful that the framework will lead to a broader trade agreement. The willingness of Asian states to negotiate the Regional Comprehensive Economic Partnership (RCEP) with China also highlights the strong regional demand for lower trade barriers and a more open international economic system.63
Domestic politics are likely to be an obstacle here, as a bipartisan drift toward economic protectionism threatens to perpetuate a tit-for-tat cycle of economic isolationism. Two of the Biden administration’s major legislative victories — the Creating Helpful Incentives to Produce Semiconductors (CHIPS) Act and the Inflation Reduction Act (IRA) — included protectionist policies that limit trade in specific sectors and have prompted reactions from U.S. allies. South Korea passed its own “Chips Act” in response, driven by fears that large U.S. subsidies would undermine a cornerstone of its economy,64 while the IRA led to several months of contentious talks between the U.S. and EU on green energy supply chains. In short, protectionism angers even close U.S. partners and could fuel deglobalization.65 Even if substantial improvements in the trade space are out of reach, simply reversing or halting existing trends could dramatically improve the U.S. ability to engage with other countries economically.
3. Maintain Flexible Partnerships
America’s Cold War strategy relied heavily on formalized and closed alliance structures to counter the similarly formalized and closed Soviet alliance structure. Today, that bipolar approach is outdated. The United States should instead seek flexible working partnerships with a variety of states on diverse issues, preserving its freedom of maneuver and ability to work broadly with many different states. Consider the example of NATO: For all the benefits and triumphs of the formal Cold-War-era alliance, its bureaucratization and formalization meant the alliance persisted long after the threat it was meant to combat — the Soviet Union — had collapsed.66 The organization underwent a prolonged period of searching for new missions in the aftermath of the Cold War, from counterterrorism to human rights promotion, most of which were ill-suited to existing membership and structure. In contrast, less formal partnerships or alignments on different topics can help to hedge against future threats more effectively because they do not lock the United States in when circumstances change. They also allow for greater flexibility to build ad hoc coalitions suited to the task at hand.
Indeed, though the United States will likely maintain its established alliances, policymakers should seek to shift toward minilateral groupings, issue-specific coalitions, and regional organizations, such as the G-20, the African Union, or the Quad.67 Although these are by no means new, they are likely to be of increasing salience going forward, enabling smaller groups of states to work on a narrower set of issues than the broad-based multilateral UN system, and increasing the odds of achieving concrete policy outcomes. Minilateral coalitions are a more organic alternative to larger alliances and are centered around shared interests. Coalitions like the G-7 have been successful in reaching ambitious agreements like the global minimum tax and coordinating the sanctions response to Russia’s invasion of Ukraine.68 The United States should maintain its position in these groups and advance them where it can, rather than attempting to transform such coalitions into broader blocs. Small and effective is better than big and ungainly.
The United States should also avoid attempts to isolate states that cooperate with U.S. rivals on certain issues. There was significant debate in Washington, for example, on how to respond to India’s continued purchases of Russian oil after the invasion of Ukraine. India’s position — described by some as “strategic ambivalence” — was in reality a deliberate choice, driven “not by abstract concerns about the integrity of the world order but by purposeful Indian calculations about how alienating Russia might undermine [India’s] security.”69 However, that is not how it was perceived in Washington: The Biden administration spent significant — and ultimately futile — effort attempting to persuade India to join the U.S. sanctions regime and stop importing Russian crude.70 Policymakers should be clear-eyed about this kind of hedging: States will often pursue their own interests, and the United States should beware of the tendency to shun or publicly denounce such actions as illiberal or against global norms. In short, in a more multipolar system, the overall U.S. approach to partnerships should be to pursue agreements on specific areas of interest that are likely to come at low cost and then attempt to use those agreements as a basis to build broader coalitions to address more challenging issues where greater compromise is needed. This approach requires that the United States recognize the limits of its coercive power in the current global system while leveraging its still-immense capabilities.
Conclusion
Although the balance of power in the international system is persistently analyzed by political scientists, this period of flux in the international system has broad implications for the United States and its policymakers. The direction of the international system will shape the ways in which states interact in the coming decades; understanding these changes is crucial for formulating a reliable and sustainable grand strategy. Unfortunately for policymakers, the study of polarity remains a hotly contested topic. Measuring power and polarity is difficult, and theorizing — or using historical cases — to assess the risks and benefits of multipolarity or bipolarity is challenging. But conversations about whether America is operating in a unipolar, bipolar, or multipolar world carry major implications for how the United States should pursue its own interests.
This paper assessed two key assumptions. First, the authors explored the idea that the world is headed toward multipolarity. The authors judge this assumption to be accurate: power is indeed diffusing toward middle powers in the international system, and the rise of China suggests the world is shifting toward a system of “unbalanced multipolarity,” in which the United States and China each holds a significant amount of power, but middle states in each region also play an important role. The second assumption the authors tested is the idea that multipolarity is more dangerous for the United States than bipolarity. Although this is often treated as common wisdom, the authors find this assumption to be false. Though the academic literature suggests that in general more conflicts could occur under multipolarity — and that international affairs might be more complex or chaotic — it does not suggest that there are more great-power wars. From the point of view of the U.S. interests, that suggests that multipolarity may actually be positive.
The authors conclude by discussing the ways in which these assumptions shape current policy debates and argue that the Biden administration is attempting to develop a strategy for a bipolar world, building blocs of friendly democracies, and trying to craft a new Cold-War-style coalition. This is the wrong approach. It encourages free-riding, cordons the U.S. market off from potential economic partners, and increases the chances of a catastrophic great-power war. Instead, the authors argue that policymakers should embrace the shift toward multipolarity and use it to American advantage, bolstering the military capabilities of U.S. partners and allies, encouraging economic openness, and maintaining flexible partnerships with many different states rather than a rigid alliance system. By pursuing shared interests with all comers and maintaining its outsized strength in key areas, the United States would be best positioned to benefit from economic ties while fostering a more efficient and sustained security.