A vigorous debate between proponents of realism and liberalism is deeply engrained in the literature on international relations. Acceptance of each of these competing theoretical traditions has varied cyclically. In conflict-ridden times realism has most often guided policymakers. During more peaceful periods, liberalism has more typically captured their imaginations. Regardless of whether realism or liberalism is ascendant, when global conditions change, so, too, do the general assessments of each tradition’s cogency.
World politics is currently undergoing an epic transformation that has rekindled the age-old realist-liberal debate. Two trends are driving this change. The first is a shift in the international distribution of power. In contrast to just over a decade ago, when the United States towered over other countries with preponderant military strength, unequaled economic might, and exceptional cultural allure, America now faces formidable rivals. The second trend is a cybertechnological revolution. Advances in computing and telecommunications have accelerated global interconnectedness, creating unprecedented vulnerabilities as covert online attacks now can be launched against anyone from almost anywhere.
These twin trends raise important questions about what precepts and principles should guide statecraft in the years ahead. Nowhere is the clamor for fresh thinking louder than in the United States, where the Biden administration, eager to move beyond the erratic impulsiveness of the Trump years, is seeking to chart a new course in American foreign policy. Liberal policy proposals will certainly abound, but recommendations based on political realism will also figure prominently in American strategic thinking, as they will in China and Russia.
Political realism has an illustrious pedigree, with an intellectual heritage that reaches back to antiquity. Among the many tributaries flowing into realist theory are insights on human nature, the internal structures of states, and the dynamics of interstate interactions, as espoused by such renowned figures as Niccolò Machiavelli, Jean-Jacques Rousseau, and Thomas Hobbes. As suggested by its diverse origins, modern realism is a rich, multifaceted assemblage of propositions and prescriptions for promoting national security and international order in a world lacking a central governing authority.
Drawing blanket conclusions from such an extensive body of thought risks reducing realism to a caricature that ignores differences among self-professed realists. Nonetheless, there are enough similarities among these individuals to extract some common themes regarding their worldview. To begin with, realists depict international politics as a relentless struggle for power among sovereign states of unequal strength. Relations among these fierce competitors ebb and flow in accordance with changes in the distribution of their military and economic might. Without a higher authority to supervise their interactions, “the strong do what they can and the weak suffer what they must,” as Athenian envoys famously told the Melians during the sixteenth year of the Peloponnesian War.
In the rough-and-tumble global arena, realists counsel political leaders to act in their national interest and rely only on themselves. Because no leader can ever be certain about the intentions of others, they all must do whatever it takes to survive. Everything is secondary to improving one’s relative power position. Whereas considerations of right and wrong influence the behavior of ordinary people in their everyday lives, reason of state (raison d’état) governs the conduct of those responsible for their country’s wellbeing. According to realists, foreign policy proceeds from strategic imperatives, not altruistic sentiments. Policymakers must distinguish between the desirable and the possible, and ultimately accept the lesser evil rather than hold out for the absolute good.
For realists, surviving in an anarchic environment requires acquiring arms and forging alliances. Only by maximizing their capabilities can states counter those who might threaten them. Prudent leaders match every increase in the power of potential adversaries, knowing that strength and resolve deter aggression. “If you want peace, prepare for war” is a time-honored maxim that encapsulates much of what realists preach about national security policy.
Many commentators argue that realism is useful for forecasting broad patterns in world affairs. Anyone at the dawn of the new millennium who had employed it to divine the future tenor of great-power politics would have said that over the next two decades the United States, China, and Russia were destined to see each other as rivals, not as partners in a harmonious, increasingly democratizing world. And, as realist theory anticipated, rather than enjoying productive, amicable relations, policymakers in Washington, Beijing, and Moscow have become deeply suspicious of one another and are jockeying for primacy.
Realism may be potent when it comes to predicting patterns in the behavior of great powers, but does it offer compelling advice when prescribing what they ought to do to promote peace and security? World order, realists assert, is a by-product of the self-interested quest for relative gains, not the result of policing by international organizations. States that fear being victimized coalesce against hegemonic threats, which produces an equilibrium that ensures the survival of all by offsetting the expansionist aims of any. U.S. President Richard Nixon once summarized this line of thinking: “The only time in the history of the world that we have had any extended periods of peace is when there has been a balance of power.” By his reckoning, “It will be a safer, more secure world with the United States, Russia and China each balancing each other.”
Visualizing the balance of power as a shifting scale, realists imagine that judicious adjustments—adding weight to the lighter side or decreasing it on the heavier side—can maintain international stability. By carefully calibrating when to increase armaments and make treaty commitments, where to intervene, and whether to grant dissatisfied states compensation, experienced leaders allegedly can dampen volatility and forestall hostilities.
While the balance of power is a central concept in realist theories about politics among nations, it is also highly controversial. Many people have complained about its ambiguity, questioned its assumptions, and doubted its effectiveness. Yet enough scholars, pundits, and policymakers have embraced the concept that it is no exaggeration to describe it as perhaps the most pervasive way of thinking about international relations. “If there is any distinctly political theory of international politics,” declares Kenneth Waltz, “balance of power is it.” Still, it is worth asking whether a theory based on the metaphor of simple mechanical scales offers a useful perspective on world politics in a complex digital age. Are the policy prescriptions derived from the history of European power balancing a reliable blueprint for preventing twenty-first-century rivalries from escalating to war?
Today’s digital age differs significantly from the eighteenth and nineteenth-century heyday of balance-of-power politics. Borders are no longer barriers. Hackers, whether employed by state or nonstate actors, have the capacity to disrupt energy grids, water treatment facilities, air traffic control systems, and anything else that is part of the so-called “Internet of Things.” They also are able to sow discord, widen political cleavages, and weaken civic institutions by flooding the social media of a country with a torrent of fictions, spurious accusations, and wild conspiracy theories. Sovereignty is now at bay, because no current government has the control that its predecessors once maintained over their internal affairs.
Unimpeded by geography, online attacks can strike anyone’s computers. Savvy hackers have the ability to conduct surveillance, extract classified information, prevent access to networks, or corrupt the integrity of operating systems. Since signs of a cyberattack may not appear until long after it was initiated and a meticulous forensic investigation is needed to attribute responsibility to the perpetrator, a target country’s digital infrastructure could be degraded surreptitiously by a wily foe in advance of an anticipated confrontation.
The national security implications of cyber warfare are enormous. Consider outer space, which is now recognized as a pivotal war-fighting domain. With the great powers increasingly relying on space-based platforms to monitor enemy movements, communicate with their earth-bound military forces, and provide targeting coordinates to precision guided munitions, protecting orbiting satellites is essential. To be sure, satellites are vulnerable to kinetic threats, such as missiles and space mines, as well as to directed-energy weapons, such as lasers and particle beams. However, a cheaper, less obtrusive way to nullify these vital assets is through a cyberattack that severs their links to control stations on the ground. Once its electronic connections are incapacitated, any country that relies on satellites for reconnaissance, navigation, and communication would find its military seriously weakened, essentially eliminating the option of taking coercive action in a face-off with a rival.
The national security implications of cyber warfare are enormous. A similar problem bedevils automated warfare, a prospect made possible by progress in robotics, sensors, and artificial intelligence. Lethal autonomous weapon systems, which include aerial drones, submersible vehicles, and terrestrial machines that select and engage targets using pattern recognition software, may one day be able to collaborate on the battlefield without direct human supervision. According to some defense policy analysts, packs of these small, inexpensive machines could overwhelm the large, expensive military platforms upon which the world’s great powers currently rely. Here again, though, cutting-edge military technology can be disabled by artful cyberattacks. A sophisticated hacker could neutralize autonomous weapon systems simply by corrupting their programs. Even partially autonomous weapon systems—those that are not completely independent and self-governing—are vulnerable to digital assaults.
Quantum computers, which will be able to perform computations in seconds that otherwise would take conventional computers centuries, amplify the danger posed by hackers. Development of a large-scale operational version of this technology will give its possessor the ability to break standard cryptographic systems, providing that state with unparalleled opportunities to infiltrate and possibly control digital networks in a target country.
The months-long cyberattack on U.S. corporations and government agencies during 2020 highlights the exposure of even the world’s most powerful states. Widely attributed to Russia-linked hackers, undoing the damage from this massive “supply-chain attack” (the insertion of malicious code into software updates) may take years. Infected networks must be quarantined, replacements constructed, and software fixes developed. Remediation will be time-consuming and difficult. In the judgment of the U.S. Cybersecurity and Infrastructure Security Agency, the ramifications of this breach are staggering, posing a grave risk to both the private and public sectors.
Nor are powerful states vulnerable only to cyberattacks from peers. According to a declassified National Intelligence Council document released in March 2021, Iran has carried out multiple cyberoperations against the United States. Other reports have made similar disclosures about North Korea. In short, cyberweapons are “the great equalizer.” They give middle powers the means to assail larger, stronger states in ways that would have been unimaginable in the past, making traditional threat-assessment methodologies outdated .
As cyber warfare extends interstate competition from the material to the virtual world, not only does the legal distinction between peace and war become archaic but also the calculus by which relative power has commonly been determined is no longer sufficient for assessing threats. Cyber-enabled physical attacks enable states ranking low on traditional indicators of military capability to sabotage dams, fuel pipelines, and nuclear power plants in distant countries. Cyber-enabled influence operations allow states that heretofore have been deterred from interfering in the domestic affairs of their adversaries to intervene furtively, confident that anonymity in cyberspace protects them from reprisals.
New challenges require new responses. The equilibrists of yesterday were consummate Newtonians, steeped in the logic of checks and balances, and proficient at applying counterweights to lessen disparities among jealous rivals. But the chessboard on which politics among nations is now being played has become more complex than during that bygone era. Metaphorically speaking, it is larger, containing additional pieces and new players. Even states that just a few years ago were not considered formidable can now use cybertechnology to strike the world’s most prominent nations with stealth and scale.
Given this threat, government officials are likely to gravitate toward security strategies based on anticipatory self-defense. Support for national defense is firmly entrenched in international law. States are justified in preempting forthcoming attacks and resisting those that are in full swing as long as their responses are proportionate to the danger and only target combatants. Anticipatory self-defense is more expansive. It permits states to take preventive action without waiting for an imagined threat to materialize.
Pitfalls abound, however. Intelligence on an adversary’s aspirations, intentions, and capabilities is rarely dispositive. It is usually opaque, incomplete, and nuanced. Signals of gathering dangers may be obscured by background noise, a shroud of secrecy, a well-laid deception campaign, or the analyst’s own cognitive biases.
In addition to the difficulty of receiving a timely warning precise enough to justify preventive action, a more far-reaching problem exists. By legitimizing the use of force against incipient threats, anticipatory self-defense triggers suspicion, breeds worst-case analyses, and fosters the temptation to launch a first strike—all of which increase the odds of war. If cyber technology makes customary balance-of-power calculations unreliable and anticipatory self-defense is not a fungible remedy, how can states construct a durable framework of world order on a networked planet?
The difficulty in crafting such a stabilizing framework is exacerbated by the two-level, multi-party arms competition that currently is occurring. On one level, the great powers are following the standard realist script by augmenting and upgrading their conventional military arsenals. On a second level, they (along with Israel, Iran, and several other middle powers) are developing cyberweapons that have the potential to paralyze those arsenals. Ironically, advantages accruing from the former buildup are being annulled by advances in the latter, which is why nowadays “it is difficult to understand the balance of forces.”
To call attention to the problems in applying balance-of-power logic to contemporary world politics does not warrant dismissing realism altogether. On the contrary, cyber warfare renders classical realism’s recognition of the pacifying effects of a shared diplomatic code of conduct more relevant than ever. Ever since Cardinal Richelieu advised King Louis XIII of France that “it is absolutely necessary to the well-being of the state to negotiate ceaselessly,” realists have described patient, pragmatic give and take as a vehicle for advancing national interests while simultaneously mitigating international conflict. Remaining vigilant, keeping lines of communication open, and backing diplomacy with the capability to respond firmly to instances of improbity are guidelines that seasoned diplomats—realist and liberal—largely follow. To defend the nation, “the art of negotiation is not less useful than that of war,” wrote François de Callières in a prominent eighteenth-century manual on statecraft. When broached at the right moment, “a single word or act may do more than the invasion of whole armies.”
Classical realists understood that evoking trust, considering issues from the perspective of other nations, and seeking the middle ground on issues short of a vital interest was critical in preserving peace. Doggedly insisting on one’s preferences in matters of lesser importance and banking on the ability to pressure opponents into conceding routinely fails when the moment calls for cajoling and conciliation. Persuasion, compromise, and the threat of force—all are required for successful diplomacy, with the degree of emphasis given to each technique determined by the particular circumstances of the situation.
During the depths of the Cold War, classical realists gazed wistfully to earlier centuries when the great powers considered themselves competitors in a game whose rules limiting the ends and means of foreign policy were accepted by the other contestants, even when it was not expedient to do so. They recognized that commonly acknowledged rules of the road lower tension, reduce miscalculations, and decrease the risk of unintended escalation and inadvertent war. Today, leaders and policymakers ignore these insights at their (and our) peril. Without establishing rules to curb the discretion of states to define for themselves what is acceptable behavior in the virtual world, it will be nearly impossible to manage great-power competition in the future. “Absent some articulation of limits and agreement on mutual rules of restraint,” warns Henry Kissinger, “a crisis situation is likely to arise.”
Norms of restraint do not guarantee peace, but as recent research empirically documents, wars occur less frequently when consensual ground rules constrain no-holds-barred competition. Nevertheless, states, even nonadversarial ones, disagree over which norms and rules should regulate cyberspace. Despite sharing some common interests, such as curtailing criminal and terrorist activities on the Internet, their opinions diverge over other issues, including how to define a cyberattack. The difficulties in negotiating rules of restraint in cyberspace are daunting, but they are not irresolvable. What will be required is for the great powers to collaborate with big-tech firms on developing a cybersecurity regime.
Of course, restrictive norms alone will not guarantee cybersecurity. To make norms robust against failure, they must be buttressed by an enhanced national defense against cyberattacks. While the United States has formidable offensive cyberweapons with which to retaliate for strikes on critical infrastructure, its defenses are woefully insufficient to frustrate efforts by determined adversaries to infiltrate governmental, financial, and commercial computer networks. Deterrence by punishment must be supplemented with deterrence by denial.
Throughout history, it has been critical for national leaders to take seriously major shifts in the nature of warfare. Cybertechnology is the leading edge of such a transformation. The speed at which the worldwide web has become weaponized highlights the scope and significance of this change. Accurately comparing the national power of different states has always been challenging, but revolutionary changes in computer and telecommunication technologies have made stock metrics for weighing relative offensive capability problematic. Balance-of-power reasoning arose in a world of clearly delineated borders, where aggression occurred in the material rather than in the virtual realm and used physical rather than digital means. Today’s wired world, where the capacity to disrupt is as salient as the capacity to destroy, represents a sharp break from that past and thus requires a new approach to building and sustaining international order.
Charles W. Kegley is a former president of the International Studies Association and Distinguished Professor of International Relations Emeritus at the University of South Carolina, where he held the Pearce Chair of World Affairs.
Gregory A. Raymond is Distinguished Professor Emeritus at Boise State University, where he held the Frank and Bethine Church Chair of Public Affairs.
They recently coauthored Great Powers and World Order: Patterns and Prospects (CQ Press/SAGE Publications, 2021).