Revisionist powers are on the move. From eastern Ukraine and the Persian Gulf to the South China Sea, large rivals of the United States are modernizing their military forces, grabbing strategic real estate, and threatening vulnerable U.S. allies. Their goal is not just to assert hegemony over their neighborhoods but to rearrange the global security order as we have known it since the end of the Second World War.
We first wrote about these emerging dynamics in 2010, and then in TAI in 2011. We argued three things. First, that revisionist powers were using a strategy of “probing”: a combination of assertive diplomacy and small but bold military actions to test the outer reaches of American power and in particular the resilience of frontier allies. Second, we argued that the small, exposed allies who were the targets of these probes were likely to respond by developing back-up options to U.S. security guarantees, whether through military self-help or accommodation. And third, we argued that that China and Russia were learning from one another’s probes in their respective regions, and that allies themselves were drawing conclusions about U.S. deterrence in their own neighborhood from how America handled similarly situated allies elsewhere.
Five years later, as we argue in a new book released this month, these dynamics have intensified dramatically. Revisionist powers are indeed probing the United States, but their methods have become bolder, more violent—and successful. Allies have grown more alert to this pressure, amid the steady whittling away of neighboring buffer zones, and have begun to pursue an array of self-help schemes ranging from arms build-ups to flirtations with the nearby revisionist power. It has become harder for the United States to isolate security crises to one region: Russia’s land-grabs in Eastern Europe provide both a model and distraction effect for China to accelerate its maritime claims in the South China Sea; Poland’s quest for U.S. strategic reassurance unnerves and spurs allies in the Persian Gulf and Western Pacific.
By degrees, the world is entering the path to war. Not since the 1980s have the conditions been riper for a major international military crisis. Not since the 1930s has the world witnessed the emergence of multiple large, predatory states determined to revise the global order to their advantage—if necessary by force. At a minimum, the United States in coming years could face the pressure of managing several deteriorating regional security spirals; at a maximum, it could be confronted with a Great Power war against one, and possibly two or even three, nuclear-armed peer competitors. In either case, the U.S. military could face these scenarios without either the presumption of technological overmatch or favorable force ratios that it has enjoyed against its rivals for the past several decades.
How should the United States respond to these dynamics? As our rivals grow more aggressive and our military edge narrows, we must look to other methods for waging and winning geopolitical competitions in the 21st century.
The most readily available but underutilized tool at our disposal is alliances. America’s frontline allies offer a mechanism by which it can contain rivals—indeed, this was the original purpose for cultivating security linkages with small states in the world’s rimland regions to begin with. In coming years, the value of strategically placed allies near Eurasia’s large land powers will grow as our relative technological or numerical military strength shrinks. The time has come for the United States to develop a grand strategy for containing peer competitors centered on the creative use of frontline allies. It must do so now, before geopolitical competition intensifies.
Probing has been the strategy of choice for America’s modern rivals to challenge the existing order. Over the past few years, Russia, China, and, to a degree, Iran have sensed that the United States is retreating in their respective regions—whether out of choice, fatigue, weakness, or all three combined. But they are unsure of how much remaining strength the United States has, or of the solidity of its commitments to allies. Rather than risking direct war, they have employed low-intensity crises to test U.S. power in these regions. Like past revisionists, they have focused their probes on seemingly secondary interests of the leading power, either by humbling its weakest allies or seizing gray zones over which the United States is unlikely to fight. These probes test the United States on the outer rim of its influence, where the revisionist’s own interests are strongest while the U.S. is at its furthest commitments and therefore most vulnerable to defeat. Russia has launched a steady sequence of threatening military moves against vulnerable NATO allies and conducted limited offensives against former Soviet satellite states. China has sought out low-intensity diplomatic confrontations with small U.S. security clients, erected military no-go zones, and asserted claims over strategic waterways.
When we wrote about this behavior in The American Interest in 2011, it was composed mainly of aggressive diplomacy or threatening but small military moves. But the probes of U.S. rivals are becoming bolder. Sensing a window of opportunity, in 2014 Russia upped the ante by invading Ukraine—the largest country in Eastern Europe—in a war that has so far cost 7,000 lives and brought 52,000 square kilometers of territory into the Russian sphere of influence. After years of using unmarked fishing trawlers to harass U.S. or allied naval vessels, China has begun to militarize its probes in the South China Sea, constructing seven artificial islands and claiming (and threatening to fight over) 1.8 million square kilometers of ocean. Iran has recently humiliated the United States by holding American naval vessels and broadcasting photos of surrendering U.S. sailors. In all cases, revisionist powers increased the stakes because they perceived their initial probes to have succeeded. Having achieved modest gains, they increased the intensity of their probes.
The strategic significance of these latest probes for the United States is twofold. First, they have substantially increased the military pressure on frontline allies. The presence of a buffer zone of some sort, whether land or sea, between allies like Poland or Japan and neighboring revisionist powers, helped to reduce the odds of sustained contact and confrontation between allied and rival militaries. By successfully encroaching on or invading these middle spaces, revisionists have advanced the zone of contest closer to the territory of U.S. allies, increasing the potential for a deliberate or accidental military clash.
Second, the latest probes have significantly raised the overall pressure on the United States. As long as Russia’s military adventures were restricted to its own southern periphery, America could afford to shift resources to the Pacific without worrying much about the consequences in Europe—an important consideration given the Pentagon’s jettisoning of the goal to be able to fight a two-front war. With both Ukraine and the South China Sea at play (and with a chaotic Middle East, where another rival, Iran, advances its reach and influence), the United States no longer has the luxury of prioritizing one region over another; with two re-militarized frontiers at opposite ends of the globe, it must continually weigh trade-offs in scarce military resources between geographic theaters. This disadvantage is not lost on America’s rivals, or its most exposed friends.
The intensification of probing has reverberated through the ranks of America’s frontline allies. In both Europe and Asia, the edges of the Western order are inhabited by historically vulnerable small or mid-sized states that over the past seven decades have relied on the United States for their existence. The similarities in the geopolitical position and strategic options of states like Estonia and Taiwan, or Poland and South Korea, are striking. For all of these states, survival depends above all on the sustainability of U.S. extended deterrence, in both its nuclear and conventional forms. This in turn rests on two foundations: the assumption among rivals and allies alike that the United States is physically able to fulfill its security obligations to even the smallest ally, and the assumption that it is politically willing to do so.
Doubts about both have been growing for many years. Reductions in American defense spending are weakening the U.S. military capability to protect allies. Due to cuts introduced by the 2009 Budget Control Act, the U.S. Navy is smaller than at any point since before the First World War, the U.S. Army is smaller than at any point since before the Second World War and the U.S. Air Force has the lowest number of operational warplanes in its history. Nuclear force levels are static or declining, and the U.S. technological edge over rivals in important weapons types has diminished. The Pentagon in 2009 announced that for the first time since the Second World War it would jettison the goal of being able to conduct a two-front global war.
At the same time that U.S. capabilities are decreasing, those of our rivals are increasing. Both Russia and China have undertaken large, multiyear military expansion and modernization programs and the technological gap between them and the United States is narrowing, particularly in key areas such as short-range missiles, tactical nuclear weapons, and fifth-generation fighter aircraft.
Recent American statecraft has compounded the problem by weakening the belief in U.S. political will to defend allies. The early Obama Administration’s public questioning of the value of traditional alliances as “alignments of nations rooted in the cleavages of a long-gone Cold War” shook allied confidence at the same time that its high-profile engagement with large rivals indicated a preference for big-power bargaining over the heads of small states. The U.S.-Russia “reset” seemed to many allies both transactional and freewheeling, and left a lasting impression of the suddenness with which U.S. priorities could shift from one Administration to the next. This undermined the predictability of patronage that is the sine qua non of effective deterrence for any Great Power.
As the revisionists’ probes have become more assertive and U.S. credibility less firm, America’s frontier allies have started to reconsider their national security options. Five years ago, many frontline states expressed security concerns, began to seek greater military capabilities, or looked to offset risk by engaging diplomatically with revisionists. But for the most part, such behavior was muted and well within the bounds of existing alliance commitments. However, as probing has picked up pace, allied coping behavior has become more frantic. In Europe, Poland, the Baltic States, and Romania have initiated military spending increases. In Asia, littoral U.S. allies are engaged in a worrisome regional arms race. In both regions, the largest allies are considering offensive capabilities to create conventional deterrence. Their willingness to build up their indigenous military capabilities is overall a positive development, but it carries risks, too, spurring dynamics that were absent over the past decades. The danger is that, absent a consistent and credible U.S. overwatch, rearming allies engage in a chaotic acquisition strategy, poorly anchored in the larger alliance. Fearing abandonment, such states may end up detaching themselves from the alliance simply by pursuing independent security policies.
There is also danger on the other side of the spectrum of possible responses by frontline allies. Contrary to the hopeful assumptions of offshore balancers, not all frontline allies are resisting. Some are choosing strategies of accommodation. Bulgaria, Hungary, and Slovakia in Europe and Thailand and Malaysia in Asia are all examples of nominal U.S. allies that are trying to avoid antagonizing the stronger predator. Worsening regional security dynamics create domestic political pressures to avoid confrontation with the nearby revisionist power. Full-fledged bandwagoning in the form of the establishment of new alliances is not yet visible, but hedging is.
Seeds of Disorder
The combination of intensifying probes and fragmenting alliances threatens to unravel important components of the stability of major regions and the wider international order. Allowed to continue on their current path, security dynamics in Eastern Europe and the Western Pacific could lead to negative or even catastrophic outcomes for U.S. national security. One increasingly likely near-term scenario is a simmering, simultaneous security competition in major regions. In such a scenario, rivals continue probing allies and grabbing middle-zone territory while steering clear of war with the United States or its proxies; allies continue making half-measure preparations without becoming fully capable of managing their own security; and the United States continues feeding greater and greater resources into frontline regions without achieving reassurance, doggedly tested and put in doubt by the revisionists. Through a continued series of probes, the revisionist powers maintain the initiative while the United States and its allies play catch up. The result might be a gradual hardening of the U.S. security perimeter that never culminates in a Great Power war but generates many of the negative features of sustained security competition—arms races, proxy wars, and cyber and hybrid conflicts—that erode the bases of global economic growth.
A second, graver possibility is war. Historically, a lengthy series of successful probes has often culminated in a military confrontation. One dangerous characteristic of today’s international landscape is that not one but two revisionists have now completed protracted sequences of probes that, from their perspective, have been successful. If the purpose of probing is to assess the top power’s strength, today’s probes could eventually convince either Russia, China, or both that the time is ripe for a more definitive contest. It is uncertain what the outcome would be. Force ratios in today’s two hotspots, the Baltic Sea and South China Sea, do not favor the United States. Both Russia and China possess significant anti-access/area denial (A2AD) capabilities, with a ten-to-one Russian troop advantage in the Baltic and massive Chinese preponderance of coastal short-range missiles in the South China Sea. Moreover, both powers possess nuclear weapons and, in Russia’s case, a doctrine favoring their escalatory use for strategic effect. And even if the United States can maintain overwhelming military superiority in a dyadic contest, war is always the realm of chance and a source of destruction that threatens the stability of the existing international order. Having failed a series of probes, the United States could face the prospect of either a short, sharp war that culminates in nuclear attack or an economically costly protracted two-front conflict. Either outcome would definitely alter the U.S.-led international system as we know it.
A third, long-term possibility is a gradual eviction of the United States from the rimland regions. This could occur either through a military defeat, as described above, or through the gradual hollowing out of U.S. regional alliances due to the erosion of deterrence and alliance defection—and therefore this scenario is not mutually exclusive of the previous two. For the United States, this would be geopolitically disastrous, involving a loss of position in the places where America must be present to prevent the risk of hemispheric isolation. Gaining a foothold in the Eurasian rimlands has been a major, if not the most important, goal of U.S. grand strategy for a century. It is through this presence that the United States is able to shape global politics and avoid the emergence of mortal threats to itself. Without such a presence, America’s largest rivals would be able to steadily aggrandize, building up enlarged spheres of influence, territory, and resources that would render them capable of sustained competition for global primacy. Unlike in the 20th century, current A2AD and nuclear technology would make a military reentry into these regions difficult if not impossible.
Avoiding these scenarios should be a high priority for the United States. In all three cases—a simmering competition along Eurasian rimlands, a great power war, and a forced U.S. retreat to hemispheric defense—it is likely to be more cost-effective for the United States to prevent negative outcomes than to undo them once they have occurred. The current moment therefore represents an important and likely perishable opportunity in which to take strategic action for shaping emerging security dynamics to our advantage. Unlike the past geopolitical contests in which it has participated, the United States will not have inexhaustible resources with which to wage the emerging battle of the 21st century. Unlike in the Second World War, it cannot simply out-produce its rivals; unlike in the Cold War, it cannot outspend them and ultimately rely on better technology. Both China and Russia, despite the latter’s relative economic weakness, have been able to use the slippage in U.S. defense spending to significantly close both the qualitative and quantitative gaps with U.S. forces. Militarily, the United States will face a more leveled playing field than it has against any other rival for many decades.
The United States should avoid the error of thinking that the contest can be industrial or technological. It is first and foremost a strategic rivalry for alliances: the revisionist powers aim to weaken the rings of allies the United States has constructed over the past century, while the U.S. wants to maintain and improve them. This—namely, the system of alliances and the inherently conservative nature of America’s grand strategy—is also where the United States has a comparative advantage.
A global network of alliances is particularly important now in the age of contested primacy. In the bipolar and nuclear confrontation with the Soviet Union U.S. alliances added few material advantages, and arguably in the immediate post-Cold War period they were disposable if not for the diplomatic benefit of having multi-national forces fighting alongside American ones. Now, alliances represent a critical margin of advantage for the United States over its peer competitors.
For the United States, the contemporary advantage of alliances goes back to their original purpose of containing distant rivals arising across the Atlantic and Pacific Oceans and menacing the political plurality of Eurasia. Allies, in particular those located on the expansionistic path of the regional predators, are most valuable because they are the most effective mechanisms to maintain the geopolitical status quo. Frontline allies have the most to lose from a dramatic change in the existing order, and thus are the most motivated to sustain it. They are the first targets of revisionists, and thus are the place where the contest is occurring and will be decided. They can also benefit from the modern technological regime that allows small states to be more lethal than in previous decades, and thus can potentially turn into defensive strongholds on their own. They want to be and can be key defenders of the Western order.
The objective of U.S. grand strategy coincides with that of its frontline allies: the maintenance of the status quo. America’s geopolitical project is conservative in nature because it aims to uphold the current geopolitical order. This goal translates most immediately into holding the existing regional limes as they are, a clear benefit to our frontline allies. Additionally, relying more on these frontline allies will allow the United States to manage the security threats in multiple regions, spanning the length of the 21st century “arc of instability” from the Baltic through the Black Sea, the Persian Gulf, and East Asia. The United States cannot thwart these challenges alone and needs to refocus its grand strategy on frontline alliances.
The purpose of such a grand strategy is to strengthen the current posture of deterrence to prevent further probes by the revisionist powers. As these probes are slowly rewriting the rules of the regional orders and are redrawing the physical lines of influence on the maps, U.S. strategy must hinder this gradual but increasingly more assertive revisionism. The role of the most vulnerable allies is crucial in the success of this strategy. The underlying assumption is that, without the active American involvement in these regions, the allies will not resist the revisionist thrusts of Russia and China, either because they cannot do it effectively alone or because they will choose to accommodate the local rival. There is nothing automatic in the survival of the current international order and the resulting security of the United States.
A strategy centered on frontline alliances will be informed by three principles.
First, the United States should organize allies. Without America’s stabilizing political leadership and reassuring military presence, the various frontier regions—U.S. allies in the most exposed rimlands—are unlikely to be able to create new regional diplomatic arrangements that can serve as the immediate bulwarks to the revisionist powers. Current alliance structures are functioning but are not well suited to the nature of the challenge. In Europe, NATO, perhaps the most successful alliance in history, incorporates states with such a fundamentally different threat assessment that its cornerstone, Article 5, suggesting that an attack against one is an attack against all, is increasingly seen as just that—a suggestion. Under the NATO umbrella, there are incipient new formations, most notably of states around the Baltic Sea (Baltics, Poland, Norway, Sweden—the latter not a NATO member). A further sub-alliance can link the Baltic region with the Black Sea, by strengthening military cooperation between the two states most interested in defending the status quo: Poland and Romania. In Asia, the alliance structure inherited from the 20th century is very different, built along bilateral relationships between individual states and the United States. But several states located on China’s seaward projection of power—for example, Japan, Taiwan, Philippines, and, farther out, Australia—share parallel concerns and fears that were not present a few decades ago. This opens up the possibility of security cooperation and planning, building a new set of regional alliances. Historical grievances continue to be an obstacle but this is why U.S. leadership and presence continues to be crucial. Without it, these frontline states will maintain a posture that only timidly considers other states in their region as solid partners in the competition with China. In brief, old alliances are not to be jettisoned but should serve as foundations for new configurations that will strengthen the frontlines.
Second, the United States should arm frontline allies. Not all, but some (e.g., Poland and Japan) are openly pursuing programs of defense modernization and seeking to acquire new weapons. The United States should encourage this by speeding the process of acquiring U.S.-made platforms and by helping these countries to think through their role in the larger strategy of anti-revisionism. Frontline states should be enabled to deter their nearby revisionists, mostly by denial. Deterrence by denial involves the development of capabilities that hinder the enemy’s military advance by increasing the costs of territorial expansion and control. Relatively cheap weapons for this purpose are widely available: anti-tank missiles, precision-guided artillery, small arms, anti-air missiles. This is also politically appealing because it is clearly an effort to shore up territorial defense, creating a difficult environment for the aggressor. But there are also other capabilities that the United States should proliferate to select allies: medium to long-range missiles, drones, and, on the higher end of the spectrum, stealth planes are examples of weapons that have a longer reach and can strike within the enemy’s territory. More offensive in nature, they still serve a defensive purpose by enhancing the ability to deter by denial. The capability to strike beyond the immediate frontline inflicts costs on the aggressor and creates problems for his logistics. By targeting command and control centers and radar installations, it also can serve to blind the enemy, easing the projection of allied reinforcements toward the attacked state. U.S. frontline allies are no longer in a permissive environment in which American forces can function unopposed. These allies therefore have the greatest incentive to keep their own air, sea, and land routes open so that the United States and other states can join them in the conflict.
Well-armed allies on a frontier under assault are a strategic blessing for the United States. They can stymie the expansion of revisionist states by becoming hardened obstacles. And the current technological regime characterized by wide availability, ease of use, and relative cheapness of many lethal platforms favors such a strategy centered on arming small states. We live in the age of small states, and even non-state actors, that are capable of inflicting serious destruction and of being strategic actors on their own. Usually in U.S. policy circles the spread of lethal capabilities is seen as a source of instability, presenting a challenge to the maintenance of international order and regional security. The plethora of hostile groups and reprobate states that can destabilize their respective regions through their capacity to wield violence is undoubtedly a problem, but the trend that makes this possible has also positive connotations. U.S. small and medium-sized allies can in fact be sources of regional stability thanks to the same technological developments that are allowing challengers to be more disruptive. The United States should harness these developments to its own advantage by doing a targeted proliferation—by arming its frontline allies.
Third, the two main revisionists, Russia and China, are nuclear powers—and the smaller third, Iran, is likely to be one in the future. Their probes are occurring therefore in the shadow of nuclear weapons. Even more disturbingly, Russia has exacerbated tensions with Europe and the United States by recurrent nuclear saber rattling in the form of provocative flights of nuclear-capable bombers, large conventional military exercises ending in a virtual nuclear attack against a NATO member, and public statements threatening nuclear use. Nuclear weapons are not decreasing in importance; on the contrary, they play a greater role now than they did fifty years ago. Any U.S. strategy dealing with its frontline allies must have a nuclear component because it needs to figure out how to deter a small conventional attack (a militarized probe) under the threat of potentially rapid nuclear escalation.
The United States should therefore enhance its nuclear arsenal by maintaining and modernizing it. It needs to sustain a credible nuclear extended deterrent at a time when revisionist states are gradually pushing their spheres of influence and control closer to, if not against, U.S. allies. Moreover, it should use the limited tactical nuclear weapons at its disposal and seed them in a few of the most vulnerable and capable frontline states (Poland and Japan, for instance) under “nuclear sharing” agreements.
By organizing and arming its most exposed allies, the United States can shore up the frontier of its influence and security. The stability of these regions cannot depend exclusively on the capability and credibility of the United States—that is, on America’s extended deterrent—but has to be built on the strength and resilience of the local allies. America’s frontline on Eurasia’s rimlands requires local defense: a well-armed and well-organized limes of allies. Only by building up such allies will the United States be capable of enduring the persistent challenge of multiple rivals that are eager to impose their own orders in their respective regions.