AMERICA’S MILITARY preeminence is eroding. As the Pentagon and defense experts are becoming increasingly fervent in insisting, there are growing challenges to the dominance of America’s armed forces. The chief culprit behind this trend is the exertion of potential U.S. adversaries, which have—in the phrase one so often hears from defense officials and military officers—“gone to school” on U.S. military technology and the contemporary American “way of war.” And they have made a good deal of progress in preparing to counter it.

China and Russia are the two major powers with which the United States might most plausibly come to blows, and both have undertaken ambitious and sophisticated military buildups specifically designed to undermine American advantages. Both took note of the awing prowess of the U.S. military machine in the Persian Gulf War and the other regional wars of the post–Cold War era. China’s resolve to narrow and eventually negate America’s edge in armed might and the coercive leverage it provided was especially spurred by the Taiwan Straits Crisis of 1995–1996; Russia’s, meanwhile, was catalyzed by the Kosovo conflict of 1999 and accelerated starting with the Georgian War of 2008. Both countries’ buildups are increasingly challenging the U.S. military’s ability to project decisive power into the Western Pacific and Eastern Europe.

At the same time, it is not only Washington’s major-power adversaries that are beginning to pose more severe problems for America’s military ascendancy. North Korea is acquiring nuclear weapons and the means to deliver them. And a range of other lesser actors, including Iran, are exploiting the increasingly accessible technologies and techniques often lumped together under the rubric of the “Revolution in Military Affairs” to seek to complicate and hobble effective American and allied power projection.

Meanwhile, the United States has been sluggish in responding to these trends—the result of a stultifying brew of budget cuts and restrictions as well as, perhaps more importantly, a stubborn unwillingness of the American political system to face the uncomfortable reality that there are indeed intensifying challenges to American military preeminence, and that such challenges require making difficult and even distasteful choices. To stay ahead, Washington will need to shift decisively to building a military designed as carefully to overcome these opponents as they design their armed forces to defeat America’s. Washington will also need to use the U.S. military more strategically to ensure its resources are not frittered away.

Yet even such changes, which to date are only faintly in evidence, are unlikely to be so effective as to recreate the uniquely favorable military advantages of the “unipolar era.” The competitors the United States is likely to face in the future are going to be wealthier and stronger than those it faced in the period of uncontested American hegemony, and these potential opponents also appear resolved to use the substantial resources at their command to undermine and, in some respects, perhaps even overtake the American military lead. China and Russia in particular are simply richer and more powerful than they were in the 1990s and seem determined, even in the face of economic difficulties, to continue investing in strengthening their armed forces in ways designed to challenge American military primacy.

Moreover, technology, the elixir of modern military strength, is much more accessible and widespread today than it was in the past. One of the cardinal principles of the successful Second Offset Strategy of the 1970s and 1980s that produced the peerless American military of the 1990s and 2000s was that the United States was home to much of the world’s technological innovation and that it could control the spread and exploitation of that technology, at least from a military point of view. But it is much harder to hoard technology today than it was in the 1970s and, while the United States continues to be the world’s leading center of technological research and development, that lead has shrunk considerably since the 1970s.

YET THESE sobering realities should not—cannot—be cause for passivity or despair. In the first place, American military preeminence remains a great good, one to be retained if at all feasible. As in the past, a United States that is uniquely powerful is also one uniquely able to use its prodigious influence to defend the international liberal order, to pacify competition and arbitrate conflict, and to draw others towards our example. An America that can wield military power decisively and confidently on its own terms is also, unsurprisingly, one more ready to do so; but a Washington that can prevail only at greater risk and cost is likely to be a more cautious actor. Such a diminution of American military might could not but tempt revisionist powers to seek to weaken or even upend regional liberal orders that Washington has labored so mightily and for so long to construct and protect.

Second, even diminished military advantages will still afford Washington with important coercive leverage. This leverage may, moreover, be sufficient even if it is more modest than what the United States and its allies could once summon. Thus, U.S. and allied efforts to retain even a narrowed degree of military superiority will be crucial, as such advantage will continue to bolster the power, credibility and flexibility of the policy of the United States and its allies; help to balance and deter powers like China and Russia; and overawe smaller threatening states like North Korea and Iran. Even a less dominant but still very strong America will remain a dauntingly intimidating force to its adversaries and a reassuring one to its allies, partners and well-wishers, and thus will be best positioned to continue playing the stabilizing primate role it has exercised since the end of the Second World War. In the absence of hegemony, in other words, primacy may be enough.

BUT THESE realities do mean that the United States is unlikely to hold on to the degree of military advantage that it once enjoyed. And the loss of this measure of superiority in turn will entail that Washington’s ability to dictate the terms of conflict in the way it once did, particularly against the likes of China or Russia, will also diminish. As a consequence, the United States will in its defense strategy and planning have to prepare to grapple with potential adversaries that can make it significantly more difficult, costly and risky for Washington to prevail and whose demands will have to be reckoned with as the price of restraining the scope and the intensity of the conflict.

In particular, China and Russia will have to be dealt with more seriously and carefully. This is true not simply because they will wield more formidable conventional militaries brandishing weapons such as highly accurate antiship ballistic and cruise missiles, increasingly powerful antisatellite missiles and jammers, and quieter and more lethal submarines, all handled by better trained and professionalized military personnel. Rather, Moscow and Beijing—and possibly Pyongyang, albeit to a markedly narrower and lesser degree—will demand such U.S. attention because they are increasingly able to couple their stronger conventional forces with survivable and diversified nuclear forces, arsenals that are very likely able to withstand U.S. attempts to destroy them, that offer at least some ability to be employed in tailored and iterated fashion, and that are capable of striking at the American homeland with catastrophic result. Consequently, these adversaries will have the ability to take on Washington over disputes close at home for them but far distant from U.S. shores while being able to do the gravest kind of harm. And that will be true no matter what military steps the United States takes.

In other words, the United States may be able to retain advantages, perhaps very great ones, in the ability to exploit or deal with escalation against China or Russia, but it will not be able to fully control the war. In the parlance of strategy, Washington will not have that degree of escalation dominance against these opponents that once would have allowed it to comfortably and confidently dictate the terms of conflict and to prevail while doing so. Military primacy will look different than military hegemony. At the very least, it will be much more dangerous and uncomfortable.

WHAT, THEN, is the defense strategy that can sustain America’s grand strategy of protecting its allies and the liberal order in an era in which Washington will no longer so easily dominate? If Washington wishes to continue to play its stabilizing role, then it must protect those within its orbit (in concert with its allies, of course). And that means it must be willing and able to deter well on behalf of its allies and partners. But how can the United States sensibly and credibly claim to do so without being able to dominate its most formidable potential foes?

This question will only become more pointed for Washington and its allies as the margin of American military superiority diminishes. For the U.S. pledge to make war and make it effectively on behalf of its far-flung allies and interests is the strategic pillar of the modern liberal order, and the pledge must be believed if it is to be influential. The United States must be able to give some sense of how it can make war against opponents who can contest U.S. military superiority in their regions and also wreak great damage on the American homeland, and how it can make such war in a way that the costs and risks of the conflict would in some reasonable sense be correlated with the gravity of the interest at stake. The United States must provide some decent answer, in other words, to the question of how it would plan to go to war for far-flung allies in Eastern Europe and the Western Pacific against the likes of Russia and China and do so in ways that would not foolishly court destruction or defeat. In blunter terms, the United States must be able to explain how it can make war in a sensible or rational way in light of the evident truism that, as Henry Kissinger is supposed to have put it, great powers do not commit suicide for allies. Without a reasonable answer to this problem, the believability of U.S. assurances that it will come to its allies and clients’ aid in extremis will surely decline, with heavy repercussions for U.S. interests and those of its allies.

By its very nature there is no easy or pat or even a very good solution to this problem. But under the reigning defense thinking of the last generation, there is probably not even a decent one. This mindset essentially presumed, when it did not overtly state, that, to be able to credibly and effectively deter on behalf of and defend its many allies and partners, the United States needed to be able to decisively dominate and defeat any potential opponent. In this era, then, Washington gave the impression through successive Quadrennial Defense Reviews and other Pentagon documents that, in order to credibly extend deterrence, if it did not elect to go to its opponent’s capital and forcibly oust a hostile regime, as it did against Afghanistan and Iraq, then it would at the very least seize control of the battlefield and overawe its adversary into a cowed submission. In this heady age, many judged this to be the minimum standard for effective deterrence.

But obviously such a standard will be more and more unrealistic and, indeed, perilously ill-suited when control of the battlefield is the very thing at issue and when actions that could prompt dramatic escalation by the opponent, such as would likely be necessary if the establishment of dominance were the goal, could well draw a retort orders of magnitude more grievous than what the Taliban’s Afghanistan or Saddam Hussein’s Iraq could mount. In other words, if the United States makes war against Russia or China without serious regard for their red lines, as the logic of dominance would dictate or at the very least strongly suggest, it risks greatly increasing the chances of both inadvertent and deliberate escalation and the use of nuclear weapons by its adversaries. Blithely adhering to the American way of war from the era of military hegemony, that is, will push conventional wars towards becoming nuclear ones.

FORTUNATELY, HOWEVER, the United States is not limited to pursuing this approach to defense strategy. For the truth is that we know that it is at least possible to effectively deter and defend without being able to dominate. This is not a novel proposition, but rather one that we have collectively forgotten. For the proof of this proposition was amply demonstrated in the success of the U.S. Cold War strategy against the Soviet Union. Throughout the Cold War, the United States and its allies faced an opponent near-universally assessed to be militarily stronger with respect to the main theater at issue—Europe—and, from at least the 1960s onwards, one that could also strike with apocalyptic effect at the American homeland. Indeed, it is worth remembering that, despite the growing prowess of U.S. military-technological might in the latter part of the Cold War, NATO commanders regularly judged well into the 1980s that Soviet Bloc forces could punch through Allied defenses in Central Europe and reach the English Channel in as little as three weeks. At the same time, the United States and its allies had no meaningful defense against a Soviet strategic attack that could have been composed of literally thousands of unimaginably destructive nuclear warheads.

Yet, despite this truly daunting strategic problem, NATO was able to deter not just an outright Soviet attack but even serious attempts by Moscow to coerce it or pick it apart. Indisputably, this was the product of a multiplicity of factors. But it was also in significant part the product of a great deal of thinking in the United States and NATO about building the capabilities needed to fight and, at least in a particular and very modest sense, win a limited war. The problem of limiting a war under the nuclear shadow and prevailing in such a conflict first came to prominence in the 1950s and was thoroughly plumbed over the ensuing years by the most brilliant strategic minds of the Cold War period, thinkers like Thomas Schelling, Herman Kahn, James Schlesinger, Kissinger and a bevy of others at places like the RAND Corporation. This type of thinking influenced and interacted with comparable deliberations within governments and was ultimately reflected in official strategies like NATO’s Flexible Response doctrine and, in the United States, the Schlesinger Doctrine of the Nixon-Ford administration, the Countervailing Strategy of the Carter years, and the “prevailing” strategy of the Reagan period. Indeed, one of the most noteworthy aspects of American Cold War defense policy, especially after the late 1960s, was the continuing commitment by the U.S. government to developing meaningful ways of fighting a limited war with the USSR.

Of course there emerged a myriad of different approaches as to how to effectively bound and fight a limited war, and, indeed, it is very far from clear that the West ever figured out how to actually reliably do this. In fact, a great amount of skepticism and caution about the ability to tolerably limit a war between NATO and the USSR was always in order, not least because there was often more in the way of rhetoric expressing the desire rather than demonstrated ability actually to control a conflict. And, at the end of the day, the West’s deterrent always fundamentally rested on the threat to escalate to the most cataclysmic levels of destruction, a point mordantly captured by Morton Halperin’s reported observation at the close of the Cold War that NATO’s strategy could be summarized as “ . . . we will fight with conventional forces until we are losing, then we will fight with tactical nuclear weapons until we are losing, and then we will blow up the world.” In other words, NATO’s strategy was always, in practice if only partially in theory, to fight a limited war only up to a certain point and in large part as a way of smoothing the escalatory path to general nuclear use, with the purpose of increasing the latter’s credibility and thus its dissuasive force against Moscow.

But while NATO never figured out how to fight and beat the Soviets while confidently controlling escalation, the fact remained that Soviet leaders clearly saw that the West, and particularly the United States, was resolved to be ready to try, and that this readiness was tied to and designed to fortify the West’s fearsome threat to annihilate the Soviet Union if it pushed too far. Thus, even if NATO could never have been at all confident that it could have limited a major war with the Soviet Bloc, neither could the Soviets. Starting a war with NATO, in other words, would have meant Moscow taking on an opponent able to imperfectly fight a limited war—and history indicates that was sufficient to deter aggression against NATO.

The Cold War shows that one can deter even an opponent far stronger (in context) and far more menacing than either present-day China or Russia, and that one can do so without dominating the foe over the interest at issue. The point is simply that deterrence without dominance—even against a very great and fearsome opponent—is possible. And the way to achieve this appears to be by showing that potential foe that one has the ability either to adequately defend oneself and one’s confederates or to impose enough damage on the adversary to make embarking on the venture prohibitively costly, while fighting the war in a way that at least stands a decent chance of limiting the war’s destructiveness. Or, in Richard Nixon’s memorable phrasing, it means being able to fight off or bloody an opponent well enough while avoiding—or at least meaningfully delaying or shifting the onus for—the awful choice of “suicide or surrender.”

RECOGNIZING THAT deterring and defending without dominance is possible is one thing. Figuring out how to protect American interests and the security of Washington’s allies in such a situation is quite another. The starting point in doing so is to recognize that Washington will have to be prepared to fight a limited war, and fight it well. In other words, the United States will need to be able to fight a war against the likes of China and Russia without prompting them to use their nuclear weapons, or use them too much.

The concept of limited war describes the reality that conflicts can be (and often are) deliberately restrained in some fashion by the combatants, usually because both sides fear the destruction that could be caused in the absence of the establishment and mutual observation of boundaries. Such limitation can be the product of deliberate, formal agreement between the warring parties, but more often is a result of implicit bargaining. Limitation can affect the ends for which the war is fought, the geographical spread of the conflict, the intensity of violence, the types of weapons employed and a range of other factors. The purpose of such limitation is to confine the scale and scope of damage in order to protect oneself, one’s affiliates, or some broader interest (such as one’s international reputation).

This concept aptly describes the dynamic that will almost certainly obtain in the event of conflict between the United States and its potential major-power adversaries, especially China and Russia. In such a war, both sides are almost without question going to want to limit the conflict. Washington and its allies will want to restrain it primarily because of their adversaries’ nuclear-weapons capabilities. At the same time, these U.S. adversaries will want to constrain such a war as well, even though they may believe they care more about the plausible stake at issue (like Taiwan or a former satellite in Eastern Europe), because they will justifiably fear suffering the full weight of American military might, ultimately including U.S. nuclear forces.

But simply acknowledging that both the United States and its nuclear-armed adversaries will want to limit any war they engage in leaves open a great deal, indeed almost everything. Broadly conceding that a war will be limited is one thing, but determining how the war will be restrained and how well prepared one is to exploit those arrangements are other things entirely—and indeed may well determine its outcome. That is, while a limited war is by definition limited, it is also by definition a war, and thus remains a contest for, if not victory—since a limited war means that objectives must be made more modest—then at least for which side will more fully achieve its more modest aims. And so, within the necessarily fragile and elastic confines of a limited war, both sides can and will jockey, bluff, coerce and fight to gain advantage.

TAKE, FOR EXAMPLE, a conflict between the United States and NATO on one side and Russia on the other arising out of a controversy involving the Russophile population of a Baltic NATO state. In such a scenario, Moscow might intervene to defend or vindicate the purportedly aggrieved minority using some of the readily deployable conventional forces it has built up in recent years and has been exercising regularly since the beginning of the Ukraine crisis. In such a case, Russia would also rely on more sophisticated forces across the border in sovereign Russian territory to provide a range of crucial missions such as air defense, long-range strike and attacks on U.S. space assets. An adequate response by the Atlantic alliance to eject Russian forces and restore the territorial integrity of a NATO member state would require, as a matter of course, the suppression or denial of at least some of these more sophisticated forces that otherwise would menace the crucial Allied—and most importantly American—aerospace and maritime forces that provide the basis for Western military superiority.

Yet, seeking to manipulate the logic of limited war, Moscow could demand that the homelands of the major powers be considered sanctuary and that the conflict be confined to the territory and airspace of the Baltic states. Or it might declare that only a narrow band of Russian territory abutting the invaded Baltic states should be considered legitimate territory for combat. And Moscow could threaten to enforce those limitations with its strategic capabilities, including its large and variegated arsenal of nuclear weapons. If NATO ignored these proposed limitations without offering a compelling basis of limitation of its own and pursued Russian forces well within Russian territory, it might trigger Moscow’s use of nuclear weapons in a way that could look like Russia was simply defending itself, shifting the onus to respond onto NATO in a manner that might make such a response seem unjustified or too risky. But, alternatively, if NATO agreed to Moscow’s proposed terms of restraint, Russia might be able to leverage such limitation to protect and exploit its crucial antiaccess/area denial capabilities. Moscow could, for instance, bring its increasingly lethal and long-range surface-to-air missile systems into and out of the combat zone as needed, removing them for protection upon notice of vulnerability and for resupply. Such stratagems could give Russia a decisive edge in the conflict, as it could use such forces to blunt NATO air attacks, potentially denying the Atlantic alliance vital air superiority over the Baltics.

A SIMILAR dynamic might take hold in the event of a U.S. conflict with China over Taiwan or territories in the East China Sea, where the People’s Liberation Army could seek to shape the boundaries of a limited war to use its increasingly advanced capabilities, including its cutting-edge air defense and antiship systems, on the Chinese mainland to hold aerospace and maritime targets at risk anywhere over or around the island of Taiwan or over the Senkaku Islands. Without suppressing such threats, the United States and its allies or partners would have little realistic hope of reestablishing decisive control over Taiwan or the Senkakus.

This sort of manipulation of the “rules” of a war would hardly be novel—indeed there is ample precedent of the careful exploitation of such constraints even in the specific instance of air defenses. The Serbs during the NATO bombing campaigns and, with more success, the North Vietnamese during the war in Indochina all exploited particular rules to protect and strengthen their defenses against U.S. air power. Indeed, so frustrating and at times effective has this technique been that many Americans have urged simply discarding the concept of limited war entirely and either pursuing total war or abandoning the imperiled interest. The United States, in this view, should only involve itself in wars it can fight without meaningful constraint, bringing to bear the full weight of its military power.

But, as enticing as this approach might seem, the proper U.S. response to an adversary’s cunning exploitation of the rules of a limited war cannot be to insist on fighting wars only in an unrestrained fashion. For this would be to invite U.S. opponents that have formidable conventional militaries and substantial nuclear arsenals to test American resolve actually to follow through on such an all-or-nothing threat by pursuing a classic “salami-slicing” approach, chopping away at U.S. interests in steps small enough to avoid initiating a massive response. Given that few U.S. interests would really justify resort to practically unrestrained warfare, this would mean that U.S. adversaries like China or Russia could slice off increasingly hearty pieces of salami. Put another way, U.S. defense strategy cannot—and certainly should not—long be based on a bluff.

INSTEAD, THE best way to deal with this problem is for the United States to become better at limited war than these potential adversaries. This means that the United States should find effective ways to fight to achieve its political objectives while at the same time trying to constrain the war with these formidable opponents. The way to do this is for the United States to be able to more effectively operate within, manipulate and exploit the boundaries of a war both sides are seeking to limit in order to attain those ends Washington deems vital. That is, the United States should be ready to strive to set or at least substantially influence the formulae of limitation in any war in which it finds itself engaged, and should be prepared to exploit them effectively, as well as any alternative plausible boundaries of a conflict. In other words, the United States should have a clear idea of what it wants the boundaries of constraint to look like in potential conflicts with Russia or China (and likely North Korea as well), and a plan for how it would advance its arguments for those boundaries. It must also have a realistic assessment as to what the limits would actually end up looking like. That is, the United States should be prepared to operate well not only under its preferred but also under the most likely parameters of a limited war. And it should have the military capabilities and, perhaps more importantly, the plans, doctrines and strategies ready to operate effectively and ultimately prevail within these boundaries.

When it comes to the Baltic States, for example, the United States and NATO should have ready their own proposal for how to limit such a war, a proposal that Moscow would find it difficult to reject but which NATO is well-prepared to exploit. NATO should also be ready to deal effectively within the confines of what seem to be the most likely boundaries of the conflict. The same holds true for the United States in the Western Pacific.

At the same time, a limited war does not end with the vanquishing of one combatant. Rather, ending a limited war means that both sides must ultimately agree to stop fighting. This implies that both sides find settlement less distasteful than further escalation, including nuclear escalation. Accordingly, Washington must have a sober and realistic sense of what it really wants and needs to achieve in any such war, for, it is vital to emphasize, prevailing in this context of a limited war of necessity must mean achievement of only some limited goal—for instance ejection of Russian forces from a NATO Baltic state or China’s backing down from an invasion of Taiwan.

This means that the United States should be ready to use these capabilities, plans and strategies to gain military advantages adequate to achieving Washington’s political objectives and then seek to push the onus of escalation—the burden of continuing and expanding the war—onto its opponents’ shoulders. In essence, the point is to be able to overcome an adversary like China or Russia within the confines of a limited, bounded conflict and then force the other side to bear the risk, the opprobrium, and the culpability for expanding or intensifying the war. Given that Moscow and Beijing would each have abundant reason to want to limit any such war with the United States and its allies and partners, shifting the burden of deepening or expanding a conflict onto them would be a very significant strategic gain. Nor would such factors constraining them be confined to perhaps dispensable considerations of international reputation and prestige, for the United States’ own reserve capabilities to counter such escalation—including, in the extreme case, its nuclear forces—would form a powerful deterrent against the opponent seeking to escalate its way out of defeat, especially given that such employment would seem more legitimate and more readily accorded with the logic of limited war if used to respond or retaliate to the other side’s escalation.

Being well-prepared to fight this kind of war has a number of implications for the kind of military the United States should be building as well as the kinds of strategies and doctrines it should be developing and adopting, In particular, it means having a military that can prevail in a limited context—that does not rely on escalation that would be foolhardy or ineffective—while retaining substantial advantages should a conflict escalate to higher, wider or more intense levels. This does not only have implications for the kind of hardware the Pentagon buys. Perhaps more importantly, it means that the Defense Department needs to develop and integrate capabilities, strategies and doctrines for effectively fighting limited wars. This won’t come easily. The Pentagon and much of the American policy community have become accustomed to the United States being able to wage wars in which it alone can set the parameters of conflict. A full generation after the collapse of the Soviet threat and after a period in which most U.S. military attention went towards “rogue” states and terrorist or insurgent groups, many in the U.S. military and the American defense-policy world have lost mastery of or even much familiarity with what it means to face a highly capable opponent able to seriously contest U.S. dominance of the battlespace. This must change—or else the nation’s deterrent power will be considerably weakened.

THE UNITED STATES must therefore ready itself to fight a limited war. Yet doing so would be no panacea. By its very nature, indeed, fighting a limited war would be an imperfect, uncertain, frustrating and perhaps extraordinarily painful endeavor. But America must prepare to do so—and do so well—if it is resolved to maintain the international order it has built and sustained in the face of increasingly powerful rivals with formidable conventional militaries and survivable nuclear forces. Refusing to prepare to fight a limited war well out of fear that escalation could not confidently be controlled would be to risk abandoning much of the world to those less scrupulous and bolder in their willingness to manipulate and bear risk. War is, after all, as Clausewitz observed, “the realm of uncertainty . . . of chance.” Refusing to prepare for limited war out of an inability to let go of the dominance America once enjoyed, on the other hand, would either court nuclear use by an opponent or risk Washington balking in the event its resolve was really tested. Few steps, then, would more persuasively demonstrate the durability and permanence of America’s commitment to continuing to play its traditional stabilizing primate role than readying itself to fight and prevail in a limited war against the likes of China and Russia.

Ultimately, the strategy of preparing for limited war reflects the wise adage that the perfect should not be allowed to be the enemy of the good. If dominance and hegemony represent perfection, then effective defense and vindication of one’s own important interests and those of one’s allies through the ability to fight limited wars well represent the good—and the latter should be an ample definition of success in an increasingly contested and perilous world. This latter criterion may not promise the ability to transform the globe through force of arms, for in limited war forswearing triumph is the price of tolerable victory. But it can promise stability, peace and space for free mores to demonstrate their superiority in an era when the nations pledged to them will no longer clearly enjoy the preponderant power they once did. For a nation predicated on the enduring appeal of liberty and the conviction that it will deepen and spread if stoutly defended, that should be a great deal.

Elbridge Colby is the Robert M. Gates Senior Fellow at the Center for a New American Security.

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