A quiet revolution in American defense strategy is currently underway. The U.S. military is no longer focusing on combating rogue states, terrorist groups, and other deadly, albeit relatively weak, enemies. Instead, the Defense Department is setting its sights on China and Russia: great-power rivals that are contesting American military advantages and threatening to reorder the world. “The central challenge to U.S. prosperity and security is the reemergence of long-term, strategic competition by … revisionist powers,” the 2018 National Defense Strategy states.1 Deterring these rivals, and defeating them should deterrence fail, will require far-reaching changes in what the American military buys and how it fights.
The main pillar of this strategy is a new approach to force planning, which outlines how the U.S. military should be built to fight. For more than a generation, the United States maintained a two-war standard to ensure that it could defeat a pair of regional adversaries simultaneously or in quick succession. Now, the Defense Department has adopted a one-war standard geared toward defeating a great-power rival. In other words, rather than planning to win multiple medium-sized wars, the Defense Department is preparing to win a single major war against a formidable competitor, one that can match (at least in some areas) American military might. This shift represents the most significant departure in American defense strategy since the end of the Cold War, and it has tremendous ramifications for a country that still has security commitments — and security challenges — around the globe.
The one-war standard reflects serious strategic thinking and is rooted in real budgetary constraints. It is a recognition that defeating a great-power adversary would be far more difficult than anything the U.S. military has done in decades, and that losing a great-power war would be devastating to America’s global interests. It is meant to galvanize a sluggish bureaucracy to undertake the radical changes necessary to prevent this grim scenario from coming to pass. Yet, it is far more dangerous than its advocates publicly acknowledge.2
The most obvious risk of a one-war standard is that America might need to fight more than one war at a time. In fact, a one-war standard could increase this risk by tempting an opportunistic adversary to use force in one theater while Washington is occupied in another. Proponents of the one-war approach offer a number of options for avoiding a second war, if possible, or fighting it, if necessary, but these options are not promising: They would leave the United States strategically exposed, militarily overextended, or much more reliant on highly escalatory options that lack credibility. And as America loses the ability to handle challenges in more than one theater, it will also lose leverage in peacetime competitions and diplomatic crises. In short, the one-war standard exposes a serious mismatch between America’s global commitments and the military challenges it can realistically meet — a grand strategy-defense strategy gap that may prove extremely damaging in war and peace alike.
Why This National Defense Strategy Matters
At the core of every U.S. defense review is a “force planning construct,” which specifies the number, type, and frequency of conflicts that the American military must be prepared to face.3 This construct is arguably the most important element of a defense review. It establishes what the Defense Department should buy, how it should organize its forces, and what contingencies it should prioritize. In other words, it spells out what the U.S. military must be able to do, and how big and how capable it must be, to achieve the nation’s objectives.
The key innovation of the 2018 National Defense Strategy is its one-war, great-power-centric force planning construct. “In wartime,” the document states, “the fully mobilized Joint Force will be capable of: defeating aggression by a major power; deterring opportunistic aggression elsewhere; and disrupting imminent terrorist and WMD threats.”4 Of these tasks, the first — defeating great-power aggression — is also the most important. As Jim Mitre, who helped develop the strategy, writes, the National Defense Strategy shifts the Department of Defense away from planning for “two simultaneous major wars, in separate theaters against mid-tier enemies,” in favor of a laser-like focus on “defeating aggression by a [single] great power.”5 That means the U.S. military should be sized and shaped to beat China or Russia in a high-intensity war, not to defeat some combination of weaker states such as Iran and North Korea.
The one-war construct is significant because it breaks with every U.S. defense strategy of the post-Cold War era. From George H.W. Bush’s “Base Force” concept to Barack Obama’s Defense Strategic Guidance, multiple administrations have reaffirmed that the United States must be able to prevail in two conflicts simultaneously or nearly simultaneously. In the 1990s, for example, the U.S. military was structured to defeat Saddam Hussein’s Iraq without fatally compromising its ability to fight North Korea. The idea was to ensure that a bad actor in one theater could not exploit America’s preoccupation in another theater. That, in turn, was critical to the credibility of a grand strategy based on upholding stability in multiple theaters around the world. As the 1997 Quadrennial Defense Review declared, a two-war capability is “the sine qua non of a superpower.”6
The Case for the One-War Standard
The 2018 National Defense Strategy thus signals that America must reshape its military for a new era. That shift is based on four key factors. First, and most important, are strategic considerations. Unlike in the 1990s or 2000s, when America’s main opponents were non-state actors or rogue states, Washington’s chief competitors now include resurgent or rising great powers — near-peer competitors, in Pentagon parlance — that pose a serious threat to U.S. military primacy and could seriously challenge American alliance commitments in key regions.
Since the early 2000s, both China and Russia have undertaken far-reaching military modernization programs that have emphasized the tools needed to coerce U.S. allies and hold at bay American forces that would presumably come riding to the rescue. As a result, both countries now combine increasingly advanced capabilities with profound geographic advantages, given that plausible conflict scenarios would unfold in their own back yards. These factors, in turn, would require the United States to project military power into the jaws of Chinese or Russian anti-access/area-denial capabilities in order to defend local allies and partners.7
The one-war construct is significant because it breaks with every U.S. defense strategy of the post-Cold War era.
This challenge is far more severe than anything the Defense Department has faced in recent decades. It will require fundamentally rethinking how U.S. forces will project power into contested environments, operate without secure rear areas, cope with attacks on their supply lines and communications infrastructure, and prevent a numerically superior adversary from overrunning exposed allies and partners before America can mount an effective response. It will undoubtedly demand a very different type of force than the one that thrashed Saddam Hussein in 1991 and 2003, conducted stability operations in Iraq and Afghanistan, and has chased terrorists around the greater Middle East since 2001.8 And because the consequences of losing a conflict against China or Russia would be so damaging — from fracturing alliances to causing unfavorable shifts in regional balances of power — the United States must ensure that it can defeat these countries should conflicts erupt. From this perspective, shifting to a great-power-centric force planning construct reflects a frank acknowledgment that America now lives in a very different world.
The strategic argument is reinforced by resource considerations. The fact that America faced relatively weak rivals during the post-Cold War era made it plausible, at least in theory, for the Defense Department to defeat more than one at a time.9 Today, however, a conflict with either China or Russia would consume the vast majority of America’s global combat power as well as critical enablers such as airlift and sealift (its ability to move forces and materiel into key theaters via air or sea). As a result, the United States simply cannot defeat two rivals — whether two great powers or one great power and one weaker power — simultaneously or nearly simultaneously with the resources at hand. Indeed, it is not clear whether the Department of Defense can even execute the one-war standard outlined in the National Defense Strategy with the resources available to it.10 In this sense, anything beyond a one-war standard defies the laws of budgetary physics.
The shift to a one-war standard also reflects bureaucratic considerations. For years, U.S. officials — including several secretaries of defense — have understood that great-power competition is returning.11 And for years, bureaucratic inertia has kept the Department of Defense from adapting as rapidly as it should. Key Defense Department stakeholders have often prioritized capacity (the size of the force) over new and disruptive capabilities, while clinging to legacy systems that are becoming less relevant for great-power conflicts.12
The one-war force planning construct thus serves as a bureaucratic blunt instrument. It is an unmistakable signal to actors within the Pentagon that the department must fundamentally change what it buys, how it trains, and where it focuses its attention and resources. Dean Acheson once wrote that the true purpose of NSC-68, another landmark statement of U.S. defense strategy, was “to so bludgeon the mass mind of ‘top government’ that not only could the President make a decision but that the decision could be carried out.”13 The one-war standard aims to achieve something similar within a large and unwieldy Department of Defense.
Finally, there is the influence of historical trends. If the one-war standard marks a departure from post-Cold War defense planning, it is nonetheless part of a longer-running pattern. Since the mid-2000s, the Defense Department has been gradually moving toward less expansive defense strategies in response to resource constraints and the growing difficulties of war.
In the early 2000s, the U.S. military was sized to defeat aggression in one theater, while also pursuing forcible regime change in another theater and conducting multiple, smaller operations elsewhere — all of which added up to a highly ambitious, “two-plus war” standard.14 By 2012, budget cuts and the sobering experiences of Iraq and Afghanistan had led the Obama administration to undertake a subtle retrenchment. Obama’s 2012 Defense Strategic Guidance called for an ability to defeat aggression in one theater while simply imposing “unacceptable costs” in another theater — a lesser, “two-minus war” standard.15 The one-war force planning construct then emerged after years of relative defense austerity, and as Chinese and Russian modernization made the Defense Department’s “pacing threats” far more formidable than before.16
The shift to a one-war standard was thus not undertaken lightly. It rests on a set of powerful and, in many ways, reasonable considerations. The trouble is that the National Defense Strategy also carries with it a great deal of risk and offers few solutions for how to manage it.
Can America Avoid a Second War?
The most obvious risk of a one-war standard is that the United States could confront two or more conflicts at the same time. This is hardly far-fetched given that the United States currently faces at least five potential opponents — China, Russia, North Korea, Iran, and several major terrorist organizations — across three separate theaters — Europe, the Middle East, and the Indo-Pacific — in addition to the possibility that unexpected events or crises, such as a massive chemical weapons attack in Syria, a civil war in Venezuela, or a natural disaster at home or abroad, could require the use of the American military.
A two-war scenario could occur organically, with two crises escalating to conflicts more or less independently, which happened in 1965 when the United States invaded the Dominican Republic to avert a feared Communist takeover at the same time as it was escalating its involvement in Vietnam. Alternatively, the fact that the United States has a one-war standard could actually make a two-war scenario more likely. If American troops were involved in a major contingency but the United States lacked sufficient reserves to fight other rivals, then revisionist actors might see a window of opportunity to alter the status quo in their favor and jump through it while they had the chance.
In either case, Washington would face the unenviable dilemma of either sending whatever forces were available to a second theater, even if they were outmatched, or allowing a major challenge to go unanswered. Proponents of a one-war standard are not blind to the possibility of simultaneous conflicts. But they downplay this danger with arguments that all have serious limitations.17
If American troops were involved in a major contingency but the United States lacked sufficient reserves to fight other rivals, then revisionist actors might see a window of opportunity to alter the status quo in their favor and jump through it while they had the chance.
The first argument holds that America can avoid a second war by dominating the first war. The Department of Defense’s ability to prevent opportunistic aggression, the thinking goes, ultimately rests on the battlefield effectiveness of U.S. forces. Hence, demonstrations of strength are the key to deterrence. If those forces perform well enough in the initial war, and if they win quickly enough to avoid being tied down for too long, they will discourage potential challengers from starting another conflict.18 For example, if China attacked Taiwan, and if Washington intervened and quickly achieved a decisive victory, then leaders in Russia, Iran, North Korea, and elsewhere would surely hesitate to exploit the situation, fearful that they would meet the same fate. In other words, the dreaded window of opportunity for American adversaries would never open or would quickly slam shut. And because the ability to deter a second contingency turns on the outcome of the first, there is a clear rationale for focusing relentlessly on acquiring the capabilities and competencies needed to win one major war, rather than sustaining the capacity needed to fight two.
The demonstration argument is intuitively plausible, but also problematic. After all, demonstrations cut both ways: They can reveal weaknesses as well as strengths.19 Even the most effective force can experience human errors, suffer technical failures, and take losses that tarnish its image of invulnerability. At the very least, its performance will divulge information about its preferred methods of operating as well as its tolerance for risk, which watchful rivals might use to their advantage.
In addition, the strengths that U.S. forces would showcase in this scenario may not be relevant to other threats the country faces. Like earlier strategic reviews, the 2018 National Defense Strategy calls for the United States to deter aggression. But aggression comes in many different forms, from large-scale military campaigns to less overt gray-zone provocations.20 The demonstrated ability to thwart one form of aggression may not translate into effective deterrence against others. To return to the previous example, stopping a Chinese conventional assault on Taiwan does not necessarily prove that the Department of Defense could defeat a Russian paramilitary incursion in Eastern Europe. Moreover, success in dealing with one type of challenge might simply convince a rival to undertake another. Finally, and most important, even if the United States won the first war, victory against a capable state rival would almost certainly take a heavy toll. Because the U.S. military relies on highly skilled personnel that cannot be replaced easily and highly complex platforms that cannot be reconstituted quickly, even modest losses would seriously hamper the Defense Department’s ability to take on another adversary in short order.
A second argument holds that the United States need not deter a second war because it can simply choose to delay its military response and fight that second conflict after it has wrapped up the first. From this perspective, America’s most important consideration would be to concentrate on the business at hand — namely, winning the war that is underway rather than spreading U.S. forces too thin by trying to fight a pair of wars at once. After the United States has defeated Russia’s bid to dominate the Baltic states, for instance, it could turn its attention toward defeating Iranian aggression in the Persian Gulf or meeting a Chinese challenge in the South China Sea — with the understanding that it would have to roll back some gains that the second adversary made while America was otherwise occupied.
The delay argument also makes sense at first glance. The ability to fight conflicts sequentially instead of simultaneously might keep opportunistic aggressors in check because they know they will be on the receiving end of a U.S. response eventually. Yet, the virtues of postponing intervention are not as clear-cut as they might seem.
Opting for delay risks allowing an opportunistic aggressor to successfully alter the status quo in ways that could be difficult to reverse. Indeed, National Defense Strategy advocates make a compelling case for the virtues of denial — that is, a conventional defense strategy that emphasizes disrupting and degrading enemy operations so that an adversary never achieves its aims in the first place — because the political and military costs of trying to restore the status quo ante after an opponent has secured its objectives are likely to be far higher.21 But delaying intervention takes denial off the table, unless the United States is fortunate enough to face a particularly inept second aggressor that fails to make gains even while unopposed by American forces.
An even bigger limitation, however, is that the delay argument only makes sense when the first war is also the most important war — when it is a conflict against China or Russia, rather than against Iran, North Korea, or some other, lesser threat. In this case, the dangers of failing to win the first war would almost certainly outweigh the dangers of allowing aggression in a second theater to go temporarily unanswered. For instance, if the United States were fighting China and Iran tried to take advantage of the situation, few would disagree that Washington should focus on dealing with Beijing and only turn its attention to Tehran later.
The more significant concern is that swearing off wars against certain opponents comes perilously close to abandoning deterrence altogether.
That calculus would be scrambled, however, if the situation were reversed. If the United States was fighting a regional power like Iran when a great power like China decided to initiate a crisis, the second war would be far more strategically consequential than the first, and the costs of delay would probably be far higher. That would leave the United States with the choice of either breaking off the first conflict and fighting the second with a weakened force, or somehow trying to juggle two wars with a force designed for one. Put another way, opportunistic aggression may not be a challenge that America can afford to ignore.
The final argument holds that the United States can avoid this dangerous situation — in which fighting a regional power undercuts America’s ability to fight a great power — by exercising strategic discipline. That is, it can simply choose not to intervene at all against hostile regional powers, keeping its powder dry in case great-power conflict breaks out.22
There are, of course, many reasons to be cautious about committing U.S. forces against second- or third-tier opponents in lower-priority theaters. Adapting for an era of great-power competition certainly requires stricter prioritization and the more judicious application of limited resources. Yet, the discipline argument still falls short, and not solely because the U.S. track record when it comes to focusing on China and Russia (as opposed to, say, North Korea and Iran) is already mixed at best. The more significant concern is that swearing off wars against certain opponents comes perilously close to abandoning deterrence altogether. No one should want to see the United States spend blood and treasure unnecessarily, or in ways that weaken its overall strategic position. Yet, simply refusing to use force against second-tier opponents absent some truly extreme provocation signals that America cannot and will not respond forcefully to aggression short of the outrageous. That, in turn, is a recipe for the dissipation of U.S. influence and the destabilization of areas, such as the Korean Peninsula and the Middle East, that still matter to American security.
Strategy in the Second War
If demonstrations, delay, and discipline cannot adequately reduce the danger that America will find itself confronting simultaneous conflicts, the Defense Department will need other methods of deterring or, if necessary, fighting multiple wars at once, unless it is ready to walk away from longstanding U.S. commitments. The public version of the National Defense Strategy hints that the United States can indeed deter multiple rivals within the framework of a one-war standard but doesn’t provide much detail on how.23 There are three obvious options, however, none of which are mutually exclusive, but all of which have serious liabilities.
The first option is outsourcing deterrence and warfighting by relying on allies to preserve the status quo in their home regions. From the Nixon administration’s “Twin Pillars” approach in the Middle East, which depended on Saudi Arabia and Iran as the first line of defense against regional instability and Soviet encroachment, to the recurring attempts to court India as a bulwark against Chinese expansion in South Asia, the United States has often tried to reduce the burdens of upholding regional orders, especially (but not exclusively) at moments when its relative power seemed to be in decline.24 Likewise, the National Defense Strategy calls for the United States to “strengthen and evolve [its] alliances and partnerships into an extended network capable of deterring or decisively acting to meet the shared challenges of our time.”25 From this perspective, the Trump administration’s efforts to compel allies to increase defense spending and to sell additional arms to strategically important states could lay the foundation for better burden-sharing or burden-shifting in the future.26
Calling on allies and partners plays on America’s chief geostrategic advantage: its unrivaled global network of security relationships. Moreover, U.S. allies and partners from East Asia to the Persian Gulf to Western Europe certainly could enhance their military power in ways that would make them more resilient to coercion and aggression.27 Yet, there are many reasons to be skeptical that allies, in any of these regions, would be willing and able to deter local threats largely on their own. Between resource constraints, domestic political debates, divergent threat perceptions, and historical feuds that prevent allies from working closely with one another, there are enough barriers to believe that true outsourcing is not a viable option. Indeed, the reason the United States has not been able to extricate itself from commitments in these theaters — despite periodic efforts over the past 70 years to do so — is precisely because those allies and partners have not been able to summon the collective will and capability to confront the threats they face without the promise of American military support. And even if the United States could theoretically convince its allies in, say, Europe and the Persian Gulf to develop vastly improved military capabilities by announcing that America would not necessarily come to their aid in a crisis, doing so would risk forfeiting the other great benefit of U.S. security commitments and force deployments — the suppression of conflicts between American allies and partners, which has contributed enormously to the relative global peace of the post-World War II era.28
The second strategic option is escalation: placing greater reliance on nuclear weapons to deter or fight an opportunistic aggressor. On its face, this would seem to be a natural way of compensating for the limits of U.S. conventional military strength.29 The United States retains a large nuclear arsenal to provide escalation dominance over at least some of its rivals, as well as to make credible its extended deterrence guarantees to allies. Since 1945, America has always reserved the right to use nuclear weapons first during a conflict. Therefore, it should be well positioned to use nuclear forces to deter threats in a second theater or fight a second contingency if deterrence fails.
Yet, escalating is even more problematic than outsourcing. A credible escalation strategy requires pronounced nuclear advantages over potential enemies. Unfortunately, Washington does not have the same advantages it did as recently as the early 2000s. China and Russia — as well as other countries — have been developing and fielding new nuclear systems and, in some cases, expanding their nuclear arsenals. The United States is just now beginning to recapitalize its aging nuclear arsenal after many years of deferring modernization. Moreover, there are questions about its ability to fund and field newer capabilities before older capabilities must be retired and about whether planned modernization programs will actually produce new advantages given countervailing steps by some opponents.30
A strategy of escalation would face other credibility problems, as well. If there were doubts about America’s willingness to use nuclear weapons to prevent the Soviet Union from overrunning Western Europe (and overturning the global balance of power) during the Cold War, it is presumably harder for allies or adversaries to believe that the United States would start a potentially cataclysmic nuclear war to defend far less significant territories such as Estonia or Taiwan today.31 Using nuclear weapons first in a conflict against China or Russia would require a fundamentally different approach to deterrence and warfighting — one for which American leaders have not sought to prepare the American public or world opinion. Even the credibility of first use against non-nuclear armed states would be suspect in many scenarios. The United States has worked for several decades to narrow the conditions under which it would employ nuclear weapons, counting instead on its conventional military power to deter aggression, and has shed most of its tactical and theater nuclear capabilities, which could leave it in the position of relying on “massive retaliation light.”32
In sum, unless the United States is willing and able to reverse prior efforts to reduce the role of nuclear weapons in its defense strategy, unless it can rebuild its strategic arsenal over a relatively short period of time, and unless it can identify realistic limited nuclear options (beyond the changes advocated for in the 2018 Nuclear Posture Review) that allow it to counter conventional threats or inflict selective punishment — each a tall order in its own right — escalation is probably not the answer.33
The third and final option is mobilizing: increasing the capacity of the joint force to manage threats after they materialize. If, for instance, the United States were to face the strategic nightmare scenario — simultaneous conflicts against China and Russia — it could undertake a World War II-style mobilization that would dramatically expand the military and provide whatever level of resources was necessary.34
Yet, the prospect of mobilization raises questions of will and ability. If Russia and China both launched major, unprovoked assaults on U.S. interests, a large and rapid mobilization of America’s manpower and industrial resources might be politically feasible. It is not a given, however, that the public would support such a mobilization to fight limited wars that began in ambiguous ways in theaters thousands of miles from American shores. Adversaries, knowing this, could calibrate their aims and actions to increase the probability that U.S. mobilization and military intervention would be controversial at home. China, for example, could issue an ultimatum against Taiwan without actually firing a shot or use its coast guard vessels rather than its navy to provoke Japan in the East China Sea, while Russia might seize a small piece of territory in a Baltic state rather than occupy an entire country, and might use unmarked soldiers or contractors rather than uniformed military personnel. Under these conditions, would there be significant popular and political support for a U.S. military response, let alone for marshaling the extra personnel and materiel necessary to fight a pair of wars?
Even if the case for intervention were clear cut and support for mobilization high, a variety of factors — including years of consolidation among leading defense companies, low production rates of high-end weapons, and increasingly complex yet fragile supply chains — suggest that the industrial base is not equipped to ramp up production on short notice.35 The United States can and should take steps to improve its mobilization capacity, just as it should modernize its nuclear arsenal and push its allies to fortify their defenses. But it probably cannot rely on these measures as substitutes for conventional forces-in-being.
Risk-Taking, Decision-Making, and the Military Balance
Beyond the military challenges that a one-war standard introduces are a set of broader diplomatic and geopolitical challenges. The military balance — and the military options to which a country can realistically resort in war — invariably shapes risk-taking and decision-making in peacetime.36 Here, too, the one-war standard introduces deep challenges for a superpower that must manage peacetime competition and diplomatic crises in multiple theaters at once.
Most of these implications flow from a basic imbalance between U.S. defense strategy and the larger grand strategy the National Defense Strategy is meant to support. The 2017 National Security Strategy makes clear that America is not retrenching geopolitically: It remains committed to its longstanding, three-theater grand strategy that aims to preserve stability and uphold favorable configurations of power in Europe, the Middle East, and the Indo-Pacific.37 Yet, any grand strategy rests on a foundation of military power, and the National Defense Strategy essentially acknowledges that Washington has only one theater’s worth of military power should war break out. If it is true, as Defense Department planners have long argued, that the ability to respond to more than one challenge at a time is critical to America’s global credibility and confidence, then a one-war standard will presumably affect the calculations of policymakers in the United States and around the world.
Consider the view from Washington. If U.S. officials know that fighting Iran or North Korea will fatally undermine the Defense Department’s ability to defeat China or Russia, they will be less likely to act assertively — through military measures or even diplomatic or economic sanctions that risk escalation — in response to provocations by Tehran or Pyongyang. By the same token, if an American president understands that a conflict with either China or Russia would eat up the country’s global combat power, she may be less willing to risk war in a crisis over Taiwan, the South China Sea, or the Baltic for fear of leaving America strategically exposed in the Middle East or Northeast Asia. The United States could unintentionally end up not with a one-war standard but a zero-war strategy, because committing the American military anywhere poses too great a risk to Washington’s commitments and interests everywhere.38
To be clear, the argument here is not that an American president would decline to respond to a clear-cut, large-scale assault on U.S. interests — such as a North Korean missile attack on Japan or America itself, or an outright Russian invasion of Estonia or Poland. Nor is it that fighting a war against Iran or North Korea (much less China or Russia) is a desirable outcome. The argument is that American leaders will feel less confident that they can assert the nation’s interests vigorously in a crisis or competition that falls short of outright war, that they will be more hesitant in committing U.S. forces abroad, and that this will inevitably undermine Washington’s geopolitical leverage in dealing with great powers and lesser powers alike. U.S. policymakers might be self-deterred from issuing coercive threats against Iran for fear of compromising the Defense Department’s ability to defeat China. Or they might just have to bluff — issuing coercive threats that can’t be carried out without inflicting unacceptable costs on America’s broader global posture — with all the accompanying dangers if that bluff is eventually called.39
Indeed, the fact that the United States is executing a three-theater grand strategy with a one-war military will not be lost on other countries. In an extreme scenario, American competitors could exploit U.S. intervention in one theater to roll the iron dice in another, or they could lend support, whether covert or overt, to Washington’s adversary in order to bleed U.S. forces and further deplete their ability to intervene elsewhere.40 Short of such measures, American competitors could use the conflict as a source of diplomatic leverage against the United States — taking advantage of Washington’s weak bargaining position to force U.S. officials to accept a nonviolent change in the status quo.41
The United States could unintentionally end up not with a one-war standard but a zero-war strategy, because committing the American military anywhere poses too great a risk to Washington’s commitments and interests everywhere.
An overstretched superpower could also lose leverage vis-à-vis its rivals before even a single conflict is underway. If Washington faces so much as a realistic prospect of war with Russia or China in the coming years, North Korea or Iran may feel emboldened to push for gains below the threshold of outright conflict, confident that U.S. officials will not escalate because the Defense Department cannot handle multiple challenges at once. Russian leaders might perceive that they have greater geopolitical running room in Eastern Europe or the Middle East if the United States finds itself in a crisis, or facing higher tensions, with China. Meanwhile, the calculations of U.S. allies and partners will also be affected. The National Defense Strategy is premised on helping regional allies and partners become more assertive and self-reliant so they can decrease the overall burdens on the United States.42 But American friends in the Persian Gulf or Western Pacific may instead feel forced to draw in their horns at a time of U.S. involvement in a faraway theater, lest they end up in one war while Washington is preoccupied with another.
In short, every global power — from the British Empire at its peak to the United States during the Cold War — faces the same basic dilemma: It cannot possibly meet all of the threats to its interests if those threats manifest at the same time.43 The one-war standard sharpens this timeless dilemma by widening the gap between the number of theaters in which the United States is committed and the number of theaters in which it can plausibly respond. The wider that gap becomes, the more it will influence the decisions of the United States and other countries in war and peace.
It is true, of course, that there are also clear risks associated with not focusing intently enough on being able to defeat a single great-power adversary. If America cannot credibly claim that it can rebuff Russian or Chinese aggression because it has remained preoccupied with lesser threats, then U.S. geopolitical leverage in Europe and the Western Pacific will decline precipitously — as will America’s ability to deter conflict. Yet, in buying down this particular type of geopolitical risk, the one-war standard threatens to expose the United States to all the other risks that come from having a one-theater force in a three-theater world.
A Time for Choosing
The architects of the National Defense Strategy are right about one thing: The Defense Department cannot go back to business as usual if that means focusing on relatively weak rivals at the expense of transforming the military to deal with hostile great powers. A world in which the United States has the force structure to defeat North Korea and Iran but not the advanced capabilities and concepts needed to defeat China or Russia would be incredibly dangerous from the perspective of American alliances and geopolitical stability. To remain relevant in today’s global environment, any defense strategy must keep rival great powers in the crosshairs.
Yet, the Defense Department’s current approach is far riskier than it might appear. Pairing a one-war defense standard with America’s existing global commitments is a recipe for disaster. Without adequate military muscle to back up its threats and promises, Washington could grow so reluctant to uphold its security commitments that they become nearly worthless. Or it could try to enforce those commitments and fail. In either case, adversaries would have more incentives to challenge the status quo, while allies would have more incentives to look out for themselves. The United States could find itself fighting conflicts for which it is not prepared — or sliding, by default rather than by design, into a less ambitious grand strategy that compels it to stay on the sidelines as American influence plummets and international order erodes.
There is no magic formula for solving this problem. There are steps the United States can take to narrow the gap between its defense strategy and its global commitments: pushing allies to strengthen their defense capabilities, modernizing America’s nuclear arsenal and developing more limited nuclear options, improving the country’s mobilization base, and others. But Washington should be adopting many of these measures under any defense strategy, and, moreover, they still might not fully close the gap that the National Defense Strategy reveals.
Ultimately, the shift to a one-war standard is bringing the United States face-to-face with a more fundamental choice: It can pare back its commitments to bring them into alignment with existing resources, or it can increase its resources to better meet existing commitments. It is unlikely that the Defense Department will ever get back to the comparatively halcyon days in which it prepared for two wars against regional powers that it would almost certainly win. It is just as unlikely, absent some NSC-68-style explosion in defense spending, that the Defense Department can secure sufficient resources to fight multiple wars against great powers, let alone to fight three or more conflicts simultaneously. The last time the United States had anything like a 2.5 war standard, it was spending roughly 8 or 9 percent of GDP on defense — more than twice the amount of GDP it is spending today.44 Yet, additional funding could allow the Department of Defense to reduce the risks it is starting to run — and therefore to rely less on outsourcing, escalating, or mobilizing.
The United States must decide soon whether to invest significantly more resources in stiffening the hard-power backbone of its grand strategy or scale back that grand strategy to better fit its defense capabilities.
In this scenario, the Defense Department would maintain at least a 1.5 war standard: It would combine the capabilities needed to defeat a great power like Russia or China with the capacity required to also fight a regional power war at more or less the same time. This approach would require simultaneously developing the innovative capabilities and concepts needed to deal with a great-power rival and preserving (or strengthening) the force structure, sealift and airlift, munitions stockpiles, and other assets needed to do more than one thing at a time. That might not be enough to avoid the nightmare scenario of facing overlapping great-power conflicts, which would remain unmanageable without a far greater mobilization of American society as a whole. Nevertheless, it would help to deter regional-power aggression if the United States were fighting a great-power war (and vice versa), while also providing a cushion if a great-power war went worse than expected. It would not completely close the gap between America’s commitments and its capabilities, but it would narrow it and reduce the dangers it poses.
Even that would be a considerable expense, however. The nonpartisan National Defense Strategy Commission has estimated, for instance, that a force capable of fighting more than one conflict simultaneously would require at least a 3–5 percent annual increase in real defense spending over a period of at least five years. But most observers currently expect Defense Department outlays to stagnate at best and decline at worst in the years ahead.45 And money is only one part of the equation. It is now widely recognized that, in addition to new capabilities, the Defense Department also needs new ideas: novel operational concepts for fighting in contested environments. What is often overlooked is that this point does not just apply to rival great powers.46 The United States also needs more effective and efficient ways of warfare for dealing with second-tier rivals like North Korea and Iran, especially as those powers become increasingly capable.
Alternatively, the United States could undertake a more searching reevaluation of its grand strategy: It could explicitly retreat from commitments in the Middle East and make painful concessions to Vladimir Putin’s Russia in hopes of easing the hostility of one great-power rival. It could withdraw from the Korean Peninsula, counting on South Korea and other regional powers to deter or defeat North Korean aggression without significant American help, or otherwise shrink America’s global ambitions. Yet, this approach relies on heroic assumptions about the possibility of diplomacy turning rivals — particularly Russia — into friends or at least nonthreatening neutrals.47 It also contradicts the Defense Department’s own logic by asserting that Washington can pull back from key regions without jeopardizing its interests there. It is easy to say that the United States should shrink commitments to restore strategic solvency, but it is far harder to do so in a responsible way.
The flaws of the one-war standard can be thought of as the canary in the coal mine — the warning of greater perils and far sharper dilemmas to come. The United States must decide soon whether to invest significantly more resources in stiffening the hard-power backbone of its grand strategy or scale back that grand strategy to better fit its defense capabilities. What it should not do is assume that this choice between unpalatable options can somehow be avoided. The worst approach to dealing with any glaring strategic problem is to pretend that the problem does not exist.
Hal Brands is Henry Kissinger Distinguished Professor of Global Affairs at the Johns Hopkins School of Advanced International Studies, a scholar at the American Enterprise Institute, and a Bloomberg Opinion columnist. His most recent book, with Charles Edel, is The Lessons of Tragedy: Statecraft and World Order (2019). He is currently writing a book on how history can inform America’s approach to long-term competitions with China and Russia.
Evan Braden Montgomery is senior fellow and director of research and studies at the Center for Strategic and Budgetary Assessments. He is the author of In the Hegemon’s Shadow: Leading States and the Rise of Regional Powers (2016), as well as articles in Foreign Affairs, International Security, Security Studies, and the Journal of Strategic Studies.
Image: U.S. Navy