Major Stephan J. Pikner, USA, is the Army Strategist Association Secretary for the 2017–2019 board term and is studying at Georgetown University as part of the Army’s Advanced Strategic Planning and Policy Program.
After 17 years of the war on terror, the United States and its allies stand today at a grand strategic inflection point. As America concentrated on Iraq, Afghanistan, and countering violent extremism across the globe, regional powers such as China, Russia, and Iran dramatically expanded their ambitions and capabilities. Starting with the 2008 Russian invasion of Georgia, and accelerated by the global financial crisis of 2008–2009, this resurgence of great power assertiveness has been met with a certain weariness by the West. While American allies and supporters of the rules-based international order have—in many cases belatedly—woken up to the threat of systemic upheaval, the lack of a shared organizing principle has limited the free world’s response. Emerging rivals have historically focused minds and opened wallets, but today America’s military is hamstrung by competing visions and priorities.
In this emerging global security environment, the United States should modify its military structure and global posture to counter the full array of rising regional rivals and ensure the continued security, freedom, and prosperity of its allies and like-minded partners throughout the world. Through a process of deliberate security partnership and capacity-building—an approach this article dubs “complementary engagement”—the United States can maintain global leadership, adapt to today’s threats, and rebalance the burden and risk of security to reflect modern economic realities.
The departure point for this article is G. John Ikenberry’s view of the post–Cold War era as an “American-led liberal hegemonic world order,” where unrivaled U.S. strength underwrites economic growth and political liberalization through a widely accepted, voluntary, rules-based, but increasingly atrophying system. While the inherent stability of unipolarity has been debated by international relations scholars, the failure of a cohesive counterbalancing coalition to emerge as a challenge to the American-led system supports Ikenberry’s benign view of U.S. dominance.1 This does not mean that the United States and its allies do not face an array of increasingly assertive and capable threats that seek to undermine this order—as the 2018 National Defense Strategy clearly states, we are facing “increased global disorder, characterized by decline in the longstanding rules-based international order.”2 Rather, it sees these rivals as probing for weakness along the periphery, and seeking relative gains from the resultant anarchy.3 While there are many elements to the American-led, rules-based international order, this article argues the largest and most critical piece of the structure that undergirds it is U.S. military power.4 Given a range of rising regional rivals who are engaging in interstate competition, along with the continued war on terror and increasingly independent and well-armed allies, how can the United States best ensure continued security and prosperity?
To answer this question, this article begins by tracing the evolution of strategy from the end of the Cold War to the recently published National Security Strategy (NSS). Examining proposed alternatives to America’s grand strategy and the events that shaped its evolution frames the second section, which explores the current dilemma and helps differentiate today’s challenge from the previous contexts that still form the foundation for many current proposals. In the final section, this article proposes a comprehensive military structure and posture shift—complementary engagement—that better addresses the dilemma of rising regional rivals.
The Evolution of Post–Cold War Grand Strategy
The collapse of the Soviet Union prompted a broad reassessment of American grand strategy. Deep engagement, the prevailing American strategy during the Cold War, can be defined as the enduring diplomatic, informational, military, and economic partnerships with a wide range of allies and partners across the globe that underwrote sustained economic growth and regional stability in the face of communism. It enabled the West German and Austrian postwar Wirtschaftswunder and the phenomenal growth of the “Asian Tigers” in the shadow of Soviet and Chinese communism, and nurtured liberal democracy in Europe and Asia.5 Deep engagement’s critics, though, cited the high cost of maintaining this military footprint, the trap of allies shirking their defense responsibilities, and the risk of being drawn into peripheral conflicts as reasons to reassess this grand strategy in the wake of the Soviet demise.6 Several alternatives to the Cold War approach of deep engagement were posited in the 1990s. These ranged from a return to pre–World War II reclusiveness to a continuation of the expansive (and expensive) Cold War posture. This debate considered several options, broadly categorized as neo-isolationism, selective engagement, cooperative security, and primacy.7
Neo-isolationists advocated disentangling from the web of alliances and commitments across the world that was woven during the Cold War. The geographic advantages of the United States, coupled with its lack of historical rivals and overwhelming military and economic power, could allow America to safely step back from the world. Even if a threat to the United States did emerge, geography would provide a buffer to allow for rearmament, as it did in the opening years of World War II. Left unanswered by proponents of neo-isolationism, however, was the threat of nuclear proliferation among states that could no longer rely on the American posture of extended deterrence for their own security.8
Advocates for selective engagement sought to focus American power solely on geopolitically critical areas, rather than spreading it ineffectually across the globe. By prioritizing strategic regions, selective engagement “steers a middle course between isolationism . . . and world policeman.”9 The underlying security relationship between the United States and its allies would remain similar to the Cold War dynamic, but instead of seeking to contain the Soviet threat, American forces would stabilize and secure key political and economic allies.
While selective engagement supports a relatively narrow and material definition of American national interest, the option of collective security considered peace a public good that must be provided by the shared efforts of like-minded nations. Through collective action to uphold norms and punish rogue actors who undermine peace and stability, states would act in concert to deter conflict and limit its effects. Regional collective security focused on building such systems in discrete areas of the world, while the global version of the concept viewed security as a world-spanning ecosystem where no one region could be isolated. Liberal institutions would be central to overcoming the inherent collective action problems.10
Primacy—the most ambitious option considered—is a global extension of hegemonic stability theory: “Only a preponderance of U.S. power ensures peace.”11 Primacy sought to capitalize on America’s post–Cold War unipolarity through sustained investment in and use of all elements—diplomatic, informational, military, and economic—of national power. This approach would mitigate the collective action problems inherent in collective security while extending the values of democracy and free trade across the world in a way that the more limited strategy of selective engagement could not.
The debate over the fundamental nature of American foreign policy continued through the 1990s and was reflected in academic articles, policy documents, and foreign policy decisions. The final Clinton administration NSS integrated the ideas of primacy and cooperative security into initiatives that expanded the North Atlantic Treaty Organization (NATO), promoted free trade, and strengthened international cooperation against terror and weapons of mass destruction. Cooperative security’s focus on controlling illicit arms and rogue states was evident in nonproliferation cooperation with Russia, and in a nod to global collective security’s requirement for resolving and containing conflict across the world, a variety of peace-building successes in five continents were cited in the 1998 NSS as evidence of the value of sustained engagement.12
The shock of September 11, 2001, reframed the debate over American foreign policy as the defense of the homeland clearly took priority. Threads of cooperative security remained in the 2002 NSS, though now woven into the global counterterrorism effort: “Today, the world’s greatest powers find [themselves] on the same side—united by common dangers of terrorist violence and chaos.”13 The 2006 NSS continued this theme by starkly opening with the declaration that “this is a wartime national security strategy.” Moving beyond the immediate demands of counterterrorism and missile defense, though, the 2006 strategy sought to address the causes of worldwide instability by “promoting freedom, justice, and human dignity” while also “leading a growing community of democracies.”14
By the middle of the 2000s, however, the post-Soviet “third wave” of democratization was cresting. Increasingly, states that were previously categorized as “democratizing” began backsliding toward a mix of illiberal institutions and fragmented politics.15 The 2008–2009 financial crisis, compounded by a series of bailouts of spendthrift members of the Euro currency zone, exposed economic weaknesses and political divisions among the members of the European Union. In the United States, economic distress compounded existing war-weariness. This mood was reflected in the 2010 NSS, which emphasized that America’s “strength and influence abroad begins with the steps we take at home.”16
During this inwardly focused period, though, rivals of the U.S.-led order began asserting power more openly in their respective regions. Chinese economic growth generated a sense of national confidence that was matched with sustained investment in its military. Developments in antiaccess/area-denial (A2/AD) weapons systems designed to preclude an unimpeded, low-risk American deployment into theater proceeded rapidly. An incremental program of land reclamation and island-building in the South China Sea sought to create the (newly minted) ground that would extend Chinese military and economic power and de facto sovereignty into international waters shared by an array of nations.17 Iran, capitalizing on the power vacuum created by Iraq’s continued instability, involved itself more openly and assertively in Syria, Lebanon, Yemen, and Iraq. Russia flexed its muscles as well by creating and then capitalizing on a series of “frozen conflicts” in regions along its periphery. Some of these manufactured conflicts erupted into open war, such as in 2008 against Georgia and 2014 against Ukraine. Others, namely Transnistria in Moldova and Nagorno-Karabakh in Azerbaijan continue to linger unresolved.18
Viewed in the global power balance, the growth of regional rivals could prompt several possible actions by American allies. Some scholars consider a unipolar system inherently unstable, and that once a credible alternative to the United States rises, states will align with it to balance out overweening American power.19 Others argue that unipolarity is more stable and durable, especially given the shared gains from economic interdependence and the common threat of nonstate actors and rogue states that seek to undermine a rules-based international order that is more democratic, liberal, and prosperous than previous ones. These shared benefits drive states to bandwagon with the American liberal leviathan, rather than counter it.20 Finally, balance-of-threat theory claims that a power’s intent, more than strength, drive in state alliance calculations.21 Given the historical animosities between the rising regional powers and their neighboring American allies, coupled with the pattern of expansion common to Iran, China, and Russia, it follows that leaders in nearby states would see them as a threat and seek to counter them by strengthening their ties with Washington, regardless of the raw balance of global power.
Balance of threat is increasingly supported empirically. In recent years, many American allies have “hard balanced” against their more assertive neighbors by building their military capacities. Persian Gulf states, which have long lavished petrodollars on military hardware, have continued their investments despite lower oil revenues. Saudi Arabia, Kuwait, Qatar, and the United Arab Emirates have all increased their spending on sophisticated American-built antimissile systems to defend against Iran, a trend highlighted by the $110 billion weapons deal struck during President Donald Trump’s 2017 visit to Riyadh.22 Asian states such as Vietnam and Singapore have dramatically increased their spending on naval and air weapons to balance against China. Even Japan, constrained by its pacifist postwar constitution, is investing heavily in expeditionary weapons platforms such as helicopter carriers.23 While Europe has been wracked by economic and political instability, Russia’s invasion of Ukraine inspired action. Sweden, though not a NATO member, has reintroduced conscription and is remilitarizing islands in the Baltic Sea to counter Russian probing.24 Poland is also investing in territorial defenses and now fields the largest tank force in Europe, apart from Russia. NATO members in the Baltics, the likeliest targets of Russian aggression, are developing their forces to counter the subversive gray zone tactics of unmarked soldiers and ethnonationalistic instigation employed earlier against Georgia and the Ukraine.25
While these allied military investments, particularly from NATO members whose forces have atrophied dramatically since the end of the Cold War, are welcomed in Washington, reckless driving—the inverse problem to free riding—can also emerge.26 Reinvigorated American allies facing regional rivals may be overly emboldened by their ties to Washington and rashly launch ambitious military strikes in the belief that the United States will back them up. Georgia’s actions in the summer of 2008, prior to the brief and calamitous war with Russia, were explained in part by overconfidence in its growing ties with NATO.27 Israel’s plans for strikes against Iran’s nuclear sites were widely judged as contingent on American leadership support, which was, in turn, not keen on being drawn hastily into war. The French and British–led air campaign against Muamar Qaddafi’s regime in Libya also hinged on American support, and when the European military efforts stalled, the United States was obliged to take the lead.28
Not all states have pursued hard balancing against the rising threats in their neighborhoods, though. Most NATO countries still fall short of their pledge of spending 2 percent of gross domestic product on defense. The German military, for example, has seen its once-vaunted tank force that numbered over 7,000 in 1991 dwindle to just 237, of which only 100 are combat-ready.29 Given the large economies of many NATO Allies, these levels are less dramatic in absolute terms, but redundant structures, parochial procurement, and competing priorities make NATO less than a sum of its parts.30 Some of America’s more peripheral allies in the Gulf such as Oman and Qatar have hedged their diplomatic alignment with Washington with outreach to Tehran. The Philippines, a longstanding U.S. ally, has pursued engagement with China under President Rodrigo Duterte’s regime. These strategies of accommodation echo the Cold War alignment of Finland and grant legitimacy and momentum to a rising rival.31
In short, a new security dynamic has emerged among the United States, its allies, and their common rivals who seek to upend the American-led, rules-based international order in their respective corners of the world. Accordingly, the debate about the breadth and intensity of American foreign engagement, which paused following September 11, has also reemerged. The 2015 NSS recognized the rising threat of regional powers, most notably from Russia and China, countries that had previously been described largely as partners against terror. The Trump administration’s recently published NSS solidifies this prioritization of revisionist states as the primary threat to American security and prosperity: “China and Russia want to shape a world antithetical to U.S. values and interests.”32 While the challenges to the American-led international order are increasingly clear, the answer is less so, especially with the Trump administration’s frustration with parsimonious allies who look to Washington for continued support. In policy debates, advocates for neo-isolationism or retrenchment, rebranded as “offshore balancing” and billed as a way to reduce free-riding among allies and ease the pressure on an overextend American military, squared off against defenders of continued global engagement.33
The difference between these schools largely hinges on two distinct issues: the expected cost savings from retrenchment and whether nuclear proliferation, even among allies, is tolerable. Supporters of a neo-isolationist policy of offshore balancing or retrenchment often cite the cost savings of a reduced force structure, while their opponents counter that previous withdrawals have ended up costing America more, in both blood and treasure.34 Similarly, advocates of neo-isolationism largely accept a degree of nuclear proliferation among U.S. allies who seek to ensure their security as American power recedes, while those with a more pessimistic view of proliferation argue that extended deterrence is credible only with the continued forward presence of U.S. forces, and therefore continued engagement is critical to containing the spread of nuclear weapons.35
These re-warmed arguments, however, do not capture the fractured threats around the world or consider the significant changes in both American and allied military structure and capabilities. The rival powers that are building their military strength and probing American power and resolve are regional, not global ones. Often their tactics involve quickly manufacturing a small-scale fait accompli, rather than a large-scale invasion through the Fulda Gap or across the Taiwan Strait. Furthermore, there is no universal ideology, such as Soviet communism, that binds America’s rivals together. Similarly, there is no great project, such as building liberal democracy, to focus U.S. allies. Probes by an adversary in one theater are not part of a coordinated, global scheme to test U.S. resolve, as was often the case in the Cold War. This lack of broader cohesion on both sides of the divide results in a fractured array of independent, regional rivalries that are often colored more by historical animosity than by a global struggle between Washington and a single foreign capital.
Caught between the domestic pressure to contain military spending, restraining some rearmed allies from reckless driving while nudging others to bear their fair share of the security burden, and countering a diverse array of regional rivals, a new American approach to building and deploying its military in concert with its allies across the world is in order.
Buttressing America’s network of allies and securing its national interests require acknowledging this new security dynamic and reshaping the military accordingly. While grand strategy can include a broad set of elements, ranging from financial prowess to scientific progress to cultural programs, the rebalancing of America’s global security role presented here centers on military structure and posture. The U.S. military’s outsize importance in American foreign policy is a function of its unmatched size, flexibility, and reach. Changes in structure and posture are expensive, lengthy, and are subject to path-dependent forces and sunk costs. These qualities also make shifts in the American military an unambiguous signal to both allies and adversaries across the world: talk is cheap, but aircraft carriers are expensive.
The unifying logic of this new military strategy is complementary engagement. Complementary engagement hinges on allied investments in their territorial defense, matched with forward-deployed American forces that can be quickly reinforced by globally projected U.S. military power. Forward-deployed U.S. troops would serve three purposes: integrate host-nation defensive forces and American military power, defend infrastructure from A2/AD threats while receiving U.S.-based forces deployed from the homeland during a crisis, and serve as a signal of American commitment. Rather than mirror the structure and capacity of allies, the U.S. military would complement their defenses with its unique capabilities and reach.
While complementary engagement builds on post–Cold War debates among cooperative security, selective engagement, and primacy, it would not have been possible to implement two decades ago. Without reinvigorated allies, some of whom have only recently realized that they must pursue a greater measure of military self-help rather than merely free-ride on the United States for security, a complementary engagement force posture would merely be an overextended version of primacy, shorn of the forward-deployed American combat formations needed to slow an enemy invasion of allied soil. In this sense, complementary engagement builds on, but moves beyond, hybrid strategies proposed in 2012, such as “forward partnership,” as a more cost-effective way for the United States to retain its worldwide footprint than the traditional notion of deep engagement.36 Similarly, without the focused investment in and deployment of high-end strike capabilities and logistics infrastructure detailed later, complementary engagement would essentially be offshore balancing. The unique advantage of complementary engagement, lacking in previous proposals, is the meshing together of American and allied capabilities, a balance that at once dissuades reckless driving and limits free riding.
Complementary engagement hinges on the United States and its partners each bringing critical forces to a conflict, thereby binding their security interests together closely and allowing the political and economic benefits of partnership to flow in both directions. Unlike the deep engagement of the Cold War, where the United States exported security to regions on the Soviet periphery, allowing them to grow economically and develop into liberal democracies, complementary engagement rests on a more equitable set of relationships. While Cold War security engagements were often regional manifestations of the global U.S.-Soviet dichotomy, current tensions are more local and historical, such as Germany-Russia, Saudi Arabia–Iran, and Japan-China. These renewed regional threats have stimulated allied military spending, particularly in East Asia and the Persian Gulf, which complementary engagement uses both for burden-sharing and as a hedge against unilateral action by an ally against a regional adversary.
U.S. military operations are already taking on some characteristics of complementary engagement. The American role in Operation Odyssey Dawn, where intelligence, aerial refueling, and munitions were provided to European air forces flying strike missions over Libya, is a template for complementary engagement. In South Korea, the American footprint is transitioning from frontline warfighter to guarantor for the South’s army, with the unique capabilities and capacity of the U.S. military deterring large-scale aggression by Pyongyang. In the Middle East, the United States provides intelligence, logistics, precision fires, and special operations support to the international coalition fighting the so-called Islamic State (IS). This support allows for the coordinated application of allied assets while enabling regional partners to lead the close fight, a critical element for the ideological defeat of IS.
In summary, complementary engagement is an organizing principle that brings coherence to much of what the military has been doing since the end of the Surge in Iraq. In a sense, it proposes a force that matches both current demands and can better frame allied investments. What is lagging the operational requirements and shifting international context are the force posture and structure of the American military, the concept to which this article turns to next.
Force Structure under Complementary Engagement
This article does not propose any inherently political foreign policy shift by the United States—such a recommendation is beyond the scope of the military. Neither is it a budget-driven scaling of the existing military, with the expected capabilities and reach of a smaller version of Armed Forces driving how ambitious a strategy is possible. Rather, the following proposal outlines a future force structure and posture better suited to fight and win the conflicts that America has recently been engaged in while deterring escalation driven by the more bellicose designs of regional rivals in the context of the existing U.S. alliance structure.
First, the U.S. military must retain and modernize its nuclear forces. Continued extended nuclear deterrence over technologically advanced allies such as Germany, South Korea, and Japan not only protects those states but also dissuades them from developing nuclear weapons themselves in response to a regional threat and possible American neo-isolationism. The sharing of Trident submarine-launched ballistic missile technology with the United Kingdom and the forward-basing of B61 tactical nuclear bombs, deliverable by allied dual-capable fighter aircraft in NATO countries, supports complementary engagement and should be continued.37 While several widely proposed strategic alternatives discount the threat of nuclear proliferation among established allies, complementary engagement is rooted in nuclear pessimism: a greater number of nuclear armed states, even American allies, is inherently destabilizing.
Second, the United States should enhance its long-range strike capabilities. These include the Air Force’s long-range strike bomber (LRSB), long-range standoff (LRSO) cruise missile, ground-based rockets such as the Army Tactical Missile System replacement, and submarine-launched, conventionally armed missile platforms such as the Virginia Payload Module (VPM). Outsize investment by the United States in these systems has several benefits for both America and its allies. First, these weapons can be quickly deployed across the globe, allowing for efficient centralized management of limited, expensive platforms. Second, their ability to strike deep into enemy territory with conventional munitions holds an adversary’s forces at risk, much like Chinese A2/AD capabilities threaten American warships in the western Pacific. Third, these platforms are less threatened by A2/AD systems than aircraft carriers or forward tactical air bases. Finally, and most critically, American control of such weapons reduces the risk of reckless driving by allies, as Washington would have a clear veto over any escalation.
Third, complementary engagement should include air and missile defense. Forward-stationed ballistic missile defenses (BMD) are critical to reassuring allies and enabling the rapid deployment of American reinforcements. Terminal defenses such as the Terminal High-Altitude Air Defense, sea-based Aegis, and shorter range Patriot can reliably protect an ally’s cities, bases, and key infrastructure from ballistic missiles. The success of Israel’s Iron Dome system in countering Hamas rockets during the 2014 war shows how effective missile defense systems can be against conventionally armed rockets. Beyond the benefits of protecting Israeli civilians and property, Iron Dome’s success relieved the political pressure on Israel’s leadership to launch a premature ground offensive into Gaza, pressure that led to mistakes in the 2006 war against Hizballah.38 BMD systems can defend not only allied cities but also the ports where reinforcements would disembark. Terminal defense systems are a reliable way to defend against an enemy’s deadliest weapons while not undermining the balance of nuclear deterrence that exists among the legitimate nuclear powers.
The fourth element of U.S. military force structure to be strengthened under complementary engagement is the backbone of the joint force: expeditionary enablers such as logistics, intelligence, and communications. Air Force tanker, transport, and electronic warfare aircraft; Navy support and auxiliary vessels; and Army logistics distribution, network systems, and prepositioned stocks are the unglamorous connective tissue of America’s military capability. Space platforms that provide secure communications and reconnaissance capabilities are similarly critical. These capabilities can integrate and sustain smaller allied combat elements in an expeditionary campaign, while acting as a brake on overeager reckless driving by an aggrieved ally that is acting beyond America’s interests. They can also enable the rapid deployment of American combat forces based in the continental United States into a crisis theater, allowing for these formations to maintain a high level of readiness and modernization stateside.
A clear example of American use of logistics in support of allied action is the delivery of munitions during a crisis. Many countries rely on the United States for military equipment, and munitions stockpiles are often a lower priority than weapons such as airplanes, tanks, and ships. The emergency delivery of munitions to Israel during the 1973 Yom Kippur War helped turn around the dire situation following the surprise attack by Egypt and Syria. During the 2011 air campaign over Libya, British and French air forces quickly depleted their stocks and were forced to rely on American resupply to sustain the operations against Qaddafi.
In today’s domestic fiscal environment, complementary engagement must be cost neutral. The tradeoffs that allow for increased investment in the four categories listed earlier will affect all Services but will increase the overall efficiency and effectiveness of the military to deter and defeat rising regional rivals. U.S. military force structure changes traditionally focuses on tradeoffs among key force elements such as Navy aircraft carrier strike groups (CSGs), Air Force tactical air wings, Marine divisions, or Army brigade combat teams. Many recent studies of possible future forces structure revolve around these same key force elements and recommend scaled versions of today’s military, which in turn reflects the Cold War structure that formed the basis for the drawdown debates of the 1990s.39 While there are marginal changes to special operations and cyberwarfare capabilities, the mix of key force elements that drive the lion’s share of American military structure are taken for granted.
With complementary engagement’s additional emphasis on nuclear recapitalization, ballistic missile defense, and theater enablers, some of the traditional key force elements will face downward budgetary pressures. Emerging capabilities such as the LRSB, LRSO, and VPM duplicate the strike capabilities of the CSG at lower cost and higher survivability, reducing the requirement for carriers and freeing their escorts to fight as independent squadrons of surface combatants. The capabilities of smaller, less capable vessels such as the littoral combat ship (LCS) are easily duplicated by our allies, who routinely deploy similarly sized corvettes with greater combat power and reliability than the LCS. Increased A2/AD threats make large-scale airborne or amphibious operations unacceptably risky, and the units tailored for these missions should be reduced in a future force structure to numbers capable of large-scale raids, rather than attempted invasions. Both the Army and Marine Corps would retain much of their current combat strength but would increasingly focus on interoperability with allies through rotational force deployments and exercises. Active component theater enablers, forward deployed and continuously used, would replace some Reserve component units. Air Force tactical fighter aircraft—platforms common among American allies—would decrease in number but increase in effectiveness through improved tankers, networked sensors, and allied interoperability.
Complementary engagement does carry some risks. First, it assumes sustained military spending by allies, a continuation of the current trend. American allies, particularly in Europe, are being pressured to increase defense spending by both Washington and a newly assertive Russia, and complementary engagement gives them a framework to prioritize this spending. A larger concern is that the states closest to the rising regional rivals—countries whose military expenditures are generally growing—will opt to equip their forces with a full range of offensive and technically ambitious weapons systems, much like France did with its independent nuclear force de frappe under Charles de Gaulle in the 1960s. This risks duplicating American capabilities at high costs, limiting more sensible investments in territorial defense, while also enabling reckless driving in a crisis. Complementary engagement mitigates this risk by giving America’s allies a clear plan of military investment that maximizes their national defense.
Second, although it retains the capacity for unilateral American action, complementary engagement reduces the quantity of forces available for such action. Sustained, large-scale, out-of-area missions, even with a coalition of American allies, would be less viable as these forces focus on territorial defense. While this trend away from large contributions to nation-building missions is already under way, complementary engagement will exacerbate it. While there is a risk that an emerging crisis will call for such a deployment, policy guidance since 2012 has already assumed this risk: as the 2012 Defense Strategic Guidance states, “U.S. forces will no longer be sized to conduct large-scale, prolonged stability operations.”40
Geopolitically, a shift toward complementary engagement may be interpreted as retrenchment without sustained, and public, rotations of American combat units to forward bases in concert with allied forces. Clear, visible, on-the-ground demonstrations of continued American presence, will, and capability are critical to ensuring that neither America’s adversaries nor wavering allies perceive the United States as attempting to balance from a distance. While such exercises will be conducted by the U.S. military, nesting them with the Department of State’s public diplomacy capabilities multiplies their effect. U.S. Army Europe’s synchronization of Operation Dragoon Ride with a range of NATO Allies and with the U.S. State Department is an illustrative example of this approach.41
Complementary engagement builds on the grand strategic options first laid out in the 1990s. Rather than merely updating the arguments from two decades ago, complementary engagement integrates the current strategic context of emerging regional powers, reinvigorated allies, ballistic missile threats, and nuclear proliferation to propose a new military structure and posture. By rebalancing relationships with allies and partners across the globe for more equitable military burden-sharing while investing heavily in ballistic missile defense, long-range strike, logistics, communications, and nuclear weapons capabilities, the United States can continue to underwrite a rules-based international system that creates the conditions for economic growth, liberal democracy, and regional stability. Importantly, complementary engagement lays the groundwork not only to enable allied defense but also to restrain any reckless driving that could pull the United States into an unnecessary war with a rising rival on behalf of an overeager ally.
The resulting military force structure would build the aforementioned capabilities while reducing other key force elements, all while retaining the capacity to fight and win a unilateral war. While there are some risks to this grand strategy of complementary engagement, the benefits of closely binding our allies and partners to our military make it the best way to further a more peaceful, prosperous, and free world. JFQ
1 John G. Ikenberry, Liberal Leviathan: The Origins, Crisis, and Transformation of the American World Order (Princeton: Princeton University Press, 2011).
2 Summary of the 2018 National Defense Strategy (Washington, DC: Department of Defense, 2018).
3 Jakub J. Grygiel and Mitchell A. Wess, The Unquiet Frontier: Rising Rivals, Vulnerable Allies, and the Crisis of American Power (Princeton: Princeton University Press, 2016).
4 Barry Posen, Restraint: A New Foundation for U.S. Grand Strategy (Ithaca, NY: Cornell University Press, 2014). In addition to Posen, see Joseph Collins, “Toward a Future National Strategy: A Review Essay,” Joint Force Quarterly 84 (1st Quarter 2017), 93–98; and Eliot A. Cohen, The Big Stick: The Limits of Soft Power and the Necessity of Military Force (Boulder, CO: Basic Books, 2017).
5 Joseph S. Nye, “The Case for Deep Engagement,” Foreign Affairs 74, no. 4 (1995), 90–102.
6 John Mearsheimer, “America Unhinged,” The National Interest, no. 129 (January 2014).
7 Barry R. Posen and Andrew L. Ross, “Competing Visions for U.S. Grand Strategy,” International Security 21, no. 3 (1996), 5–53.
8 John G. Ikenberry, Michael Mastanduno, and William C. Wohlforth, “Unipolarity, State Behavior, and Systemic Consequences,” World Politics 61, no. 1 (January 2009), 1–27.
9 Robert J. Art, “Geopolitics Updated: The Strategy of Selective Engagement,” International Security 23, no. 3 (1998), 80–113.
10 Posen and Ross, “Competing Visions for U.S. Grand Strategy.”
11 Posen, Restraint.
12 A National Security Strategy for a New Century (Washington, DC: The White House, 1998).
13 The National Security Strategy of the United States of America (Washington, DC: The White House, 2002).
14 The National Security Strategy of the United States of America (Washington, DC: The White House, 2006).
15 Steven Levitsky and Lucan Way, Competitive Authoritarianism: Hybrid Regimes after the Cold War (New York: Cambridge University Press, 2010).
16 National Security Strategy (Washington, DC: The White House, 2010).
17 Evan Braden Montgomery, “Contested Primacy in the Western Pacific: China’s Rise and the Future of U.S. Power Projection,” International Security 38, no. 4 (April 2014), 115–149.
18 Theodor Tudoroiu, “The European Union, Russia, and the Future of the Transnistrian Frozen Conflict,” East European Politics & Societies 26, no. 1 (February 2012), 135–161.
19 John J. Mearsheimer, The Tragedy of Great Power Politics (New York: Norton, 2001).
20 William Wohlforth, “The Stability of a Unipolar World,” International Security 24, no. 1 (1999), 5–41; and Stephen M. Walt, “Alliances in a Unipolar World,” World Politics 61, no. 1 (January 2009), 86–120.
21 Stephen M. Walt, The Origins of Alliances (Ithaca, NY: Cornell University Press, 1987).
22 Helene Cooper, “Senate Narrowly Backs Trump Weapons Sale to Saudi Arabia,” New York Times, June 13, 2017.
23 Grygiel and Mitchell, The Unquiet Frontier.
24 Martin Sorensen, “Sweden Reinstates Conscription, with an Eye on Russia,” New York Times, March 2, 2017.
25 Janis Berzins, Russia’s New Generation Warfare in Ukraine: Implications for Latvian Defense Policy, Policy Paper No. 2 (Riga, Latvia: National Defense Academy of Latvia, Center for Security and Strategic Research, 2014).
26 Barry R. Posen, “Pull Back: The Case of a Less Activist Foreign Policy,” Foreign Affairs 92, no. 1 (2013), 116–128.
27 Vicken Cheterian, “The August 2008 War in Georgia: From Ethnic Conflict to Border Wars,” Central Asian Survey 28, no. 2 (June 2009), 155–170.
28 Christian F. Anrig, “Allied Air Power over Libya: A Preliminary Assessment,” Air & Space Power Journal 25, no. 4 (2011), 89–110.
29 Anthony Cordesman, NATO and the Delicate Balance of Deterrence: Strategy versus Burden Sharing (Washington, DC: Center for Strategic and International Studies, 2017).
30 Scott Boston et al., Assessing the Conventional Force Imbalance in Europe: Implications for Countering Russian Local Superiority (Washington, DC: RAND, 2018).
31 Grygiel and Mitchell, The Unquiet Frontier.
32 National Security Strategy (Washington, DC: The White House, 2017).
33 John Mearsheimer and Stephen M. Walt, “The Case for Offshore Balancing: A Superior U.S. Grand Strategy,” Foreign Affairs, July/August 2016.
34 Henry R. Nau, Conservative Internationalism: Armed Diplomacy under Jefferson, Polk, Truman, and Reagan (Princeton: Princeton University Press, 2015).
35 Stephen G. Brooks and William Wohlforth, America Abroad: The United States’ Global Role in the 21st Century (New York: Oxford, 2016).
36 F.G. Hoffman, “Forward Partnership: A Sustainable American Strategy,” Orbis 57, no. 1 (December 2013), 20–40.
37 Nuclear Posture Review (Washington, DC: Office of the Secretary of Defense, 2018).
38 Emily B. Landau and Azriel Bermant, “Iron Dome Protection: Missile Defense in Israel’s Security Concept,” in The Lessons of Operation Protective Edge, ed. Anat Kurz and Schlomo Brom (Tel Aviv: Institute of National Security Studies, 2015), 37–42.
39 John McCain, Restoring American Power: Recommendations for the FY 2018–FY 2022 Defense Budget (Washington, DC: Senate Armed Services Committee, 2017).
40 Sustaining U.S. Global Leadership: Priorities for 21st-Century Defense (Washington, DC: The White House, 2012).
41 John Vandiver, “Dragoon Ride Will Send U.S. Troops Through Eastern Europe in Show of Support,” Stars and Stripes, March 12, 2015.