The United States maintains a military force primarily to protect the homeland from attack and to protect its interests abroad. There are secondary uses—for example, to assist civil authorities in times of emergency or to deter enemies—but this force’s primary purpose is to make possible the physical imposition of will on an enemy when necessary.

Understanding the condition of the United States military with respect to America’s vital national security interests, any threats to those interests, and the context within which the U.S. might have to use “hard power” is therefore of critical importance. Knowing how these three areas—operating environments, threats, and the posture of the U.S. military—change over time, given that such changes can have substantial implications for defense policies and investment, is likewise important.

Each year, The Heritage Foundation’s Index of U.S. Military Strength employs a standardized, consistent set of criteria, accessible both to government officials and to the American public, to gauge the U.S. military’s ability to perform its missions in today’s world. The inaugural 2015 edition established a baseline assessment on which each annual edition builds, assessing the state of affairs for its respective year and measuring how key factors have changed from the previous year.

What the Index Assesses

The Index of U.S. Military Strength assesses the ease or difficulty of operating in key regions based on existing alliances, regional political stability, the presence of U.S. military forces, and the condition of key infrastructure. Threats are assessed based on the behavior and physical capabilities of actors that pose challenges to U.S. vital national interests. The condition of America’s military power is measured in terms of its capability or modernity, capacity for operations, and readiness to handle assigned missions successfully. This framework provides a single-source reference for policymakers and other Americans who seek to know whether our military power is up to the task of defending our national interests.

Any discussion of the aggregate capacity and breadth of the military power needed to protect U.S. security interests requires a clear understanding of precisely what interests must be defended. Over the past few decades, three vital interests have been specified consistently and in various ways by a string of Administrations:

Defense of the homeland;

of the homeland; Successful conclusion of a major war that has the potential to destabilize a region of critical interest to the United States; and

of a major war that has the potential to destabilize a region of critical interest to the United States; and Preservation of freedom of movement within the global commons (the sea, air, outer-space, and cyberspace domains) through which the world conducts its business.

To defend these interests effectively on a global scale, the United States needs a military force of sufficient size, or what is known in the Pentagon as capacity. The many factors involved make determining how big the military should be a complex exercise, but successive Administrations, Congresses, and Department of Defense (DOD) staffs have managed to arrive at a surprisingly consistent force-sizing rationale: an ability to handle two major wars or major regional contingencies (MRCs) simultaneously or in closely overlapping time frames.

At its root, the current National Defense Strategy (NDS) implies the same force requirement. Its emphasis on a return to long-term competition with major powers, explicitly naming Russia and China as primary competitors,1 reemphasizes the need for the United States to have:

Sufficient military capacity to deter or win against large conventional powers in geographically distant regions;

The ability to conduct sustained operations against lesser threats; and

The ability to work with allies and maintain a U.S. presence in regions of key importance that is sufficient to deter behavior that threatens U.S. interests.

No matter how much America desires the world to be a simpler, less threatening place, more inclined to beneficial economic interactions than it is to violence-laden friction, the patterns of history show that competing powers consistently emerge and that the U.S. must be able to defend its interests in more than one region at a time. Consequently, this Index embraces the two-war or two-MRC requirement.

Since World War II, the U.S. has found itself involved in a major “hot” war every 15–20 years while simultaneously maintaining substantial combat forces in Europe and several other regions. The size of the total force has roughly approximated the two-MRC model, which has the inherent ability to meet multiple security obligations to which the U.S. has committed while also modernizing, training, educating, and maintaining the force. Accordingly, our assessment of the adequacy of today’s U.S. military is based on the ability of America’s armed forces to engage and defeat two major competitors at roughly the same time.

We acknowledge that unless a dramatic change in circumstances occurs, such as the onset of a major conflict, a multitude of competing interests that evolve during extended periods of peace and prosperity will lead Administrations and Congresses to deemphasize investing in defense and instead to favor domestic programs. Consequently, garnering sufficient support to increase defense spending for a two-war-capacity force is problematic. However, this political condition does not change the patterns of history, the behavior of competitors, or the reality of what it takes to defend America’s interests in an actual war.

This Index’s benchmark for a two-MRC force is derived from a review of the forces used for each major war that the U.S. has undertaken since World War II and the major defense studies completed by the federal government over the past 30 years. We concluded that a standing (Active Duty component) two-MRC–capable Joint Force would consist of:

Army: 50 brigade combat teams (BCTs);

50 brigade combat teams (BCTs); Navy: 400 battle force ships and 624 strike aircraft;

400 battle force ships and 624 strike aircraft; Air Force: 1,200 fighter/ground-attack aircraft; and

1,200 fighter/ground-attack aircraft; and Marine Corps: 36 battalions.

This recommended force does not account for homeland defense missions that would accompany a period of major conflict and are generally handled by Reserve and National Guard forces. Nor does it constitute the totality of the Joint Force, which includes the array of supporting and combat-enabling functions essential to the conduct of any military operation: logistics; transportation (land, sea, and air); health services; communications and data handling; and force generation (recruiting, training, and education), to name only a few. Rather, these are combat forces that are the most recognizable elements of America’s hard power but that also can be viewed as surrogate measures for the size and capability of the larger Joint Force.

The Global Operating Environment

Looking at the world as an environment in which U.S. forces would operate to protect America’s interests, the Index focused on three regions—Europe, the Middle East, and Asia—because of the intersection of our vital interests and actors able to challenge them.

Europe. Overall, the European region remains a stable, mature, and friendly operating environment. Russia remains the preeminent military threat to the region, both conventionally and unconventionally. America’s closest and oldest allies are located in Europe, and the region is incredibly important to the U.S. for economic, military, and political reasons.

Perhaps most important, the U.S. has treaty obligations through NATO to defend the European members of that alliance. If the U.S. needs to act in the European region or nearby, there is a history of interoperability with allies and access to key logistical infrastructure that makes the operating environment in Europe more favorable than the environment in other regions in which U.S. forces might have to operate.

The past year saw continued U.S. reengagement with the continent, both militarily and politically, along with modest increases in European allies’ defense budgets and capability investment. Despite allies’ initial concerns, the U.S. has increased its investment in Europe, and its military position on the continent is the strongest it has been for some time.

NATO’s renewed focus on collective defense has resulted in a focus on logistics, newly established commands that reflect a changed geopolitical reality, and a robust set of exercises. NATO’s biggest challenges derive from capability and readiness gaps for many European nations, continuing improvements and exercises in the realm of logistics, a tempestuous Turkey, disparate threat perceptions within the alliance, and the need to establish the ability to mount a robust response to both linear and nonlinear forms of aggression.

For Europe, scores this year remained steady, as they did in 2018 (assessed in the 2019 Index), with no substantial changes in any individual categories or average scores. The 2020 Index again assesses the European Operating Environment as “favorable.”

The Middle East. For the foreseeable future, the Middle East region will remain a key focus for U.S. military planners because of the immediacy of its security challenges, even though the National Defense Strategy has called upon the DOD to reorient toward major-power competition with China and Russia. Once considered relatively stable, mainly because of the ironfisted rule of authoritarian regimes, the area is now highly unstable and a breeding ground for terrorism.

Overall, regional security has deteriorated in recent years. The Islamic State appears to have been defeated in a conventional sense, but the nature of its successor is unclear. In Iraq, future relations between Baghdad and the U.S. will remain difficult as long as a government that is sympathetic to Iran is in power. The regional dispute with Qatar has made U.S. relations in the region even more complex and difficult to manage.

In countries like Iraq, Libya, Syria, and Yemen, the supremacy of the nation-state is challenged by a multitude of non-state actors. The region’s principal security and political challenges are linked to the unrealized aspirations of the Arab Spring, surging transnational terrorism, and meddling by Iran, which seeks to extend its influence in the Islamic world. All of this is made more difficult by the Arab–Israeli conflict, Sunni–Shia sectarian divides, the rise of Iran’s Islamist revolutionary nationalism, and the proliferation of Sunni Islamist revolutionary groups.

America’s relationships in the region are based pragmatically on shared security and economic concerns. As long as these issues remain relevant to both sides, the U.S. is likely to have an open door to operate in the Middle East when its national interests require that it do so.

Though circumstances in all measured areas vary throughout the year, in general terms, the 2020 Index assesses the Middle East Operating Environment as “moderate,” although the region’s political stability continues to be “unfavorable.”

Asia. The Asian strategic environment is extremely expansive, as it includes half the globe and is characterized by a variety of political relationships among states that have wildly varying capabilities. The region includes long-standing American allies with relationships dating back to the beginning of the Cold War as well as recently established states and some long-standing adversaries such as North Korea.

American conceptions of the region must therefore recognize the physical limitations imposed by the tyranny of distance. Moving forces within the region (never mind to it) will take time and require extensive strategic lift assets as well as sufficient infrastructure, such as sea and aerial ports of debarkation that can handle American strategic lift assets, and political support. At the same time, the complicated nature of intra-Asian relations, especially unresolved historical and territorial issues of the type most recently exhibited in renewed tension between South Korea and Japan, means that the United States, unlike Europe, cannot necessarily count on support from all of its regional allies in responding to any given contingency.

For Asia, we continue to assess it as “favorable” to U.S. interests in terms of alliances, overall political stability, militarily relevant infrastructure, and the presence of U.S. military forces.

Summarizing the condition of each region enables us to get a sense of how they compare in terms of the challenges the U.S. would face in projecting military power and sustaining combat operations in each one. As a whole, the global operating environment currently maintains a score of “favorable,” which means that the United States should be able to project military power anywhere in the world as necessary to defend its interests without substantial opposition or high levels of risk.

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Threats to U.S. Interests

Our selection of threat actors discounted troublesome states and non-state entities that lack the physical ability to pose a meaningful threat to vital U.S. security interests. This reduced the population of all potential threats to a half-dozen that possess the means to threaten U.S. vital interests and exhibit a pattern of provocative behavior that should draw the focus of U.S. defense planning. This Index characterizes their behavior and military capabilities on five-point, descending scales.

All of the six threat actors selected—Russia, China, Iran, North Korea, and terrorist groups in the Middle East and Afghanistan—remained actual or potential threats to U.S. interests over the past year. All amply demonstrated a commitment to expanding their capabilities to pursue their respective interests that directly challenged those of the U.S.

Compiling the assessments of threat sources, the 2020 Index again rates the overall global threat environment as “aggressive” and “gathering” in the areas of threat-actor behavior and material ability to harm U.S. security interests, respectively, leading to an aggregated threat score of “high.”

Just as there are American interests that are not covered by this Index, there may be additional threats to American interests that are not identified here. The Index focuses on the more apparent sources of risk and those that appear to pose the greatest threat.

Russia remains the primary threat to American interests in Europe and is the most pressing threat to the United States. Moscow continues to engage in massive pro-Russia propaganda campaigns in Ukraine and other Eastern European countries, actively supports separatist forces in Ukraine, regularly performs provocative military exercises and training missions, and continues to sell and export arms to countries that are hostile to U.S. interests. It also has increased its investment in modernizing its military and has gained significant combat experience while continuing to sabotage U.S. and Western policy in Syria and Ukraine.

The 2020 Index again assesses the threat emanating from Russia as “aggressive” in its behavior and “formidable” (the highest category on the scale) in its growing capabilities.

China, the most comprehensive threat the U.S. faces, remained “aggressive” in the scope of its provocative behavior and earns the score of “formidable” for its capability because of its ongoing military modernization and buildup. The People’s Liberation Army continues to extend its reach and military activity beyond its immediate region and engages in larger and more comprehensive exercises, including live-fire exercises in the East China Sea near Taiwan. It also has continued to conduct probes of the South Korean and Japanese air defense identification zones, drawing rebukes from both Seoul and Tokyo. In addition, there is little evidence that Chinese cyber espionage and computer network exploitation have abated.

Iran remains the state actor that is most hostile to American interests in the Middle East. The 2020 Index assesses Iran’s behavior as “aggressive” and its capability as “gathering.”

In the years since publication of the 2015 Index, Iran has methodically moved closer to becoming a nuclear power, and it continues to enhance its ICBM, missile defense, and unmanned systems capabilities. Iran also continues to perpetuate and exploit instability to expand its influence in the region, both in its direct involvement in regional engagements and through its proxies, particularly in Syria. This year also saw aggressive activity in the Strait of Hormuz, including the downing of a U.S. drone in international airspace and attacks on merchant shipping.

North Korea’s level of behavior remained “testing” in the 2020 Index. North Korea’s capability level has also remained at “gathering” as Pyongyang continues to develop and refine its missile technology, especially in the area of submarine-launched ballistic missiles. With its ICBM program, North Korea remains both a threat to U.S. allies and assets in the region and an ongoing threat to the U.S. homeland.

The terrorist threats emanating from the Afghanistan–Pakistan region remained “testing” in the 2020 Index. Fatalities attributed to terrorism inside Pakistan continue to fall as various terrorist groups within the region find themselves in competition with each other for recruits, territory, and resources.

A broad array of terrorist groups remain the most hostile of any of the threats to America examined in the Index. As of mid-2018, the Islamic State had been decimated, having lost more than 98 percent of its previously held territory, and its further reduction continued in 2019. However, it has not been completely eliminated and has made efforts to reassert itself in the region. Fortunately, Middle East terrorist groups are the least capable of the threats facing the U.S.

Our combined score for threats to U.S. vital interests is “high,” the fourth on a five-level scale, just below “severe.”

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The Status of U.S. Military Power

Finally, we assessed the military power of the United States in three areas: capability, capacity, and readiness. We approached this assessment by military service as the clearest way to link military force size; modernization programs; unit readiness; and (in general terms) the functional combat power (land, sea, and air) represented by each service. We treated the United States’ nuclear capability as a separate entity because of its truly unique characteristics and constituent elements, from the weapons themselves to the supporting infrastructure that is fundamentally different from the infrastructure that supports conventional capabilities.

These three areas of assessment (capability, capacity, and readiness) are central to the overarching questions of whether the U.S. has a sufficient quantity of appropriately modern military power and whether military units are able to conduct military operations on demand and effectively.

As reported in all previous editions of the Index, the common theme across the services and the U.S. nuclear enterprise is one of force degradation caused by many years of underinvestment, poor execution of modernization programs, and the negative effects of budget sequestration (cuts in funding) on readiness and capacity in spite of repeated efforts by Congress to provide relief from low budget ceilings imposed by the Budget Control Act of 2011 (BCA) through two-year budget agreements that either waived the BCA caps or provided extra funding in contingency accounts not subject to BCA limits. Subsequent to new guidance provided by then-Secretary of Defense James Mattis in the 2018 NDS, the services undertook efforts to reorient from irregular warfare to large-scale combat against a peer adversary, but such shifts take time and even more resources.

While the military has been heavily engaged in operations, primarily in the Middle East but elsewhere as well, since September 11, 2001, experience in warfare is both ephemeral and context-sensitive. Valuable combat experience is lost as the servicemembers who individually gained experience leave the force, and it maintains direct relevance only for future operations of a similar type: Counterinsurgency operations in Iraq, for example, are fundamentally different from major conventional operations against a state like Iran or China.

In general, the withdrawal of U.S. military forces from Iraq in 2011 and the steady reduction of forces in Afghanistan have amplified the loss of direct combat experience across the Joint Force. Thus, although portions of the current Joint Force are experienced in some types of operations, the force as a whole lacks experience with high-end, major combat operations toward which it has only begun to redirect its training and planning. It is also still aged and shrinking in its capacity for operations even though limited quantities of new equipment like the F-35 Lightening II fighter are gradually being introduced.

We characterized the services and the nuclear enterprise on a five-category scale ranging from “very weak” to “very strong,” benchmarked against criteria elaborated in the full report. These characterizations should not be construed as reflecting the competence of individual servicemembers or the professionalism of the services or Joint Force as a whole; nor do they speak to the U.S. military’s strength relative to the strength of other militaries around the world. Rather, they are assessments of the institutional, programmatic, and material health or viability of America’s hard military power.

Our analysis concluded with these assessments:

Army as “Marginal.” The Army’s score remains “marginal” in the 2020 Index. The Army has continued to increase its readiness, earning the score of “very strong” with 77 percent of its BCTs assessed as ready. However, it continues to struggle to rebuild end strength (attempting to grow from nearly 480,000 to 500,000) and to modernize the force for improved readiness in some units for current operations.

The Army’s score remains “marginal” in the The Army has continued to increase its readiness, earning the score of “very strong” with 77 percent of its BCTs assessed as ready. However, it continues to struggle to rebuild end strength (attempting to grow from nearly 480,000 to 500,000) and to modernize the force for improved readiness in some units for current operations. Navy as “Marginal.” The Navy’s overall score remains “marginal” in the 2020 Index . The Navy’s emphasis on restoring readiness and increasing its capacity signals that its overall score could improve in the near future if needed levels of funding are sustained. However, manpower presents a potential problem as does obtaining adequate funding to increase the number of ships in the fleet more rapidly. Shortfalls in funding and a general shortage of available shipyards have led to a substantial backlog in ship maintenance, placing an additional burden on those ships and crews that are available for deployment.

The Navy’s overall score remains “marginal” in the . The Navy’s emphasis on restoring readiness and increasing its capacity signals that its overall score could improve in the near future if needed levels of funding are sustained. However, manpower presents a potential problem as does obtaining adequate funding to increase the number of ships in the fleet more rapidly. Shortfalls in funding and a general shortage of available shipyards have led to a substantial backlog in ship maintenance, placing an additional burden on those ships and crews that are available for deployment. Air Force as “Marginal.” This score has trended downward over the past few years largely because of a drop in capacity that has not effectively changed (sitting at just under 80 percent of needed fighter/attack aircraft, for example) and a readiness score of “marginal,” better than its score of “weak” in the 2019 Index but still not where it needs to be. Shortages of pilots and flying time have degraded the ability of the Air Force to generate the air power that would be needed to meet wartime requirements.

This score has trended downward over the past few years largely because of a drop in capacity that has not effectively changed (sitting at just under 80 percent of needed fighter/attack aircraft, for example) and a readiness score of “marginal,” better than its score of “weak” in the but still not where it needs to be. Shortages of pilots and flying time have degraded the ability of the Air Force to generate the air power that would be needed to meet wartime requirements. Marine Corps as “Marginal.” The Corps has prioritized regaining combat readiness across the force, elevating it above expanding the size of the service. Aviation remained one of the largest challenges for the Corps in 2019, driven by sustainment challenges within its legacy fleet of aircraft and shortfalls in key maintenance support personnel. The increase in readiness among ground units and some advances in introducing new platforms, such as completion of MV-22 fielding in the active component, somewhat offset shortfalls in capacity and a “ready bench” to return the Marine Corps to an overall strength score of “marginal.”

The Corps has prioritized regaining combat readiness across the force, elevating it above expanding the size of the service. Aviation remained one of the largest challenges for the Corps in 2019, driven by sustainment challenges within its legacy fleet of aircraft and shortfalls in key maintenance support personnel. The increase in readiness among ground units and some advances in introducing new platforms, such as completion of MV-22 fielding in the active component, somewhat offset shortfalls in capacity and a “ready bench” to return the Marine Corps to an overall strength score of “marginal.” Nuclear Capability as “Marginal.” The U.S. is not taking full advantage of current technologies to field modern warheads that could be designed to be safer and more secure with increased effectiveness and could give the United States better options for strengthening a credible deterrent. Instead, the U.S. has elected largely to maintain aging nuclear warheads that were in the stockpile when the Cold War ended nearly 30 years ago. In addition to warheads, the U.S. nuclear enterprise has many other components, some of which also support conventional military and extended deterrence missions. Thus, assessing whether any one piece of the enterprise is sufficiently funded, focused, and effective is difficult. That said, this Index assesses the nuclear complex as “marginal, trending toward strong,” but this assumes that the U.S. maintains its commitment to modernization and allocates needed resources accordingly. Although bipartisan attention has led to continued progress on U.S. nuclear forces modernization and warhead sustainment, these programs remain threatened by potential future fiscal uncertainties, as are the infrastructure, testing regime, and manpower pool on which the nuclear enterprise depends.

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In the aggregate, the United States’ military posture is rated “marginal” and features both positive and negative trends: progress in bringing some new equipment into the force, filling gaps in manpower, and rebuilding some stocks of munitions and repair parts alongside worrisome trends in force readiness, declining strength in key areas like trained pilots, and continued uncertainty across the defense budget.

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The 2020 Index concludes that the current U.S. military force is likely capable of meeting the demands of a single major regional conflict while also attending to various presence and engagement activities but that it would be very hard-pressed to do more and certainly would be ill-equipped to handle two nearly simultaneous major regional contingencies. The military services have prioritized readiness and seen improvement over the past couple of years, but modernization programs continue to suffer as resources are redirected toward current operations and sustainment of readiness levels. The services have also normalized the reduction in size and number of military units, and the forces remain well below the level needed to meet the two-MRC benchmark.

Congress and the Administration took positive steps to stabilize funding for FY 2018 and FY 2019 through the Bipartisan Budget Agreement of 2018 and managed, through the Bipartisan Budget Act of 2019, to sustain such support for funding above the caps imposed by the Budget Control Act of 2011 (BCA). While this allays the most serious concerns about a possible return to the damaging levels of the BCA, more will be needed in the years to come to ensure that the U.S. military is properly sized, equipped, trained, and ready to meet the missions that the services are called upon to fulfill.

As currently postured, the U.S. military is only marginally able to meet the demands of defending America’s vital national interests.

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