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 disaster or to deter opponents from threatening America’s interests—but this force’s primary purpose is to make it possible for the U.S. to physically impose its will on an enemy when necessary.

Consequently, it is critical that the condition of the United States military with respect to America’s vital national security interests, threats to those interests, and the context within which the U.S. might have to use “hard power” be understood. 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 ability of the U.S. military to perform its missions in today’s world. The inaugural 2015 edition established a baseline assessment on which this and future annual editions will build, with each edition 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 address threats to U.S. security interests requires a clear understanding of precisely what interests must be defended. Three vital interests have been stated consistently in various ways by a string of Administrations over the past few decades:

  • Defense of the homeland;
  • Successful conclusion of a major war that has the potential to destabilize a region of critical interest to the U.S.; 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.” Due to the many factors involved, determining how big the military should be is a complex exercise. However, successive Administrations, Congresses, and Department of Defense 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. This “two-war” or “two-MRC” requirement is embraced in this Index.

At the core of this requirement is the conviction that the United States should have the ability to engage and decisively defeat one major opponent and simultaneously have the wherewithal to do the same with another to preclude opportunistic exploitation by any competitor. 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 roughly approximated the two-MRC model. 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.

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 (i.e., Active Duty component) two-MRC–capable Joint Force would consist of:

  • Army: 50 brigade combat teams (BCTs);
  • Navy: 346 surface combatants and 624 strike aircraft;
  • Air Force: 1,200 fighter/ground-attack aircraft; and
  • Marine Corps: 36 battalions.

This 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 this recommended force 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 a very 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. For the most part, Europe is a stable, mature, and friendly environment, home to America’s oldest and closest allies. The U.S. is tied to it by treaty, robust economic bonds, and deeply rooted cultural linkages. In general, America’s partners in the region are politically stable; possess mature (if increasingly debt-laden) economies; and have fairly modern (though shrinking) militaries. America’s longtime presence in the region, Europe’s well-established basing and support infrastructure, and the framework for coordinated action provided by NATO make the region quite favorable for military operations.

The Middle East. In contrast, the Middle East is a deeply troubled area that continues to be riven with conflict, ruled by authoritarian regimes, and populated by an increasing number of terrorist and other destabilizing entities. Though the United States does enjoy a few strong partnerships in the region, its interests are beset by security and political challenges, expanding transnational terrorism, and the maturing threat of a nuclear Iran. Offsetting these challenges to some extent are the U.S. military’s experience in the region and the basing infrastructure that it has developed and leveraged for nearly 25 years, although these positive elements are decaying as a consequence of America’s withdrawal from Iraq, its reduced presence in neighboring countries, and the increasingly problematic political environment in countries that historically have hosted U.S. forces.

Asia. Asia’s defining characteristic is its expanse, covering 30 percent of the globe’s land area. Though the region includes long-standing allies of the U.S. that are stable and possess advanced economies, the tyranny of distance makes U.S. military operations in the region difficult in terms of the time and sealift and airlift that are required, a challenge that is only exacerbated as the size of the U.S. military continues to shrink.

Summarizing the condition of each region enables us to get a sense of how they compare in terms of the challenge the U.S. would have in projecting military power and sustaining combat operations in each one.

As a whole, the global operating environment currently rates a score of “favorable,” meaning 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, although conditions in the Middle East (and perhaps Europe) could easily tip this aggregate score into the “moderate” category if conditions continue to degrade in 2017.

Threats to U.S. Interests

Our selection of threat actors discounted troublesome states and non-state entities that lacked the physical ability to pose a meaningful threat to the vital security interests of the U.S. This reduced the population of all potential threats to a half-dozen that possessed both the means to threaten U.S. vital interests and 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.

Each of the six threat actors continued to be particularly aggressive during 2016, with a not altogether surprising correlation of physical capability and state robustness or coherence. Our scoring resulted in the individual marks depicted below.

Combining the assessments of behavior and capability led to a general characterization of each threat, ranging from “severe” to “low.” Worryingly, all six noted threat actors now rank “high” on the scale of threats to U.S. interests, although the threat from North Korea dropped one category from “severe” to “high.”

While all six threats have been quite problematic in their behavior and in their impact on their respective regions, Russia and China continue to be the most worrisome, both because of the investments they are making in the modernization and expansion of their offensive military capabilities and because of the more enduring effect they are having within their respective regions. Russia has maintained its active involvement in the conflict in Ukraine and has inserted itself into the Syrian conflict, and China’s provocative behavior has expanded to include militarization of islands that it has built in highly disputed international waters in the South China Sea. China has also adopted aggressive naval tactics to intimidate such neighboring countries as Japan and the Philippines.

North Korea warrants sustained attention. It has reportedly developed a nuclear-capable ballistic missile with sufficient range to reach the United States and continues to invest heavily in developing a submarine-launched ballistic missile, an effort that has generated heightened concerns among U.S. allies in the region.

Terrorism based in Afghanistan and Pakistan continues to hold a strong potential to spark a large-scale conflict between Pakistan and India (two nuclear powers) or even to pose a nuclear threat to others should radicalized Islamists gain control of Pakistan’s nuclear arsenal or destabilize Pakistan’s government, which would result in the loss of positive control of Pakistan’s inventory of nuclear weapons.

In addition, Iran and the various terrorist groups operating in the Middle East would be a greater threat to U.S. security interests than they currently are if they possessed a greater physical ability to project military power outside of their immediate areas. Such a concern was amplified during 2016 when the U.S. Administration finalized an international agreement pertaining to Iran’s nuclear aspirations that effectively enables Iran to maintain its nuclear research and development infrastructure and associated ballistic missile capabilities even if placed under moratorium for the next decade.

With these threats taken together, the globalized threat to U.S. vital national interests as a whole during 2016 rose one level to “high.”

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) largely represented by each service. We treated the United States’ nuclear capability as a separate entity given the truly unique elements that make it possible, from the weapons themselves to the supporting infrastructure that is fundamentally different from that which 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 the 2016 Index, the common theme across the services and the U.S. nuclear enterprise is one of force degradation resulting from many years of underinvestment, poor execution of modernization programs, and the negative effects of budget sequestration (cuts in funding) on readiness and capacity. While the military has been heavily engaged in operations, primarily in the Middle East but elsewhere as well, since September 11, 2001, experience is both ephemeral and context-sensitive. Valuable combat experience is lost over time as the servicemembers who individually gained experience leave the force, and it maintains direct relevance only for future operations of a similar type (e.g., counterinsurgency operations in Iraq are fundamentally different from major conventional operations against a state like Iran or China).

Thus, although the current Joint Force is experienced in some types of operations, it is still aged and shrinking in its capacity for operations.

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 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 “Weak.” The Army’s score remained “weak” for reasons similar to those cited in the 2016 Index. The Army has continued to trade end strength and modernization for improved readiness for current operations. However, accepting risks in these areas has enabled the Army to keep only one-third of its force at acceptable levels of readiness, and even for units deployed abroad, the Army has had to increase its reliance on contracted support to meet maintenance requirements. Budget cuts have affected combat units disproportionately: A 16 percent reduction in total end strength has led to a 32 percent reduction in the number of brigade combat teams and similar reductions in the number of combat aviation brigades. In summary, the Army is smaller, older, and weaker, a condition that is unlikely to change in the near future.
  • Navy as “Marginal.” The Navy’s readiness score increased from 2016 Index’s “marginal” to “strong,” but only by sacrificing long-term readiness to meet current operational demands. While the Navy is maintaining a moderate global presence, it has little ability to surge to meet wartime demands. Deferred maintenance has kept ships at sea but is also beginning to affect the Navy’s ability to deploy. With scores of “weak” in capability (due largely to old platforms and troubled modernization programs) and “marginal” in capacity, the Navy is currently just able to meet operational requirements. Continuing budget shortfalls in its shipbuilding account will hinder the Navy’s ability to improve its situation, both materially and quantitatively, for the next several years.
  • Air Force as “Marginal.” While its overall score remains the same as last year’s, the USAF’s accumulating shortage of pilots (700) and maintenance personnel (4,000) has begun to affect its ability to generate combat power. The Air Force possesses 1,159 tactical fighter aircraft, which normally would support a score of “very strong” for capacity, but the lack of ability to fly and maintain them, especially in a high-tempo/threat combat environment, means that its usable inventory of such aircraft is actually much smaller. This reduced ability is a result of funding deficiencies that also result in a lack of spare parts, fewer flying hours, and compromised modernization programs.
  • Marine Corps as “Marginal.” The Corps continues to deal with readiness challenges driven by the combined effects of high operational tempo and low levels of funding. At times during 2016, less than one-third of its F/A-18s, a little more than a quarter of its heavy-lift helicopters, and only 43 percent of its overall aviation fleet were available for operational employment. Pilots not already in a deployed status were getting less than half of needed flight hours. The Corps’ modernization programs are generally in good shape, but it will take several years for the new equipment to be produced and fielded. As was the case in preceding years, the Index assesses that the Corps has only two-thirds of the combat units that it actually needs, especially when accounting for expanded requirements that include cyber units and more crisis-response forces.
  • Nuclear Capabilities as “Marginal.” Modernization, testing, and investment in intellectual and talent underpinnings continue to be the chief problems facing America’s nuclear enterprise. Delivery platforms are good, but the force depends on a very limited set of weapons (in number of designs) and models that are quite old, in stark contrast to the aggressive programs of competitor states. Of growing concern is the “marginal” score for “Allied Assurance” at a time when Russia has rattled its nuclear saber in a number of recent provocative exercises; China has been more aggressive in militarily pressing its claims to the South and East China Seas; North Korea is heavily investing in a submarine-launched ballistic missile capability; and Iran has achieved a nuclear deal with the West that effectively preserves its nuclear capabilities development program for the foreseeable future.

In aggregate, the United States’ military posture is rated as “Marginal” and is trending toward “Weak,” a condition unchanged from the 2016 Index.

Overall, the 2017 Index concludes that the current U.S. military force is capable of meeting the demands of a single major regional conflict while also attending to various presence and engagement activities—something it is doing now and has done for the past two decades—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 consistent decline in funding and the consequent shrinking of the force over the past few years have placed it under significant pressure. Essential maintenance continues to be deferred; the availability of fewer units for operational deployments increases the frequency and length of deployments; and old equipment is being extended while programmed replacements are either delayed or beset by developmental difficulties.

The military services have continued to prioritize readiness for current operations by shifting funding to deployed or soon-to-deploy units at the expense of keeping units that are not deployed in “ready” condition; delaying, reducing, extending, or canceling modernization programs; and sustaining the reduction in size and number of military units. These choices and their resulting condition, driven by the lack of funding dedicated to defense, hazard America’s ability to secure its interests now and erode America’s ability to shape conditions to its advantage by assuring allies and deterring competitors.

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