An Assessment of U.S. Military Power

America is a global power with global interests, and its military is tasked with defending the country from attack and protecting its national interests on a correspondingly global scale. The United States therefore does not have the luxury of focusing only on one geographic area or narrow challenge to its interests. Its economy depends on global trade; it has obligations with many allies; and it must account for several major competitors that routinely, consistently, and aggressively challenge its interests and seek to displace its influence in key regions. It follows that its military should be commensurately sized for the task and possess the necessary tools, skills, and readiness for action. Beyond that, the U.S. military must be capable of protecting the freedom to use the global commons—the sea, air, space, and cyberspace domains on which American prosperity and political influence depend.

As noted in all preceding editions of the Index of U.S. Military Strength, however, the U.S. does not have the necessary force to address more than one major regional contingency (MRC) and is not ready to carry out its duties effectively. In fact, its condition has worsened over the past two to three years.

• The U.S. finds itself increasingly challenged both by major competitors such as China and Russia and by the destabilizing effects of terrorist and insurgent elements operating in regions that are of substantial interest to the U.S.
• Russia’s large-scale, conventional invasion of Ukraine in February 2022 and the war that has ravaged Ukraine since then are proof that war in regions of interest to the U.S. remains a feature of modern times—something that is not lost on China as it expands its military power and threatens Japan and other U.S. allies and partners in the Indo-Pacific region more aggressively.
• Poland, Germany, Lithuania, Japan, and several other countries have taken note of this and are committed to substantially improving the capacity, capability, and readiness of their military forces, although progress has been spotty. The United States, however, has not made a similar commitment and has seen further decline as inflation has eroded the funding that is provided to the military.

How to Think About Sizing Military Power

Military power consists of many things and is the result of how all of its constituent pieces are brought together to create an effective warfighting force, but it begins with the people and equipment used to conduct war: the weapons, tanks, ships, airplanes, and supporting tools that make it possible for a force to impose its will on another or to prevent such an outcome from happening, which is the point of deterrence.

However, simply counting the number of people, tanks, or combat aircraft that the U.S. possesses would be insufficient because it would lack context. For example, the U.S. Army might have 100 tanks, but to accomplish a specific military task, 1,000 or more might be needed or none at all. It might be that relevant terrain is especially ill-suited to tanks or that the tanks one has are inferior to the enemy’s. The enemy could be quite adept at using tanks, or his tank operations might be integrated into a larger employment concept that leverages the supporting fires of infantry and airpower, whereas one’s own tanks are poorly maintained, the crews are not well prepared, or one’s doctrine is irrelevant.

Success in war is partly a function of matching the tools of warfare to a specific task and employing those tools effectively in battle. Get these wrong—tools, objective, competence, or context—and you lose.

Another key element is the military’s capacity to conduct operations: how many of the right tools—people, tanks, planes, or ships—it has. One might have the right tools and know how to use them effectively but not have enough to win. Because one cannot know with certainty beforehand just when, where, against whom, and for what reason a battle might be fought, determining how much capability is needed is an exercise that requires informed but not certain judgment.

The war in Ukraine is a powerful illustration of this. By the numbers, Russia should have achieved a quick victory over the smaller, less modern Ukrainian military. For various reasons that include leadership, tactics, training, and resupply, the Ukrainians have performed much better than the Russians, who have performed poorly overall. And yet, in spite of its demonstrated incompetence, Russia’s much larger military has been able to sustain operations through its willingness to commit its vast reserves of munitions, equipment, and people to battle. Tactical and operational brilliance has its place, but so does sheer mass.

Further, two different combatants can use the same set of tools in radically different ways to quite different effects. The concept of employment matters. Concepts are developed to account for numbers, capabilities, material readiness, and all sorts of other factors that enable or constrain one’s actions, such as whether one fights alone or alongside allies, on familiar or strange terrain, or with a large, well-equipped force or a small, poorly equipped force. A thinking adversary will analyze his opponent for weaknesses or patterns of behavior and seek to develop techniques, approaches, and tools that exploit such shortfalls or predictable patterns—the asymmetries of war. One need not try to match an enemy tank for tank: In many cases, not trying is more effective.

This appears to be what China is doing. Having analyzed U.S. forces, the performance characteristics of U.S. platforms and weapons, and the geography and basing options affecting U.S. defense posture in the Indo-Pacific, China has invested heavily in shore-based long-range missiles, an extensive fleet of ships optimized for the local maritime environment, and a deepening inventory of guided munitions. China does not need a force that mirrors that of the U.S.: It is building a force that leverages the asymmetries between China’s situation and that of the United States.

All of these factors and a multitude of others affect the outcome of any military contest. Military planners attempt to account for them when devising requirements, developing training and exercise plans, formulating war plans, and advising the President in his role as Commander in Chief of U.S. military forces.

Measuring hard combat power in terms of its capability, capacity, and readiness to defend U.S. vital interests is difficult, especially in such a limited space as this Index, but not impossible. However difficult the task, the Secretary of Defense and the military services have to make such decisions every year when the annual defense budget request is submitted to Congress.

The adequacy of hard power is affected most directly by the resources the nation is willing to apply. Although that decision is informed to a significant degree by an appreciation of threats to U.S. interests and the ability of a given defense portfolio to protect U.S. interests against such threats, it is not informed solely by such considerations; hence the importance of clarity and honesty in determining exactly what is needed in terms of hard power and the status of such power from year to year.

Administrations take various approaches in determining the type and amount of military power needed and, by extension, the amount of money and other resources that will be necessary to support that power. After defining the national interests to be protected, the Department of Defense (DOD) can use worst-case scenarios to determine the maximum challenges the U.S. military might have to overcome. Another way is to redefine what constitutes a threat. By taking a different view of whether major actors pose a meaningful threat and of the extent to which friends and allies have the ability to assist the U.S. in meeting security objectives, one can arrive at very different conclusions about the necessary level of military strength.

For example, one Administration might view China as a rising belligerent power bent on dominating the Asia–Pacific region. Another Administration might view China as an inherently peaceful rising economic power and the expansion of its military capabilities as naturally commensurate with its strengthening status. There can be dramatically different perspectives with respect to how China might use its military power and what would constitute an effective U.S. response, and the difference between these perspectives can dramatically affect how one thinks about U.S. defense requirements. So, too, can policymakers amplify or downplay risk to justify defense budget decisions.

There also can be strongly differing views on requirements for operational capacity.

• Does the country need enough for two major combat operations (MCOs) at roughly the same time or just enough for a single major operation and some number of lesser cases?
• To what extent should “presence” tasks—the use of forces for routine engagement with partner countries or simply to be on hand in a region for crisis response—be in addition to or a subset of a military force that is sized to handle big wars?
• How much value should be assigned to advanced technologies as they are incorporated into the force, especially if they have not been proven in combat settings?
• What is the likelihood of conventional war, and (if one thinks it is minimal) what level of risk is one willing to accept that sufficient warning will allow for rearming?

Where to Start

There are two major references that one can use to help sort through the variables and arrive at a starting point for assessing the adequacy of today’s military posture: government studies and historical experience. The government occasionally conducts formal reviews that are meant to inform decisions on capabilities and capacities across the Joint Force relative to the threat environment (current and projected) and evolutions in operating conditions, the advancement of technologies, and aspects of U.S. interests that may call for one type of military response over another.

The 1993 Bottom-Up Review (BUR) conducted by then-Secretary of Defense Les Aspin is one example that is frequently cited by analysts. Secretary Aspin recognized that “the dramatic changes that [had] occurred in the world as a result of the end of the Cold War and the dissolution of the Soviet Union” had “fundamentally altered America’s security needs” and were driving an imperative “to reassess all of our defense concepts, plans, and programs from the ground up.”1

The BUR formally established the requirement that U.S. forces should be able “to achieve decisive victory in two nearly simultaneous major regional conflicts and to conduct combat operations characterized by rapid response and a high probability of success, while minimizing the risk of significant American casualties.”2 Thus was formalized the two-MRC standard.

Since that study, the government has undertaken others as Administrations, national conditions, and world events have changed the context of national security. Quadrennial Defense Reviews (QDRs) were conducted in 1997, 2010, and 2014 and were accompanied by independent National Defense Panel (NDP) reports that reviewed and commented on them. Both sets of documents purported to serve as key assessments, but analysts came to minimize their value, regarding them as justifications for executive branch policy preferences (the QDR reports) or overly broad generalized commentaries (the NDP reports) that lack substantive discussion about threats to U.S. interests, a credible strategy for dealing with them, and the actual ability of the U.S. military to meet national security requirements.

The QDR was replaced by the National Defense Strategy (NDS), released in 2018,3 and the independent perspectives of the formal DOD review by the National Defense Strategy Commission, which released its view of the NDS in November 2018.4 Departing from their predecessors, neither document proposed specific force structures or end strength goals for the services, but both were very clear in arguing that America’s military should be able to address more than one major security challenge at a time. The commission’s report even criticized the NDS for not making a stronger case for a larger military that would be capable of meeting the challenges posed by four named competitors—China, Russia, Iran, and North Korea—while also possessing the capacity to address lesser, though still important, military tasks that included presence, crisis response, and assistance missions.

The Biden Administration released a National Defense Strategy in 20225 (replacing the Trump Administration’s 2018 NDS) in conjunction with its overarching National Security Strategy (NSS).6 The 2022 NDS echoes the general goal for the U.S. military to “deter and prevent adversaries from directly threatening the United States and our allies, inhibiting access to the global commons, or dominating key regions,”7 all of which are themes that have remained remarkably consistent from one Administration to the next for several decades. Taken at face value and considering the challenges posed simultaneously by a multitude of competitors in several regions, the Biden NSS and NDS imply that the military should have the capability and capacity to meet this objective, but they are less explicit than predecessor documents.

The current NSS and NDS prioritize the threat posed by China but, while naming other threats that include Russia, Iran, North Korea, and violent extremist organizations, purport to deal with them by improved forward posture of U.S. forces, improving national resilience to attack, and bettering the ability of the U.S. to collaborate with regional allies. Whether one agrees with the efficacy of this approach or not, there is consistency even in the current leading documents in acknowledging that the U.S. must contend with numerous threats to its interests in many different regions.8

Correlation of Forces as a Factor in Force Sizing

During the Cold War, the U.S. used the Soviet threat as its primary reference in determining its hard-power needs. At that time, the correlation of forces—a comparison of one force against another to determine strengths and weaknesses—was highly symmetrical. U.S. planners compared tanks, aircraft, and ships against their direct counterparts in the opposing force. These comparative assessments drove the sizing, characteristics, and capabilities of fleets, armies, and air forces.

The evolution of guided, precision munitions and the rapid technological advancements in surveillance and targeting systems since the late 1980s have made comparing combat power more difficult. What was largely a platform-versus-platform model has shifted to a munitions-versus-target model. Evidence of this has been seen on recent battlefields in Nagorno–Karabakh and Ukraine.

The proliferation of precise weaponry means increasingly that each round, bomb, rocket, missile, and even (in some instances) individual bullet can hit its intended target, thus decreasing the number of munitions needed to prosecute an operation. It also means that an operating environment’s lethality increases significantly for the people and platforms involved. We have reached the point at which, instead of focusing primarily on how many ships or airplanes the enemy can bring to bear against one’s own force, one must consider how many “smart munitions” the enemy has when thinking about how many platforms and people are needed to win a combat engagement.9 The increasing presence of unmanned systems that can deliver precision-guided munitions against targets adds complexity and danger to the modern battlefield. There is also the higher cost of fielding precision weapons rather than less expensive but also less accurate conventional (unguided) munitions.

In one sense, increased precision and the technological advances now being incorporated into U.S. weapons, platforms, and operating concepts make it possible to do far more than ever before with fewer assets.

• Signature reduction (stealth) makes it harder for the enemy to find and target platforms, and the increased precision of weapons makes it possible for fewer platforms, when carrying such weapons, to hit many more targets.
• The U.S. military’s ability to harness computers, modern telecommunications, space-based platforms—such as for surveillance, communications, and positioning-navigation-timing (PNT) support from GPS satellites—and networked operations potentially means that in certain situations, smaller forces can have far greater effect in battle than was possible at any other time in history (although these same advances also enable enemy forces).
• Some military functions—such as seizing, holding, and occupying territory—may require a certain number of soldiers no matter how state-of-the-art their equipment may be. For example, the number of infantry squads needed to secure an urban area where line of sight is constrained and precision weapons have limited utility is the same as the number needed in World War II. Again, current operations in Ukraine are illustrative as Russian forces have found that seizing, occupying, and holding ground is a manpower-intensive effort.

Regardless of the improved capability of smaller forces, there is a downside to fewer numbers. With smaller forces, each element of the force represents a greater percentage of its combat power. Each casualty or equipment loss therefore takes a larger toll on the ability of the force to sustain high-tempo, high-intensity combat operations over time, especially if the force is dispersed across a wide theater or multiple theaters of operation.

As advanced technology has become more affordable, it has become more accessible for nearly any actor, whether state or non-state.10 Consequently, it may well be that the outcomes of future wars will depend far more on the skill of the forces and their capacity to sustain operations over time than they will on some great disparity in technology. If so, readiness and capacity will become more important than absolute advances in capability.

All of this illustrates both the need to exercise judgment in assessing the adequacy of America’s military power and the difficulties involved in exercising that judgment. Yet without such an assessment, all that remains are the defense strategy reviews, which are subject to filtering and manipulation to suit policy interests; annual budget submissions, which typically favor desired military programs at presumed levels of affordability and are therefore necessarily budget-constrained; and leadership posture statements, which often simply align with executive branch policy priorities.

The U.S. Joint Force and the Art of War

This section of the Index assesses the adequacy of America’s defense posture as it pertains to a conventional understanding of hard power, defined as the ability of U.S. military forces to engage and defeat an enemy’s forces in battle at a scale commensurate with America’s vital national interests. While some hard truths in military affairs are appropriately addressed by mathematics and science, others are not. Speed, range, probability of detection, and radar cross-section are examples of quantifiable characteristics that can be measured. Specific future instances in which U.S. military power will be needed, the competence of the enemy, the political will to sustain operations in the face of mounting deaths and destruction, and the absolute amount of strength needed to win are matters of judgment and experience, but they nevertheless affect how large and capable a force one might need.

In conducting our assessment, we accounted for both quantitative and qualitative aspects of military forces, informed by an experience-based understanding of military operations and the expertise of external reviewers. The authors of these military sections bring a combined total of more than a hundred years of uniformed military experience to their analysis.

Military effectiveness is as much an art as it is a science. Specific military capabilities represented in weapons, platforms, and military units can be used individually to some effect, but practitioners of war have learned that combining the tools of war in various ways and orchestrating their tactical employment in series or simultaneously can dramatically amplify the effectiveness of the force that is committed to battle.

Employment concepts are exceedingly hard to measure in any quantitative way, but their value as critical contributors in the conduct of war is undeniable. How they are used is very much an art-of-war matter that is learned through experience over time.

What Is Not Being Assessed

In assessing the current status of America’s military forces, this Index uses the primary measures used by the military services themselves when they discuss their ability to employ hard combat power.

• The Army’s unit of measure is the brigade combat team (BCT).
• The Marine Corps structures itself by battalions.
• For the Navy, it is the number of ships in its combat fleet.
• The most consistent measure for the Air Force is the total number of aircraft, sometimes broken down into the two primary subtypes of fighters and bombers.

Obviously, this is not the totality of service capabilities, and it certainly is not everything needed for war. Even the services would argue that “what they bring to the fight” is more than these simple metrics. But discussions about the complexity, nuance, and permutations of military power that take place among career professionals are endless and can be incomprehensible to most people who have not spent years closely studying such issues. Nevertheless, measures must be found by which to discuss military power in common terms, and these measures can be viewed as surrogates that subsume or represent the vast number of other things that make these units of measure possible and effective in battle. For example:

• Combat forces depend on a vast logistics system that supplies everything from food and water to fuel, ammunition, and repair parts.
• Military operations require engineer support, and the force needs medical, dental, and administrative capabilities.
• The military also fields units that transport combat power and its sustainment to wherever they may be needed around the world.

The point is that the military spear has a great deal of shaft that makes it possible for the tip to locate, close with, and destroy its target, and there is a rough proportionality between shaft and tip. Thus, in assessing the basic units of measure for combat power, one can get a sense of what is probably needed in the combat support, combat service support, and supporting establishment echelons.

The scope of this Index does not extend to analysis of everything that makes hard power possible; it focuses on the status of the hard power itself. It also does not assess the services’ Reserve and National Guard components, although they account for roughly one-third of the U.S. military force and have been essential to the conduct of operations since September 2001.11 Consistent assessment of their capability, readiness, and operational role is challenging because each service determines the balance among its Active, Reserve, and National Guard elements differently: Only the Army and Air Force have Guard elements; the Navy and Marine Corps do not. This balance can change from year to year and is based on factors that include the respective elements’ costs, availability for operational employment, and time needed to respond to an emergent crisis as well as the allocation of roles among the elements and political considerations.12

As with other elements that are essential to the effective employment of combat power—logistics, medical support, strategic lift, training, etc.—the U.S. military could not handle a major conflict without the Reserve and Guard forces. Nevertheless, to make the challenge of annually assessing the status of U.S. military strength using consistent metrics over time more manageable, this Index looks at something that is usually associated with the Active component of each service: the baseline requirement for a given amount of combat power that is readily available for use in a major combat operation. There are exceptions, however. For example, in the 2020 Index, four Army National Guard BCTs were counted as “available” for use because of the significant amounts of additional resources that had been dedicated specifically to these formations to raise their readiness levels.13

The Defense Budget and Strategic Guidance

How much we spend on defense does not automatically determine the U.S. military’s posture or capacity. As a matter of fact, simply looking at how much is allocated to defense does not tell us much about the capacity, modernity, or readiness of the forces. Proper funding is a necessary condition for a capable, modern, and ready force, but it is not sufficient by itself. A larger defense budget, for example, can be associated with less military capability if the money is allocated inappropriately or spent wastefully. Nevertheless, the budget does reflect the importance assigned to defending the nation and its interests in prioritizing federal spending, and there is a rough correlation between the percentage of the federal budget or national gross domestic product that is spent on defense and the military’s status because costs for equipment, personnel, and readiness tend to reflect general costs across the economy and the evolution of new technologies and materials that are harnessed for military affairs.

Absent a significant threat to the country’s survival, the U.S. government will always balance spending on defense against spending in all of the other areas of government activity that are deemed necessary or desirable. Ideally, defense requirements are determined by identifying national interests that might need to be protected with military power; assessing the nature of threats to those interests, what would be needed to defeat those threats, and the costs associated with that capability; and then determining what the country can afford or is willing to spend. Any difference between assessed requirements and the amount of money actually spent on defense would constitute a risk to U.S. security interests.

This Index enthusiastically adopts this approach: interests, threats, requirements, resulting force, and associated budget. Spending less than the amount needed to maintain a two-MRC force results in policy debates about where to accept risk: force modernization, the capacity to conduct large-scale or multiple simultaneous operations, or force readiness. The composition of the force and the understanding of military risk have become more salient issues with the shift toward competition with China and Russia. Certainly, Russia’s war against Ukraine has revealed the reality of war in its appetite for resources and the relative effectiveness of military units possessing various types of equipment, munitions inventories, and histories of training.

Assessments of potential conflict between the U.S. and Russia or China tend toward theory in peacetime and can underestimate what would be needed to prevail in war. War in its reality can be not just illuminating, but shocking when compared to peacetime estimates. The 2017 National Security Strategy,14 2021 Interim National Security Strategic Guidance,15 2022 National Security Strategy,16 and 2022 National Defense Strategy17 all have recognized that meeting the challenges posed by these two large, well-equipped, and well-resourced countries requires a U.S. force that is modern, ready, and effective in all domains of warfare.

Fiscal year (FY) 2023 continued the Biden Administration’s trend of increasing non-defense spending at a higher rate than defense spending. The Administration initially requested $773 billion for the DOD base discretionary budget, which was a 4.1 percent increase over the previous fiscal year’s budget.18 Continuing a trend from the previous year, this relative frugality stood in contrast to the substantially larger increases requested for other federal agencies with requests for non-defense funding rising 10 percent across the board.19

Congressional leaders saw the Administration’s proposal as inadequate, and both chambers acted through the appropriations and authorization bills to increase the defense budget by $45 billion over the requested amount in order to counter the effects of inflation and accelerate implementation of the National Defense Strategy.20 This increase represented both a rejection of platform retirements proposed by the Biden Administration and Congress’s assessment of what is needed to tackle the challenges and threats faced by our armed forces. For example, the munitions industrial base was strengthened by congressional additions both through additional funding and through the authority to enter into multi-year contracts.

The FY 2023 DOD base discretionary budget was $816.7 billion.21 This represents the resources allocated to pay for America’s military forces (manpower, equipment, and training); their enabling capabilities (things like transportation, satellites, defense intelligence, and research and development); and their institutional support (bases and stations, facilities, recruiting, and the like).

With the congressional increase, the FY 2023 defense budget was 8 percent higher in nominal terms than the FY 2022 budget.22 Unfortunately, as in FY 2022, the nation continued to experience levels of inflation in FY 2023 that it had not experienced for 40 years: Despite falling from the massive 7 percent to 9 percent rates experienced in FY 2022, inflation in the middle of FY 2023 still stood at around 4 percent.23 By increasing fuel, food, raw materials, and labor costs, inflation affects the defense budget as much as it does any household budget. Therefore, the price of merely maintaining our current force structure has risen considerably in the past year and is likely to rise further in the coming years as inflation continues to raise costs.

Adding to these challenges, part of the federal government’s response to the coronavirus pandemic was a substantial increase in government spending. Federal outlays jumped from $4.4 trillion in 2019 to $6.8 trillion in 2021, and the result was a $3.1 trillion budgetary deficit in FY 2020 and a $2.7 trillion deficit in FY 2021.24 Federal deficit spending was roughly $1.4 trillion for FY 2022 and $1.2 trillion for FY 2023—lower than it was during the coronavirus pandemic but hundreds of billions more than it had been in pre-pandemic 2019. This extremely high level of budgetary deficit should shape how the country assesses the federal government’s budgetary priorities, especially when added to a national debt that had reached $32 trillion during FY 2023.25 The public debt, which has been building for years, will continue to consume federal taxpayers’ dollars and will have to be balanced against all other federal priorities.

The decision to fund national defense at a level that is commensurate with interests and prevailing threats reflects our national priorities and risk tolerance. This Index assesses the ability of the nation’s military forces to protect vital national security interests within the world as it is so that the debate about the level of funding for hard power is better informed.

Purpose as a Driver in Force Sizing

The Joint Force is used for a wide range of purposes, only one of which is major combat operations. Fortunately, such events have been relatively rare, although they have occurred every 15 years on average.26 In between (and even during) such occurrences, the military is used to support regional engagement, crisis response, strategic deterrence, and humanitarian assistance as well as to support civil authorities and U.S. diplomacy.

All of the U.S. Unified Geographic Combatant Commands, or COCOMS27—Northern Command (NORTHCOM); European Command (EUCOM); Central Command (CENTCOM); Indo-Pacific Command (INDOPACOM); Southern Command (SOUTHCOM); and Africa Command (AFRICOM)—have annual and long-term plans for engaging with countries in their assigned regions. Engagements range from very small unit training events with the forces of a single partner country to larger bilateral and sometimes multilateral military exercises. Such events help to foster working relationships with other countries, acquire a more detailed understanding of regional political–military dynamics and on-the-ground conditions in areas of interest, and signal U.S. security interests to friends and competitors.

To support such COCOM efforts, the services provide forces that are based permanently in their respective regions or that operate in them temporarily on a rotational basis. To make these regional rotations possible, the services must maintain base forces that are large enough to train, deploy, support, receive back, and again make ready a stream of units that ideally is enough to meet validated COCOM demand.

The ratio between time spent at home and time spent away on deployment for any given unit is known as OPTEMPO (operational tempo), and each service attempts to maintain a ratio that both gives units enough time to educate, train, and prepare their forces and allows the individuals in a unit to maintain some semblance of a healthy home and family life. This ensures that units are fully prepared for the next deployment cycle and that servicemembers do not become “burned out” or suffer adverse consequences in their personal lives because of excessive deployment time.

Experience has shown that a ratio of at least 3:1 (three periods of time at home for every period deployed) is sustainable. If a unit is to be out for six months, for example, it will be home for 18 months before deploying again. Obviously, a service needs enough people, units, ships, and planes to support such a ratio. If peacetime engagement were the primary focus for the Joint Force, the services could size their forces to support these forward-based and forward-deployed demands. Thus, the size of the total force must necessarily be much larger than any sampling of its use at any point in time.

In contrast, sizing a force for major combat operations is an exercise informed by history—how much force was needed in previous wars—and then shaped and refined by analysis of current threats, a range of plausible scenarios, and expectations about what the U.S. can do given training, equipment, employment concept, and other factors. The defense establishment must then balance “force sizing” between COCOM requirements for presence and engagement and the amount of military power (typically measured in terms of combat units and major combat platforms, which inform total end strength) that is thought necessary to win in likely war scenarios.

Inevitably, compromises are made that account for how much military the country is willing to buy. Generally speaking:

• The Army sizes to major warfighting requirements.
• The Marine Corps focuses on crisis response demands and the ability to contribute to one major war.
• The Air Force attempts to strike a balance that accounts for historically based demand across the spectrum because air assets are shifted fairly easily from one theater of operations to another (“easily” being a relative term when compared to the challenge of shifting large land forces), and any peacetime engagement typically requires some level of air support.
• The Navy is driven by global presence requirements. To meet COCOM requirements for a continuous fleet presence at sea, the Navy must have three to four ships in order to have one on station. A commander who wants one U.S. warship stationed off the coast of a hostile country, for example, needs the use of four ships from the fleet: one on station, one that left station and is traveling home, one that just left home and is traveling to station, and one that is otherwise unavailable because of major maintenance or modernization work.

This Index focuses on the forces required to win two major wars as the baseline force-sizing metric for the Army, Navy, and Air Force and the one-war-plus-crisis-response paradigm for the Marine Corps. The three large services are sized for global action in more than one theater at a time; the Marines, by virtue of overall size and most recently by direction of the Commandant, focus on one major conflict while ensuring that all Fleet Marine Forces are globally deployable for short-notice, smaller-scale actions.28 The military’s effectiveness, both as a deterrent against opportunistic competitor states and as a valued training partner in the eyes of other countries, derives from its effectiveness (proven or presumed) in winning wars.

Our Approach

With this in mind, we assessed the state of America’s military forces as it pertains to their ability to deliver hard power against an enemy in three areas:

• Capability,
• Capacity, and
• Readiness.

Capability. Examining the capability of a military force requires consideration of:

• The proper tools (material and conceptual) with the design, performance characteristics, technological advancement, and suitability that the force needs to perform its function against an enemy successfully.
• The sufficiency of armored vehicles, ships, airplanes, and other equipment and weapons to win against the enemy.
• The appropriate variety of options to preclude strategic vulnerabilities in the force and give flexibilities to battlefield commanders.
• The degree to which elements of the force reinforce each other in covering potential vulnerabilities, maximizing strengths, and gaining greater effectiveness through synergies that are not possible in narrowly stovepiped, linear approaches to war.

The capability of the U.S. Joint Force was on ample display in its decisive conventional war victory over Iraq in liberating Kuwait in 1991 and later in the conventional military operation in Iraq to depose Saddam Hussein in 2003. Aspects of its capability have also been seen in numerous other operations undertaken since the end of the Cold War. While the conventional combat aspect of power projection has been more moderate in places like Yugoslavia, Somalia, Bosnia and Serbia, Kosovo, and even against the Taliban in Afghanistan in 2001, the fact that the U.S. military was able to conduct highly complex operations thousands of miles away in austere, hostile environments and sustain those operations as long as required is testament to the ability of U.S. forces to do things that the armed forces of few if any other countries can do.

The most recent evidence of this was seen in the hasty evacuation of civilians from Afghanistan in August 2021 once the Biden Administration ordered the end of U.S. operations in that country. Though subject to severe criticism both during and after its execution, almost all of which had to do with the politics surrounding the decision to withdraw and the context that framed the nature of the operation, the operation itself was an extraordinary feat of military effectiveness within tight time constraints and tremendous pressure. Approximately 124,000 civilians were evacuated via the Hamid Karzai International Airport, situated on the outskirts of Kabul, during the latter two weeks of August. The effort involved 6,000 troops on the ground and approximately 800 aircraft from 30 countries (250 of which were U.S. Air Force transports), all coordinated and controlled by U.S. military personnel.29 No other country could have executed such a mission under such conditions.

A modern “major combat operation”30 along the lines of those upon which Pentagon planners base their requirements would feature a major opponent possessing modern integrated air defenses; naval power (surface and undersea); advanced combat aircraft (to include bombers); a substantial inventory of short-range, medium-range, and long-range missiles; current-generation ground forces (tanks, armored vehicles, artillery, rockets, and anti-armor weaponry); cruise missiles; and (in some cases) nuclear weapons. Such a situation involving an actor capable of threatening vital national interests would present a challenge that is comprehensively different from the challenges that the U.S. Joint Force has faced in past decades.

Since 2018, given its focus on counterinsurgency, stability, and advise-and-assist operations since 2004 and the 2018 NDS directive to prepare for conflict in an era of great-power competition, the military community has focused on its suitability and readiness for major conventional warfare.31 In general terms, this focus has been sustained through the release of the 2022 NDS, perhaps spurred by the observed realities of the Russia–Ukraine war and China’s rapid expansion of its military capabilities and activities.

• The Army in particular has noted the need to reengage in training and exercises that feature larger-scale combined arms maneuver operations, especially to ensure that its higher headquarters elements are up to the task.
• The Marine Corps has undertaken a dramatic restructuring to posture itself more effectively for high-end warfare against a major opponent, focusing specifically on China and the littorals of the Indo-Pacific but also appreciating that its new capabilities will be broadly applicable elsewhere.
• Both the Navy and the Air Force have acknowledged the evolved threat environment that will demand more of them in the coming decade than they have had to deal with during the past 20 years.

This Index ascertains the relevance and health of military service capabilities by looking at such factors as the average age of equipment, the generation of equipment relative to the current state of competitor efforts as reported by the services, and the status of replacement programs that are meant to introduce more updated systems as older equipment reaches the end of its programmed service life. While some of the information is quite quantitative, other factors could be considered judgment calls made by acknowledged experts in the relevant areas of interest or addressed by senior service officials when providing testimony to Congress or examining specific areas in other official statements.

It must be determined whether the services possess capabilities that are relevant to the modern combat environment.

Capacity. The U.S. military must have a sufficient quantity of the right capability or capabilities. When speaking of platforms such as planes and ships, a troubling and fairly consistent trend within U.S. military acquisition characterizes the path from requirement to fielded capability. Along the way to acquiring the capability, several linked things happen that result in far less of a presumed “critical capability” than was supposedly required.

• The military articulates a requirement that the manufacturing sector attempts to satisfy.
• “Unexpected” technological hurdles arise that take longer and much more money to solve than anyone envisioned.
• Programs are lengthened, and cost overruns are addressed, usually with more money.
• Then the realization sets in that the country either cannot afford or is unwilling to pay the cost of acquiring the total number of platforms originally advocated. The acquisition goal is adjusted downward, if not canceled altogether, and the military finally fields fewer platforms at a higher cost per unit than it originally said it needed to be successful in combat.

As deliberations proceed toward a decision on whether to reduce planned procurement, they rarely focus on and quantify the increase in risk that accompanies the decrease in procurement.

Something similar happens with force structure size: the number of units and total number of personnel the services say they need to meet the objectives established by the Commander in Chief and the Secretary of Defense in their strategic guidance.

• The Marine Corps has stated that it needs 27 infantry battalions to fully satisfy the validated requirements of the regional Combatant Commanders, yet it currently fields only 22 in order to make resources available for experimentation and modernization and to sustain its contributions to U.S. Special Operations Command (investing a regiment in Marine Forces Special Operations Command).32
• In 2012, the Army was building toward 48 brigade combat teams, but incremental budget cuts reduced that number over time to 31—less than two-thirds the number that the Army originally thought was necessary.
• The Navy has produced various assessments of fleet size since the end of the Cold War, from 313 ships to 372 ships with some working estimates as high as 500 manned ships.

Older equipment can be updated with new components to keep it relevant, and commanders can employ fewer units more expertly for longer periods of time in an operational theater to accomplish an objective. At some point, however, sheer numbers of updated, modern equipment and trained, fully manned units are going to be needed to win in battle against a credible opponent when the crisis is profound enough to threaten a vital national interest.

Capacity (numbers) can be viewed in at least three ways:

• Compared to a stated objective for each category by each service,
• Compared to amounts required to complete various types of operations across a wide range of potential missions as measured against a potential adversary, and
• As measured against a set benchmark for total national capability.

This Index employs the two-MRC metric as a benchmark for most of the force. This benchmark is the minimum standard for U.S. hard-power capacity because one will never be able to employ 100 percent of the force at any given time. Some percentage of the force will always be unavailable because of long-term maintenance overhaul, especially for Navy ships; unit training cycles; employment in myriad engagement and small-crisis response tasks that continue even during major conflicts; a standing commitment with allies to maintain U.S. forces in a given country or region; and the need to keep some portion of the force uncommitted to serve as a strategic reserve.

The historical record shows that, on average, the U.S. Army commits 21 BCTs to a major conflict; thus, a two-MRC standard would require that 42 BCTs be available for actual use. But an Army built to field only 42 BCTs would also be an Army that could find itself entirely committed to war, leaving nothing back as a strategic reserve to replace combat losses or to handle other U.S. security interests. Although new technologies and additional capabilities have made current BCTs more capable than those they replaced, one thing remains the same: Today’s BCT, like its predecessors, can be committed only to one place at a time and must be able to account for combat losses, especially if it engages a similarly modernized enemy force. Thus, regardless of modernity, numbers still matter.

Again, this Index assesses only the Active component of the service, albeit with full awareness that the Army also has Reserve and National Guard components that together account for half of the total Army. The additional capacity needed to meet these “above two-MRC requirements” could be handled by these other components or mobilized to supplement Active-component commitments. In fact, this is how the Army thinks about meeting operational demands and is at the heart of the long-running debate within the total Army about the roles and contributions of its various components. A similar situation exists within the Air Force and Marine Corps.

The balance among Active, Reserve, and Guard elements is beyond the scope of this study. Our focus is on establishing a minimum benchmark for the capacity needed to handle a two-MRC requirement.

We conducted a review of the major defense studies (1993 BUR, QDR reports, and independent panel critiques) that are publicly available,33 as well as modern historical instances of major wars (Korea, Vietnam, Gulf War, Operation Iraqi Freedom), to see whether there was any consistent trend in U.S. force allocation. The results of our review are presented in Table 6. To this we added 20 percent, both to account for forces and platforms that are likely to be unavailable and to provide a strategic reserve to guard against unforeseen demands.

Summarizing the totals, this Index concluded that a Joint Force capable of dealing with two MRCs simultaneously or nearly simultaneously would consist of:

• Army: 50 BCTs.
• Navy: at least 400 ships and 624 strike aircraft.
• Air Force: 1,200 fighter/attack aircraft.
• Marine Corps: 30 battalions.

America’s security interests require that the services have the capacity to handle two major regional conflicts successfully.

Readiness. The consequences of the sharp reductions in funding mandated by sequestration from 2011 until 2021 caused military service officials, senior DOD officials, and even Members of Congress to warn of the dangers of recreating the “hollow force” of the 1970s when units existed on paper but were staffed at reduced levels, minimally trained, and woefully ill-equipped.34 To avoid this, the services traded quantity/capacity and modernization to ensure that what they do have is “ready” for employment.

Supplemental funding in FY 2017, a higher topline in FY 2018, and sustained increases in FY 2019 and FY 2020 helped to stop the bleeding and enabled the services to plan and implement readiness recovery efforts. Massive federal spending in response to the COVID-19 pandemic in calendar years 2020 and 2021 led to fiscal pressure on defense accounts in future years, but gains in readiness were preserved during FY 2020.

Ensuring adequate readiness in FY 2021 was difficult given the challenges created by COVID-19 during the preceding year. In FY 2022, the services continued their effort to find an appropriate balance among capability, capacity, and readiness, at first benefiting from a reduction in combat operations and the easing of COVID-​related restrictions and disruptions but then forced to contend with a loss in spending power caused by rising inflation. Continuing inflationary problems presented a new budgeting challenge to the services with the dramatic spike in interest rates, which increased from 0.0 percent–0.25 percent in FY 2022 to as high as 5.0 percent–5.25 percent in FY 2023.35

It is one thing to have the right capabilities to defeat the enemy in battle. It is another thing to have enough of those capabilities to sustain operations and many battles against an enemy over time, especially when attrition or dispersed operations are significant factors. But sufficient numbers of the right capabilities are rather meaningless if the force is not ready to engage in the task.

Scoring. In our final assessments, we tried very hard not to convey a higher level of precision than we think is achievable using unclassified, open-source, publicly available documents; not to reach conclusions that could be viewed as based solely on assertions or opinion; and not to rely solely on data and information that can be highly quantified. Simple numbers, while important, do not tell the whole story.

We believe that the logic underlying our methodology is sound. This Index draws from a wealth of public testimony from senior government officials, from the work of recognized experts in the defense and national security analytic community, and from historical instances of conflict that seemed most appropriate to this project. It then considers several questions, including:

• How does one place a value on the combat effectiveness of such concepts as Air-Sea Battle, Multi-Domain Operations, Littoral Operations in a Contested Environment, Distributed Maritime Operations, Network-centric Operations, or Joint Operational Access when they have not been tested in battle?36
• Is it entirely possible to assess accurately (1) how well a small number of newest-generation ships or aircraft will fare against a much larger number of currently modern counterparts when (2) U.S. forces are operating thousands of miles from home, (3) orchestrated with a particular operational concept, and (4) the enemy is leveraging a “home field advantage” that includes strategic depth and much shorter and perhaps better protected lines of communication and (5) might be pursuing much dearer national objectives than the U.S. is pursuing so that the political will to conduct sustained operations in the face of mounting losses might differ dramatically?
• How does one neatly quantify the element of combat experience, the erosion of experience as combat operation events recede in time and those who participated in them leave the force, the health of a supporting workforce, the value of “presence and engagement operations,” and the related force structures and patterns of deployment and employment that presumably deter war or mitigate its effects if it does occur?

New capabilities such as unmanned systems, cyber tools, hypervelocity platforms and weapons, and the use of artificial intelligence to achieve a better understanding of operations and orchestrate them more effectively have the potential to change military force posture calculations. At the present time, however, they are not realized in any practical sense.

This Index is focused on the primary purpose of military power—to defeat an enemy in combat—and the historical record of major U.S. engagements for evidence of what the U.S. defense establishment has thought was necessary to execute a major conventional war successfully. To this we added the two-MRC benchmark; on-the-record assessments of what the services themselves are saying about their status relative to validated requirements; and the analysis and opinions of various experts, both in and out of government, who have covered these issues for many years.

Taking everything together, we rejected scales that would imply extraordinary precision and settled on a scale that conveys broader characterizations of status that range from very weak to very strong. Ultimately, any such assessment is a judgment call informed by quantifiable data, qualitative assessments, thoughtful deliberation, and experience. We trust that our approach makes sense, is defensible, and is repeatable.

Endnotes