As currently postured, the U.S. military is at significant risk of not being able to defend America’s vital national interests. This is the inevitable result of years of prolonged deployments, underfunding, poorly defined priorities, wildly shifting security policies, exceedingly poor discipline in program execution, and a profound lack of seriousness across the national security establishment even as threats to U.S. interests have surged. In 2023, this has been compounded by the cost of U.S. support for Ukraine’s defense against Russia’s assault, which is further exacerbated by the limited willingness of allies in Europe to shoulder a greater share of the burden. The war has laid bare the limited inventories of equipment, munitions, and supplies of all supporting countries as well as the limitations of the industrial base that will be required to replenish them.
The United States maintains a military force to protect the homeland from attack and to safeguard its interests abroad. There obviously are other uses—for example, to assist civil authorities in times of emergency or to deter enemies—but this force’s primary purpose historically has been to make it possible for the U.S. to physically impose its will on an enemy in defense of our nation and its vital interests.
It is therefore critical that the American people understand 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” to protect them. Because changes can have substantial implications for defense policies and investment, knowing how these three areas change over time is likewise important. Of the three, however, the condition of the military is the one that we most need to understand because it is the only one over which the U.S. has complete control, and it underwrites the ability of all other aspects of national power to flourish or fail.
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 and that both assesses the state of affairs for its respective year and measures how key factors have changed during the preceding year. The current year can be compared to the initial year (2015) quite easily to see whether trends with respect to the U.S. military’s ability to defend America’s interests have been positive or negative.
The Index is not an assessment of what might be, although the trends that it captures may well imply both concerns and opportunities that can guide decisions that are germane to America’s security. Rather, the Index should be seen as a report card for how well or poorly conditions, countries, and the U.S. military have evolved during the assessed year. The past cannot be changed, but it can inform the present, just as the future cannot be predicted but can be shaped.
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. Assessments of threats are based on the behavior and physical capabilities of actors that pose challenges to vital U.S. 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. This framework provides a single-source reference for policymakers and other Americans who seek to know whether our military 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. Three vital interests have been specified consistently (albeit in varying language) 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: 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, Department of Defense staffs, and independent commissions have managed to arrive at a surprisingly consistent force-sizing rationale: an ability to handle two major conflicts simultaneously or in closely overlapping time frames. The validity of this rationale is amply demonstrated by the experience gained from the actual use of America’s military. As we find ourselves in a new cold war with China, it stands to reason that we need to restore the force structure that enabled the U.S. to prevail during the previous one with the Soviet Union.
At its root, the current National Defense Strategy (NDS) implies the same force requirement.1 Its emphasis on a return to long-term competition with major powers, explicitly naming Russia and China as primary competitors, 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 to 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 might wish that the world were a simpler, less threatening place, more inclined to beneficial economic interactions than to violence-laden friction, the patterns of history show that competing powers inevitably emerge and that the U.S. must be able to defend its interests in more than one region at a time. Russia’s invasion of Ukraine, China’s dramatic expansion of its military and its provocative behavior far beyond the Indo-Pacific region, North Korea’s intransigence with respect even to discussing its nuclear capabilities, and Iran’s dogged pursuit of a nuclear weapon capability and sustained support for terrorist groups illustrate this point. On October 7, 2023, Iranian-sponsored Hamas conducted a coordinated terrorist attack on Israel, claiming the lives of more than 1,400 Israelis and 33 Americans. This horrific attack marked the deadliest day in Israel’s history and the deadliest terrorist attack on Americans since September 11, 2001. Two Carrier Strike Groups, an Amphibious Readiness Group, a number of U.S. Air Force squadrons, and theater missile defense systems have been deployed in an attempt to restore deterrence and prevent regional escalation.
Given this range of potential and actual threats to U.S. interests in multiple regions, and given the inability to predict when any one threat or multiple threats may materialize, this Index therefore embraces the two-war or two-contingency requirement so that America will have the ability to respond to an emergent threat while retaining the capacity to respond to a second.
Since its founding, the U.S. has been involved in a major “hot” war every 15–20 years.2 Since World War II, the U.S. has also maintained substantial combat forces in Europe and other regions while simultaneously fighting major wars as circumstances demanded. The size of the total force roughly approximated the two-contingency model, which has the inherent ability to meet multiple security obligations to which the U.S. has committed itself 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.3
We recognize that extended periods of peace and prosperity can lead to complacency and that without a dramatic change in circumstances such as the onset of a major conflict, a multitude of competing interests that evolve during such periods will cause Administrations and Congresses to spend more on domestic programs and less on defense. The results, unfortunately, are predictable: a weakened military, emboldened competitors, and a nation at risk. Winning the support needed to increase defense spending to the level that a force with a two-war capacity requires is admittedly difficult politically, but this 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-war force is derived from a review of the forces used for each major war that the U.S. has undertaken since World War II, major defense studies completed by the federal government over the past 30 years, and the toll that extended use of military forces can exact even when the enemy is not a peer competitor. We conclude that a standing (Active Component) two-war–capable force would consist of:
- Army: 50 brigade combat teams (BCTs);
- Navy: 400 battle force ships and 624 strike aircraft;
- Air Force: 1,200 fighter/ground-attack aircraft;
- Marine Corps: 30 battalions; and
- Space Force: metric not yet established.
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 that are 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
The United States is a global power, which means that it also has global security interests and requires a military that is able to protect those interests anywhere they are threatened. While this may occur in any region, three regions—Europe, the Middle East, and Asia—stand apart because of the scale and scope of U.S. interests associated with them and the significance of competitors that are able to pose commensurately large threats. Aggregating the three regional scores provides a global operating environment score of “favorable” in the 2024 Index.
Europe. The duration of Russia’s war on Ukraine, its mounting cost and savagery, and the questions it poses for the future of Europe, NATO, and individual countries have forced European governments and Europeans generally to reexamine their political dynamics, economic dependence on other countries, and ability to provide for their own domestic security interests.
In the 2023 Index, we noted a strengthening in alliance relationships as NATO member countries conducted reviews of their respective military establishments and the ability of NATO, as a whole, to coordinate actions. NATO placed renewed emphasis on logistical matters and the extent to which it could respond to emergent crises.
During the past year, we have seen a galvanizing effect within political establishments that, while still dynamic within the domestic context of each country, appear generally to be more stable as countries take serious account of national matters that they have neglected since the end of the Cold War. Within specific countries, there are ongoing shifts between liberal and conservative governments, but the net result has been generally positive with respect to U.S. security interests, especially as countries commit to improving their defense capabilities, readiness, and postures. This has led us to increase Europe’s score for political stability from “favorable” to “excellent.”
However, although America’s relationships with European partners are generally sound and the political environment in many countries is healthy, the factors that quickly determine the ability of U.S. forces to operate are their positioning or presence on the continent and the physical infrastructure necessary to support military action. With these in mind, we score Europe as “favorable” for U.S. military activities should they be needed.
The Middle East. Efforts to integrate Iran into the region threaten regional stability, Israel’s security, and global markets. The convergence of threats encompasses an Iranian nuclear threshold state controlling a constellation of terrorist groups, resurgent non-state terrorist groups, and Russian and Chinese exploitation of a declining American presence. The United States risks the irrevocable loss of a favorable balance of both trade and forces and a resultant instability that threatens our vital national interests and the global economy. The October 7 attack on Israel and subsequent Iranian-sponsored attacks on U.S. forces in the region significantly enhance the risk of escalation. This risk represents an unprecedented range of challenges beyond our capacity and the capacity of our partners and allies to address threats to global energy and trade.
The Middle East is a vital component of the global economy. It accounts for 31 percent of global oil production, 18 percent of gas production, 48 percent of proven oil reserves, and 40 percent of proven gas reserves. Approximately 12 percent of global trade and 30 percent of global container traffic traverses the Suez Canal, transporting over $1 trillion worth of goods each year. In 2018, the Middle East’s daily oil flow constituted approximately 21 percent of global petroleum consumption. But the region’s significance is not limited to energy. Sixteen of the submarine cables that connect Asia and Europe pass through the Red Sea.
While the United States may no longer be dependent on the region’s petroleum, the global economy is.4 Beijing knows the Middle East is a vital source of the energy that fuels its economic growth and military; we cannot afford to ignore this critical vulnerability. China’s economy and military are exogenic, and this dependence resulted in the development of its Belt and Road Initiative (BRI) to obtain the resources it requires and sustain the routes that connect China to these resources.
Many of the borders in the region that were created after World War I are under significant stress. In countries like Iraq, Lebanon, Libya, Syria, and Yemen, the supremacy of the nation-state is being challenged by non-state actors that wield influence, power, and resources comparable to those of small states. 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, to which must be added the Arab–Israeli conflict, Sunni–Shia sectarian divides, the rise of Iran’s Islamist revolutionary nationalism, and the proliferation of Sunni Islamist revolutionary groups. In addition, the China-brokered rapprochement between Iran and Saudi Arabia and Beijing’s regionwide infrastructure investments are a warning to U.S. policymakers that neglect of long-standing allies leaves behind power vacuums that America’s enemies are only too capable of exploiting to their own advantage.
We have relied on our incomparable ability to project power in response to crises, and many of our operations and contingency plans depend on the time-phased force deployment from the continental U.S. to operations theaters. This requires secure air and sea lanes of communication as well as secure air and sea bases of debarkation. Neither is assured in a theater conflict as Iran now possesses the ability to threaten three of the region’s strategic choke points (the Strait of Hormuz, Bab al-Mandeb, and the Suez Canal) as well as our bases and ports along the Arabian Sea within range of a growing and increasingly accurate Iranian ballistic missile inventory. Amir Ali Hajizadeh, commander of the Iran’s Islamic Revolutionary Guard Corps (IRGC) Aerospace Force, stated as recently as 2019 that “[e]verybody should know that all American bases and their vessels in a distance of up to two thousand kilometers are within the range of our missiles.”5 As the U.S. largely located its bases to support operations before or after the 1991 conflict with Iraq, it would be helpful to consider establishing new infrastructure that is less vulnerable to Iranian missiles and drones and provides for a more efficient, layered defense. Our regional partners would welcome the initiative and could significantly defray costs.
The U.S. has acquired substantial operational experience in combatting regional threats. At the same time, however, many of America’s allies are constrained by political instability, economic problems, internal security threats, and mushrooming transnational threats. Although the region’s overall score remains “moderate” as it was last year, it is in danger of falling to “poor” because of political instability and growing bilateral tensions with allies over the security implications of the proposed nuclear agreement with Iran and how best to fight the Islamic State.
With this in mind, we score the Middle East region as “moderate” relative to the ability of U.S. forces to operate in defense of America’s national interests.
Asia. The Asian strategic environment is extremely expansive. It includes half the globe and is characterized by a variety of political relationships among states that possess widely varying capabilities. The region includes 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 the People’s Republic of China and North Korea.
American conceptions of the region must therefore recognize the physical limitations imposed by the tyranny of distance. Moving forces within the region (to say nothing of moving them 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, means that the United States, unlike Europe, cannot necessarily count on support from all of its regional allies in responding to any given contingency.
The militaries of Japan and the Republic of Korea are larger and more capable than European militaries, and both countries have a sustained interest in developing missile defense capabilities that will be essential in combatting the regional threat posed by North Korea. In Japan, the public continues to express awareness of and more interest in the need to adopt a more “normal” posture militarily in response to China’s increasingly aggressive actions; this indicates a break with the pacifist tradition that has characterized the Japanese since the end of World War II.
We continue to assess the Asia region 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 difficulty that would be involved in projecting U.S. military power and sustaining combat operations in each one. As a whole, the global operating environment maintains a score of “favorable,” which means that the United States should be able to project military power anywhere in the world to defend its interests without substantial opposition or high levels of risk other than those imposed by a capable enemy.
Threats to U.S. Interests
America faces challenges to its security at home and interests abroad from countries and organizations that have:
- Interests that conflict with those of the United States;
- Hostile intentions toward the U.S.; and
- In some cases, growing military capabilities that are leveraged to impose an adversary’s will by coercion or intimidation of neighboring countries, thereby creating regional instabilities.
The government of the United States constantly faces the challenge of employing the right mix of diplomatic, economic, public information, intelligence, and military capabilities to protect and advance its interests. Because this Index focuses on the military component of national power, its assessment of threats is correspondingly an assessment of the military or physical threat posed by each entity addressed in this section. Admittedly, military power undergirds or backstops other elements of national power, but economic or diplomatic efforts cannot defeat an armored division or a missile barrage: When other instruments fail, military power is the only means by which to defeat physical attacks that threaten core U.S. interests.
China presents the United States with its most comprehensive and daunting national security challenge across all three areas of vital American national interests: the homeland; regional war (including potential attacks on overseas U.S. bases as well as against allies and partners); and international common spaces. China is challenging the U.S. and its allies at sea, in the air, and in cyberspace. It has sparked deadly confrontations on its border with India and poses a standing and escalating threat to Taiwan.
The Chinese military can no longer be viewed as a distant competitor. China has begun to field indigenous aircraft carriers and advanced missile technology. It is rapidly expanding its nuclear arsenal and conducting live-fire exercises and mock blockades around Taiwan. If current trends persist, the gap between the Chinese and U.S. militaries will likely narrow further, and the idea that China might surpass U.S. capabilities in some fields will seem far less implausible.6
This Index assesses the overall threat from China, considering the range of contingencies, as “aggressive” for level of provocative behavior and “formidable” for level of capability.
Although Russia has the military capability to harm and (in the case of its nuclear arsenal) to pose an existential threat to the U.S., it has not yet conclusively demonstrated the intent to do so. Nevertheless, especially in view of its war against Ukraine, Russia remains a significant threat to America’s interests and allies in the European region.
Russia may not be the threat to U.S. global interests that the Soviet Union was during the Cold War, but it does pose challenges to a range of America’s interests and those of its allies. It continues its efforts to undermine the NATO alliance and presents an existential threat to U.S. allies in Eastern Europe. It also still maintains the world’s largest nuclear arsenal, and although a strike on the U.S. is highly unlikely, the latent potential for such a strike still gives these weapons enough strategic value vis-à-vis America’s NATO allies and interests in Europe to ensure their continued relevance.
In addition, although Russia has expended much of its arsenal of munitions and has suffered significant losses in its war against Ukraine, the decision by several countries to continue trading with Russia despite sanctions placed on the country has provided a steady flow of funds into Russia’s accounts that Putin can use to support his aggression. Russia therefore remains a significant security concern for the U.S., its NATO partners, and other allies.
For these reasons, the Index continues to assess the threat from Russia as “hostile” for level of provocative behavior and “formidable” for level of capability.
Iran represents by far the most significant security challenge to the United States, its allies, and its interests in the greater Middle East. Its open hostility to the United States and Israel, sponsorship of terrorist groups, and history of threatening the commons underscore the problem. Today, Iran’s provocations are mostly a concern for the region and America’s allies, friends, and assets there. Iran relies heavily on irregular (to include political) warfare against others in the region, and the number of ballistic missiles fielded by Iran is greater than the number fielded by any of its neighboring countries. The development of its ballistic missiles and threshold nuclear capability also make Iran a significant long-term threat to the security of the U.S. homeland.7
This Index therefore assesses the overall threat from Iran, considering the range of contingencies, as “aggressive” for level of provocative behavior. Iran’s capability score holds at “gathering.”
North Korea’s nuclear and missile forces represent its greatest military threat to the United States. Its naval and air forces would not be expected to last long in a conflict with South Korea and the U.S., but they would have to be accounted for in any defense by South Korea. Pyongyang’s ground forces are largely equipped with older weapons, but they also are extensive and forward-deployed. Thousands of artillery systems deployed near the demilitarized zone could inflict devastating damage on South Korea, especially Seoul, before allied forces could attrite them.
Greater North Korean nuclear capabilities could undermine the effectiveness of existing allied military plans and exacerbate growing allied concerns about Washington’s willingness to risk nuclear attack to defend its allies. A more survivable nuclear force could lead North Korea to conclude that it has immunity from any international response and therefore act even more belligerently and use nuclear threats to coerce Seoul into accepting regime demands. The regime could use threats of nuclear attack to force Tokyo to deny U.S. forces access to Japanese bases, ports, and airfields during a Korean conflict. Pyongyang might also assume that conditions for military action had become favorable if it believed that the U.S. extended deterrence guarantee had been undermined.
The increasing rate and diversity of North Korea’s missile launches shows that Pyongyang is making significant progress toward implementing a more capable and flexible nuclear strategy, including preemptive strikes with strategic, tactical, and battlefield nuclear weapons. During a crisis, the threshold for the use of nuclear weapons could therefore be breached more easily.
This Index assesses the overall threat from North Korea, considering the range of contingencies, as “testing” for level of provocative behavior and “gathering” for level of capability.
A broad array of terrorist groups remain the most explicitly hostile in their rhetoric and intent (even though much less capable of causing serious harm to the U.S., directly, than major powers like China or Russia) of any of the threats to America examined in the Index. The primary terrorist groups of concern to the U.S. homeland and to Americans abroad are the Islamic State of Iraq and al-Sham (ISIS) and al-Qaeda.
ISIS has lost its so-called caliphate, but it remains a highly dangerous adversary that is capable of planning and executing attacks regionally and—at the very least—inspiring them in the West. It has transitioned from a quasi-state to an insurgency, relying on its affiliates to project strength far beyond its former Syrian and Iraqi strongholds. Meanwhile, despite sustained losses in leadership, al-Qaeda remains resilient. It has curried favor with other Sunnis in areas of strategic importance to it, has focused its resources on local conflicts, has occasionally controlled territory, and has deemphasized (but not eschewed) focus on the global jihad. This approach has been particularly noticeable since the Arab Spring.
Regardless of any short-term tactical considerations, both groups ultimately aspire to attack the U.S. homeland and U.S. interests abroad. The terrorist threat to the U.S. homeland from Afghanistan and Pakistan remains real and uncertain in a rapidly shifting landscape that is home to a wide variety of extremist and terrorist groups. On one hand, the capabilities of al-Qaeda, the terrorist group that is most directly focused on attacking the U.S. homeland, have been degraded in South Asia. On the other hand, the U.S. withdrawal from Afghanistan and the Taliban/Haqqani Network takeover of the country have generated significant uncertainty about Afghanistan’s future and the panoply of terrorist and extremist groups operating in that space, including the local branch of the Islamic State.
In its interim peace agreement with the U.S., the Taliban ostensibly committed to preventing Afghan soil from being used to launch attacks against the U.S. homeland, but experts remain skeptical of these commitments. For its part, Pakistan continues to harbor and support a vibrant ecosystem of terrorist groups within its borders.
This Index assesses the threat from ISIS, al-Qaeda, and their affiliated organizations as “aggressive” for level of provocative behavior and “capable” for level of capability.
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. This Index focuses on the more apparent sources of risk and those that appear to pose the greatest threat.
Compiling the assessments of these threat sources, the 2024 Index rates the overall global threat environment as “aggressive” for threat actor behavior and “formidable” for material ability to harm U.S. security interests. We have raised our rating of the aggregated material ability (capability) of adversaries to harm U.S. interests from the 2023 Index’s “gathering” for several reasons:
- Mounting concern over China’s dramatic expansion of its power projection abilities (especially its investment in nuclear weapons);
- Russia’s potentially desperate desire for victory in its war against Ukraine, especially if this drives Moscow to be more aggressive in other areas of military competition with the U.S. and Western allies;
- Iran’s unabated investments in its nuclear program, ballistic missile capabilities, and terrorist groups in the Middle East; and
- Further decline in America’s military condition. We do not attempt a net comparison of U.S. military capabilities with those of competitors, either singly or in combination, but we also cannot view changes in the threat environment without taking into consideration America’s ability to deal with rising threats. Were the U.S. military stronger, improvements in a competitor’s military might not be so worrisome, but it appears that changes in adversary portfolios are not being offset by commensurate changes in the U.S. military or the militaries of key allies.
This leads us to sustain our score for the aggregated global threat environment as “high” in the 2024 Index.
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 service by service as the clearest way to link military force size; modernization programs; unit readiness; and (in general terms) the functional combat power (land, sea, air, and space) that each service represents.
We treated America’s nuclear capability as a separate entity because of its unique characteristics and constituent elements, from the weapons themselves to the supporting infrastructure that is fundamentally different from the infrastructure that supports conventional capabilities. We address the status of missile defense and the context within which it operates in a similar manner. We do not offer metrics by which to measure the effectiveness or sufficiency of current missile defense capabilities, but in describing the challenges involved in defending against an enemy missile barrage capable of damaging the U.S., we trust the reader will come to obvious conclusions about the sufficiency and shortfalls of current capabilities. Finally, while not fully assessing cyber as we do the Army, Navy, Air Force, Marine Corps, and Space Force, we acknowledge the importance of new tools and organizations that have become essential to deterring hostile behavior and winning wars.
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, the U.S. nuclear enterprise, and ballistic missile defense capabilities is one of force degradation or stunting 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). The services have undertaken efforts to reorient from irregular warfare to large-scale combat against a peer adversary, but such shifts take time and even more resources.
Because of the rising costs of fuel, munitions, and repair parts, the lack of qualified maintainers and maintenance facilities, and the aggregate effects of the sustained use of forces and provision of munitions to Ukraine, as well as our limited industrial capacity, much of the progress in regaining readiness that had been made in 2020 and 2021 has been lost. The forecast for 2024 is likewise gloomy given a proposed FY 2024 defense budget that will not be sufficient to keep pace with ongoing and dramatic increases in inflation and an agreement to limit federal spending (to include defense accounts) that was arranged in FY 2023 to forestall defaulting on the national debt until January 2025.
Experience in warfare is ephemeral and context-sensitive. Valuable combat experience is lost as servicemembers who individually gained experience leave the force, and it retains direct relevance only for future operations of a similar type: Counterinsurgency and adviser support operations in Iraq, for example, are fundamentally different from major conventional operations against a state like Iran or China.
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 of the sort being seen in Ukraine and toward which the U.S. military services have only recently begun to redirect their training and planning. Additionally, the force is still aged and shrinking in its capacity for operations even if limited quantities of new equipment like the F-35 Lightning II fighter are 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 either 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 in direct comparison. Rather, they are assessments of the institutional, programmatic, and material health or viability of America’s hard military power, benchmarked against historical instances of use in large-scale, conventional operations and current assessments of force levels that would likely be needed to defend U.S. interests against major enemies in contemporary or near-future combat operations.
Our analysis concluded with these assessments:
- Army as “Marginal.” Based on the historical use of its ground forces in combat, the Army has less than two-thirds the forces it would need in its Active Component to handle more than one major regional conflict. This shortfall in capacity might be offset if the modernity or technological capability of its forces were very high, but this is not the case. Much of the Army’s primary equipment is old, and despite modest progress in modernization, nearly all new Army equipment programs remain in the development phase and in most cases are at least a year from being fielded. FY 2024 requested funding levels for procurement and research and development (R&D) are down 8 percent from the preceding year, which further slows the pace of Army equipping and reduces the speed of procurement to below industry’s minimum sustainment rates in some cases. With regard to readiness, the Army’s internal requirement is for “66 percent…of the active component BCTs [to be] at the highest readiness levels,” and it has exceeded this level in FY 2024.
- In short, although the Army has made progress in its readiness for action, it is still aging faster than it is modernizing and continues to shrink in size as it struggles to recruit young Americans to join the service—a situation that is proving extraordinarily hard to remedy. Consequently, the Army is scored as “marginal” overall.
- Navy as “Weak.” The Navy needs a battle force consisting of 400 manned ships to do what is expected of it today. Its current battle force fleet of 297 ships reflects a service that is much too small relative to its tasks. Given current and projected shortfalls in funding for shipbuilding, the Navy is unable to arrest and reverse the decline of its fleet as adversary forces grow in both number and capability. Compounding the shortfall in capacity, the Navy’s technological edge is narrowing relative to peer competitors China and Russia. Ships are aging faster than they are being replaced, with older ships placing a greater burden on the maintenance capabilities of our relatively few shipyards. In addition, the Navy’s inadequate maintenance infrastructure prevents ships in repair from returning to the fleet in a timely manner, and the loss of steaming days needed to train crews to levels of proficiency diminishes readiness. In combination, this leads to an overall score of “weak” for the U.S. Navy.
- Air Force as “Very Weak.” The Air Force has deployed an average of 28 fighter squadrons to major theaters of war since the end of World War II. This equates to 500 Active Component fighter aircraft to execute one major regional conflict (MRC). Adding a planning factor of 20 percent for spares and attrition reserves brings the number to 600 aircraft. An Air Force able to manage more than a single major conflict would necessarily require 1,200 active-duty, combat-coded fighter aircraft. Currently, the service has 897—three-quarters of the requirement as assessed by this Index. The service’s inventory of bombers is worse, standing at 64 percent.
- Accounting for better inventories in aerial refuelers and strategic lift aircraft, the USAF currently is at 83 percent of the capacity required to meet a two-MRC benchmark. However, the geographic disposition of these aircraft limits the ability of the service to deploy them rapidly to a crisis region, and its ability to replace combat losses is highly questionable because of low mission capability rates (a function of maintenance and trained crews). The result is an Air Force that probably is able to handle only a single major conflict, and that only by resorting to global sourcing, leaving it unable to do much else.
- New F-35 and KC-46 aircraft continue to roll off their respective production lines but in small numbers that are more than offset by aircraft retirements. Incredibly low sortie rates and flying hours across every pilot community will prevent any Air Force combat-coded fighter squadron from being able to execute all or even most of its wartime mission. At best, half of the cadre of pilots within the most capable units will be able to execute just “some” of the unit’s wartime missions. There is not a fighter squadron in the Air Force that holds the readiness levels, competence, and confidence levels required to square off against a peer competitor, and readiness continues to spiral downward.
- As with a three-legged stool, success or failure is determined by the weakest leg. The shortage of pilots and flying time for those pilots degrades the ability of the Air Force to generate the quality of combat air power that would be needed to meet wartime requirements even if aircraft production was higher and newer aircraft comprised a larger percentage of the Air Force. The overall score for the U.S. Air Force is therefore “very weak.”
- Marine Corps as “Strong.” The score for the Marine Corps was raised to “strong” from “marginal” in the 2022 Index and remains “strong” in the 2024 Index for two reasons: because the Corps’ capacity is measured against a one-war requirement rather than two (to which the other services are held) and because of the Corps’ extraordinary, sustained efforts to modernize (which improves capability) and enhance its readiness during the assessed year. Of the five services, the Marine Corps is the only one that has a compelling story for change, has a credible and practical plan for change, and is effectively implementing its plan to change. However, in the absence of additional funding in FY 2024, if the Corps retains its intention to reduce the number of its battalions from 22 to 21, this reduction will limit the extent to which it can conduct distributed operations as it envisions and replace combat losses (thus limiting its ability to sustain operations). The Corps is already at 73 percent of the battalions (and related air and logistical capabilities) it should have. It needs to grow.
- Though the service remains hampered by old equipment in some areas, it has nearly completed modernization of its entire aviation component, is making good progress in fielding a new amphibious combat vehicle, is fast-tracking the acquisition of new anti-ship and anti-air weapons, and is aggressively leveraging developments in unmanned systems and advanced computing and communication technologies. Full realization of its redesign plan will require the acquisition of a new class of amphibious ships, for which the Corps needs support from the Navy.
- The Corps is still too small and has no stated desire to grow, but it possesses fairly modern equipment, especially its air arm, and is wholly committed to adapting as rapidly as possible to meet the challenges of an evolving threat environment, thus prompting this Index to score it as “strong” overall.
- Space Force as “Marginal.” The number and type of Backbone and ISR assets are sufficient to support global PNT requirements and the majority of strategic-level communications, imagery, and collection requirements of the National Command Authorities and the Department of Defense. While that capacity is growing, the Space Force is not capable of meeting current—much less future—on-demand, operational, and tactical-level warfighter requirements. The service doubled its counterspace weapons systems with capabilities with the Ascent and Tetra-1 satellites, adding the first two known offensive systems to the Space Force Portfolio. Other counterspace systems are probably being developed or, like cyber, already in play without public announcement. Nevertheless, the USSF’s current visible capacity is not sufficient to support, fight, or weather a war with a peer competitor.
- The services’ asset modernization plan has significantly accelerated the delivery of systems to the force over the past year, significantly elevating USSF capabilities. However, a majority of Backbone and intelligence, surveillance, and reconnaissance (ISR) assets have exceeded their designed life spans, and a willingness to delay and/or defer the acquisition of replacement systems remains a Department of the Air Force legacy. The capability of these satellites is marginal, but the service has narrowed gaps in space situational awareness and in defensive and offensive capabilities.
- The mission sets, space assets, and personnel that transitioned to the Space Force and those that have been assigned to support the USSF from the other services have not missed an operational beat since the Space Force stood up in 2019. However, there is little evidence that the USSF has improved its readiness to provide nearly real-time support to operational and tactical levels of force operations or that it is ready to execute defensive and offensive counterspace operations to the degree envisioned by Congress when it authorized creation of the Space Force.
- Overall, the Space Force rates a grade of “marginal,” which is an improvement over its grade in the 2023 Index.
- Nuclear Capabilities as “Marginal.” The scoring for U.S. nuclear weapons must be considered in the context of a threat environment that is significantly more dangerous than it was in previous years. Until recently, U.S. nuclear forces needed to address one nuclear peer rather than two. Given a U.S. failure to adapt rapidly enough to these developments and the Biden Administration’s decision to cancel or delay various programs that affect the nuclear portfolio, this year’s Index changes the grade for overall U.S. nuclear weapons capability to “marginal.”
- U.S. nuclear forces face many risks that without the continued bipartisan commitment to a strong deterrent could warrant an eventual decline to an overall score of “weak” or “very weak.” The reliability of current U.S. delivery systems and warheads is at risk as they continue to age and threats continue to advance. The fragility of “just in time” replacement programs only exacerbates this risk. In fact, nearly all components of the nuclear enterprise are at a tipping point with respect to replacement or modernization and have no margin left for delays in schedule—delays that appear to be occurring despite the best efforts of the enterprise. Since every other military operation—and therefore overall national defense—relies on a strong nuclear deterrent, the United States cannot afford to fall short in fulfilling this imperative mission.
- Future assessments will need to consider plans to adjust America’s nuclear forces to account for the doubling of peer nuclear threats. It is clear that the change in threat warrants a reexamination of U.S. force posture and the adequacy of our current modernization plans.
- Therefore, the score for this portfolio has changed from “strong” to “marginal.” Failure to keep modernization programs on track while planning for a three-party nuclear peer dynamic could lead to a further decline in the strength of U.S. nuclear deterrence in future years.
In the aggregate, the United States’ military posture must be rated as “weak.” The Air Force is rated “very weak,” the Navy and Space Force are “weak,” and the U.S. Army and nuclear portfolio are “marginal.” The Marine Corps is “strong,” but the Corps is a one-war force, and its overall strength is therefore not sufficient to compensate for the shortfalls of its larger fellow services. With respect to nuclear capabilities, if the United States should need to deploy nuclear weapons, the escalation into nuclear conflict would seem to imply that handling such a crisis would challenge even a fully ready Joint Force at its current size and equipped with modern weapons. Additionally, the war in Ukraine, which threatens to destabilize not just Europe but the economic and political stability of other regions, shows that some actors (in this case Russia) will not necessarily be deterred from conventional action even though the U.S. maintains a strong nuclear capability,8 which is how this critical military capability was assessed in the 2023 Index; the decline of America’s nuclear portfolio to “marginal” makes this even more worrisome. Thus, strong conventional forces of necessary size are essential to America’s ability to respond to emergent crises in areas of special interest.
The 2024 Index concludes that the current U.S. military force is at significant risk of not being able to meet the demands of a single major regional conflict while also attending to various presence and engagement activities. The force would probably not be able to do more and is certainly ill-equipped to handle two nearly simultaneous MRCs—a situation that is made more difficult by the generally weak condition of key military allies.
In general, the military services continue to prioritize readiness and have seen some improvement over the past few years, but modernization programs, especially in shipbuilding and the production of fifth-generation combat aircraft, continue to suffer as resources are committed to preparing for the future, recovering from 20 years of operations, and offsetting the effects of inflation. In the case of the Air Force, some of its limited acquisition funds are being spent on aircraft of questionable utility in high-threat scenarios while R&D receives a larger share of funding than efforts meant to replace quite aged aircraft are receiving. As observed in the 2021 through 2023 editions of the Index, the services have normalized reductions in the size and number of military units, the forces remain well below the level needed to meet the two-MRC benchmark, and substantial difficulties in recruiting young Americans to join the military services are frustrating even modest proposals just to maintain service end strength.
Congress and the Administration took positive steps to stabilize funding in the latter years of the Budget Control Act of 2011 (BCA). This mitigated the worst effects of BCA-restricted funding, but sustained investment in rebuilding the force to ensure that America’s armed services are properly sized, equipped, trained, and ready to meet the missions they are called upon to fulfill will be critical. This is amplified by the extent to which the United States has drawn from its inventories of munitions and equipment to support Ukraine’s defense and the extent to which the defense industry has been limited in its ability to replenish depleted stocks, much less support the expansion and deepening of U.S. capabilities in preparation for any other conflict. At present, the Administration’s proposed FY 2024 defense budget falls far short of what the services need to regain readiness and replace aged equipment, and Congress’s intention to increase the proposed budget by approximately 3.5 percent over the FY 2023 budget9 accounts for barely half of the current rate of inflation, which averaged 8 percent in calendar year 2022 and 4.6 percent from January–July 2023.10
As currently postured, the U.S. military is at significant risk of not being able to defend America’s vital national interests with assurance. It is rated as “weak” relative to the force needed to defend national interests on a global stage against actual challenges in the world as it is rather than as we wish it were. This is the inevitable result of years of sustained use, underfunding, poorly defined priorities, wildly shifting security policies, exceedingly poor discipline in program execution, and a profound lack of seriousness across the national security establishment even as threats to U.S. interests have surged. In 2023, this has been compounded by the cost of U.S. support for Ukraine’s defense against Russia’s assault, which is further exacerbated by the limited willingness of allies in Europe to shoulder a greater share of the support burden. This was made worse by Hamas’s barbaric attack on Israel, which prompted the U.S. to provide equipment, munitions, and missile defense resources to Israel to aid in its defense, further pressuring America’s defense posture. These wars have laid bare the limited inventories of equipment, munitions, and supplies of all supporting countries as well as the limitations of the industrial base that will be required to replenish them, especially in the U.S., which must always look to its core national security interests.
Once again, future security threats cannot be predicted in their time, place, and severity, but they are nevertheless knowable with certainty because history has demonstrated repeatedly that threats arise with regularity in spite of efforts to deter and thwart them; that they often appear in complex arrangements of enemies, timing, and location; and that the time available to build capacity and readiness to deal with them is always in short supply. It is therefore incumbent on national leaders and the American people to approach investing in the nation’s security with the utmost seriousness and consistency. Otherwise, everything the United States is and represents is at substantial risk.
 See U.S. Department of Defense, 2022 National Defense Strategy of the United States of America Including the 2022 Nuclear Posture Review and the 2022 Missile Defense Review, pp. 4–6, https://media.defense.gov/2022/Oct/27/2003103845/-1/-1/1/2022-NATIONAL-DEFENSE-STRATEGY-NPR-MDR.PDF (accessed September 6, 2023). Though the Biden Administration’s defense budget requests have neither enabled the growth of U.S. military capabilities nor even arrested their decline, the text of the National Defense Strategy implies the need for a large military force capable of action in at least two distinct theaters against two very different opponents possessing substantial conventional and nuclear capabilities. For example, “The PRC seeks to undermine U.S. alliances and security partnerships in the Indo-Pacific region, and leverage its growing capabilities, including its economic influence and the People’s Liberation Army’s (PLA) growing strength and military footprint, to coerce its neighbors and threaten their interests…. ¶ In addition to expanding its conventional forces, the PLA is rapidly advancing and integrating its space, counterspace, cyber, electronic, and informational warfare capabilities to support its holistic approach to joint warfare. The PLA seeks to target the ability of the Joint Force to project power to defend vital U.S. interests and aid our Allies in a crisis or conflict. The PRC is also expanding the PLA’s global footprint and working to establish a more robust overseas and basing infrastructure to allow it to project military power at greater distances. In parallel, the PRC is accelerating the modernization and expansion of its nuclear capabilities. The United States and its Allies and partners will increasingly face the challenge of deterring two major powers with modern and diverse nuclear capabilities—the PRC and Russia—creating new stresses on strategic stability.” Ibid., p. 4. Additionally, Russia is described as an “acute threat.” Ibid., pp. 2 and 5. “Even as the PRC poses the Department’s pacing challenge, recent events underscore the acute threat posed by Russia. Contemptuous of its neighbors’ independence, Russia’s government seeks to use force to impose border changes and to reimpose an imperial sphere of influence. Its extensive track record of territorial aggression includes the escalation of its brutal, unprovoked war against Ukraine. Although its leaders’ political and military actions intended to fracture NATO have backfired dramatically, the goal remains. Russia presents serious, continuing risks in key areas. These include nuclear threats to the homeland and U.S. Allies and partners; long-range cruise missile threats; cyber and information operations; counterspace threats; chemical and biological weapons (CBW); undersea warfare; and extensive gray zone campaigns targeted against democracies in particular. Russia has incorporated these capabilities and methods into an overall strategy that, like the PRC’s, seeks to exploit advantages in geography and time backed by a mix of threats to the U.S. homeland and to our Allies and partners.” Ibid., p. 5. When the threats posed by Iran, North Korea, and violent extremist organizations as outlined in the NDS are added, one can only conclude that the U.S. military must be able to handle more than one major problem at a time—a necessity that successive Administrations have faced for several decades.
 According to some accounts, the U.S. has been involved in 106 wars or conflicts since its founding, but many analysts would dispute the idea that an intervention that is small in scale, scope, or duration or a set of drone strikes against an enemy is the same as a war that calls for large-scale mobilization and the use of substantial military power over a significant period of time. Even “large-scale” is a relative term: a function of the U.S. population and the resources available at that time. America’s war with Mexico in the 1840s pales in comparison to World War II, but for its time, it was a significant commitment of military forces. In the latter sense, the U.S. has been at war or involved in meaningful armed conflict approximately 15 times, not including its iterative clashes with North American Indian tribes from the late 1700s to the early 1920s. Accounting for the 12–13 larger wars, the average time between them is 16 years, skewed by the short periods of five years between World War II and Korea, seven years between Korea and Vietnam (at its earliest stage), and how one accounts for America’s invasion of Iraq in 2003 relative to operations in Afghanistan or its earlier war against Iraqi forces in 1991. Conflicts that fit into the category of “war” include the American Revolution, 1775–1783; Quasi-War with France, 1798–1800; War of 1812 (against Great Britain), 1812–1815; Mexican–American War, 1846–1848; U.S. Civil War, 1861–1865; War with Spain, 1898; Philippine–American War, 1899–1902; Mexican Border War, 1910–1919; World War I, 1917–1918; World War II, 1941–1945; Korean War, 1950–1953; Vietnam Conflict, 1960–1973; Gulf War (Operations Desert Shield and Desert Storm), 1990–1991; Operation Enduring Freedom (most directly associated with operations in Afghanistan), 2001–2021; and Operation Iraqi Freedom, 2003–2011.
 Various national security pundits have offered alternative approaches to dealing with a world that is increasingly at odds with U.S. interests, but whether the prescription is deterrence by denial, deterrence by punishment, integrated deterrence, or some other use of power to deter a competitor from acting against U.S. interests, the U.S. must possess the ability to deal with an imminent threat of substantial capabilities while also preserving the ability to handle a different threat of potentially similar magnitude. This requires capacity, capability, relevant proximity to potential use, and the ability to sustain military action over time in more than one area.
 Robert Greenway, “Strength in Unity: A Sustainable US-Led Regional Security Construct in the Middle East,” Hudson Institute, August 2023, p. 9, https://s3.amazonaws.com/media.hudson.org/Robert+Greenway+-+Strength+in+Unity+-+A+Sustainable+US-Led+Regional+Security+Construct+in+the+Middle+East.pdf (accessed October 26, 2023).
 Reuters, “Iran Says U.S. Bases and Aircraft Carriers Within Range of Its Missiles: Tasnim,” September 15, 2019, https://www.reuters.com/article/us-iran-usa-missiles-idUSKBN1W004A (accessed October 26, 2023).
 Peter Robertson and Wilson Beaver, “China’s Defense Budget Is Much Bigger Than It Looks,” Heritage Foundation Commentary, September 26, 2023, https://www.heritage.org/asia/commentary/chinas-defense-budget-much-bigger-it-looks.
 Greenway, “Strength in Unity: A Sustainable US-Led Regional Security Construct in the Middle East,” p. 10.
 In the formal sense, Ukraine is not covered by the United States’ “nuclear umbrella” per treaty or other legal obligation. Nevertheless, Russia is very aware of U.S. nuclear capabilities and of its interests in Europe’s stability and security, most clearly seen in U.S. obligations as a member of NATO but also in the trade, diplomatic, security, and cultural relations it has with European countries in general. That Russia chose to invade Ukraine in spite of the objections the U.S. was sure to raise and the deep concerns the U.S. and its European partners would surely have as a result of Russia’s naked aggression, can only mean that America’s nuclear posture was not, itself, a deterrent. Thus, the presence, capacity, and capability of U.S. conventional forces on the European continent must be considered on their own merit.
 At $842 billion, the defense budget for FY 2024 proposed by the White House is 3.2 percent higher than the $816 billion proposed for FY 2023. The $832 billion proposed by the Senate represents an increase of 2 percent (or 3.5 percent depending on one’s reference point for what constitutes defense spending). The proposal voted out of the House Appropriations Committee generally aligns with the Senate’s, but as this book was being prepared, it had not been subject to a vote of the full House. All of these numbers fall well below the current rate of inflation. See Chart, “DoD Topline Growth FY22–FY23–FY24 Budgets,” in U.S. Department of Defense, Office of the Under Secretary of Defense (Comptroller/Chief Financial Officer), United States Department of Defense Fiscal Year 2024 Budget Request, PowerPoint Presentation, March 2023, p. 3, https://comptroller.defense.gov/Portals/45/Documents/defbudget/FY2024/FY2024_Budget_Request.pdf (accessed August 22, 2023); news release, “Bill Summary: Defense Fiscal Year 2024 Appropriations Bill,” Committee on Appropriations, U.S. Senate, July 27, 2023, https://www.appropriations.senate.gov/news/majority/bill-summary-defense-fiscal-year-2024-appropriations-bill (accessed August 22, 2023); and press release, “Committee Approves FY24 Defense Bill,” Committee on Appropriations, U.S. House of Representatives, June 22, 2023, https://appropriations.house.gov/news/press-releases/committee-approves-fy24-defense-bill (accessed August 22, 2023).
 CoinNews Media Group LLC, U.S. Inflation Calculator, “Current US Inflation Rates: 2000–2023,” https://www.usinflationcalculator.com/inflation/current-inflation-rates/ (accessed August 22, 2023). Based on “U.S. Labor Department data published on Aug. 10, 2023.”