A Better Way to Defend America

The United States is now engaged in an intense dialogue about the future of its relations with its European and Asian allies. This debate has been emotional, in part because it has been cast as a morality tale. On the one hand, advocates of U.S. President Donald Trump’s “America first” agenda argue that allies have not been grateful for U.S. backing and do not deserve the protection of the United States. They believe these states do not do enough to defend themselves and may not even share American values. On the other hand, those who defend the existing alliance structure argue that the United States must be faithful to its commitments and stand by the heroic people of Ukraine and Europe against a revanchist Russia.

But the United States did not shape the global military posture that it has maintained since World War II around a morality tale. The strategy of containment that remains the basis of current U.S. posture was based on an assessment of how the United States could protect what it valued most. A better way to approach the current debate is to ask whether the assessment that led to that strategy is as valid today as it was 75 years ago. The empirical answer to that question is no. What the United States should do in response can be debated, but its actions should be based on reality.

In the 1950s, when the existing alliance system was established, the distribution of economic power in the world meant that the United States had a major stake in the defense of Europe and Japan. Washington had to deploy its forces on the periphery of its Eurasian adversaries to deter attacks on its allies and defend them if war occurred. A defense posture is not a strategy or a foreign policy, but it is the basis of military capabilities, and it does create binding commitments. This force posture and its associated commitments made sense during the Cold War because of the economic value of Europe and Japan to the United States and the ability of the United States to deploy its forces safely nearer to enemy forces.

But the world has changed significantly since the Cold War. Although the U.S. share of global GDP is roughly the same as it was in 1990—26 percent, as measured by current exchange rates, or 17 percent using purchasing power parity exchange rates—Europe and Japan’s combined share of global GDP has declined by 50 percent. Moreover, because of the proliferation of short-range drones and long-range precision-strike cruise and ballistic missiles, it is now much more difficult for the United States to defend bases that are close to American adversaries against nonnuclear attacks. Finally, the current threats to the United States are not limited to attacks using nuclear and conventional intercontinental weapons. They also include unconventional warfare using cyber, drone, chemical, and biological weapons, as well as clandestine methods such as sabotage of critical infrastructure and threats to key personnel.

These changes in the global distribution of economic power and military technology do not mean that U.S. allies are irrelevant. Nor do they mean that the United States should give up its global military role. But they do mean that the United States needs to change the kinds of forces at its disposal and how it deploys and operates them, both to better defend the territory of the United States and for Washington to be able to exercise military power abroad as it judges necessary. Specifically, the United States will have to operate more of its forces from the Western Hemisphere and in space, and it needs to be able to better defend those forces. From bases primarily in the United States and in space, U.S. forces can retain global reach to operate against enemies in Asia and Europe. Experience shows that it has been impossible to predict where the United States will need to fight, so a reasonable approach is to build long-range forces that can pivot to wherever they are needed. The United States should also build forces that can be quickly deployed close to adversaries and survive attacks.

This new hemispheric posture will enable the United States to fully defend itself against emerging threats and maintain coercive dominance relative to its adversaries while allowing U.S. forces to strike at targets globally. Transitioning to this posture would necessarily be gradual and may require building relations with new partners such as Finland and Sweden and rebuilding relations with old partners such as Japan and the Philippines. But the defense of the United States will need to rest on forces based in the United States and in earth orbit.

THE NEW ECONOMICS OF POWER

Since the mid-twentieth century, a fundamental assumption of U.S. defense strategists has been that Eurasia contained multiple centers of industrial power. In 1947, the American diplomat George Kennan explicitly argued that there were five centers of industrial power in the world: the United States, the United Kingdom, western Europe, the Soviet Union, and Japan. Estimates of western Europe’s share of world GDP in the 1920s and 1930s, in the world in which Kennan began his career, are of course rough, but it was about 30 percent. According to this logic, a Eurasian enemy who captured one of the other centers of industrial power would endanger the United States. So Europe and Japan were naturally the central focus of U.S. defense posture after World War II.

But the economic importance of Europe has diminished. In 1988, a study by Andrew Marshall and Charles Wolf on the “future security environment”—an assessment of present and emerging geopolitical trends shaping defense priorities—observed that the European Community accounted for about 25 percent of global GDP and projected this share to decline only slightly, to about 22 percent, by 2010. Similarly, the study predicted that the Japanese share of global GDP, which was about 13 percent in 1988, would remain constant out to 2010. The study estimated that Europe’s and Japan’s combined share of global GDP would remain roughly constant at around one-third of world GDP. 

Reality, however, has diverged from those projections. Figures from the International Monetary Fund confirm that—using purchasing power parity currency conversion rates, as the study did—the EU share, as of 2024, has declined to 14 percent of world GDP, far less than the 22 percent the study predicted for 2010. Japan did even worse. Japan’s economy surged in the late 1980s and early 1990s, with its share of world GDP rising rapidly and peaking at about 14 percent in the mid-1990s. But since then it has steadily fallen, to the point that it accounted for just three percent in 2024.

In other words, since the end of the Cold War, the relative economic power of two of the traditional five centers of industrial power, Europe and Japan, has fallen from about 34 percent to 17 percent, a decline of about 50 percent. If the share of world GDP is measured using current currency conversion rates, that drop is even sharper, but since national security is primarily purchased from domestic sources with domestic inputs, purchasing power parity currency conversion provides a better assessment. By contrast, in the 34 years since the end of the Cold War, the United States’ share of global economic power has roughly held steady, and China’s has risen by a factor of ten, from 1.8 percent to 18 or 19 percent.

Trends in productivity growth suggest that the gap between the Japanese and EU economies on the one hand and the U.S. economy on the other will continue to grow. In the five decades between 1950 and 2000, the economies of France, Germany, Japan, and the United Kingdom steadily narrowed the U.S. advantage in output per hour worked. From 2000 to 2019, however, Japan’s productivity went flat, as did the United Kingdom’s, whereas the United States’ advantage in productivity relative to Germany’s remained constant. In the following five years, from 2019 to 2024, Japan continued to show zero productivity growth, and the U.S. advantage in productivity relative to the EU continued to widen. A 2024 report for the European Central Bank found that over that five-year period, hourly labor productivity in market services in the United States increased by more than 12 percent, whereas in the eurozone it increased by less than four percent.

What about the future distribution of economic growth? There is broad consensus that artificial intelligence is likely to be the new general-purpose technology that transforms economies around the world. In his 2024 book, Technology and the Rise of Great Powers: How Diffusion Shapes Economic Competition, the political scientist Jeffrey Ding presents data that suggests that the number and quality of AI engineers will be crucial to the coming AI-driven Fourth Industrial Revolution, and it uses an index that ranks universities worldwide for the number and quality of their AI resources. Thirty-two U.S. and Canadian universities, and seven Chinese universities, are in the top 50. By contrast, only one university in the United Kingdom and three in the EU make the list, and none in Japan do. Hence, the already observable declines in European and Japanese shares of world GDP are not likely to be reversed by the current revolution in data analysis.

THE PRECISION-STRIKE PROBLEM

Even as Japan and the countries of Europe have declined as economic powers, the difficulty of providing for their military defense has increased. The 1988 study also investigated the emergence of military power based on digital information technology, which gave rise in the 1980s and 1990s to precision-strike weapons. These weapons have made it possible to hit fixed and many mobile targets with great accuracy, regardless of the distance from which they are launched. U.S. military forces stationed on fixed bases on the periphery of China and Russia—the defense model that has been used since the early years of the Cold War—are now vulnerable to nonnuclear long- and shorter-range precision strikes. 

There is general agreement among defense strategists on what needs to be done to make these forces less vulnerable: fixed bases must be increased in number and the available forces dispersed among them. They must be concealed and mobile; or they must be put underground and defended with antimissile systems such as Patriot and Aegis Ashore that the United States has been transferring to Israel, Poland, and Ukraine. Strategists also agree that these mobile, dispersed, defended, and disguised forces should be deployed in what is called “complex terrain”—urban areas or jungle or mountainous regions, where they can be hidden more easily.

The problem is that all these approaches entail significant resources and, more important, require access to land, often in densely populated areas. At the same time, the United States faces the costs of modernizing all three legs of its nuclear triad, defending critical U.S. infrastructure against conventional and unconventional attacks, and protecting U.S. forces in space. This means building satellites that can detect impending attacks and maneuver away from them and that can defend themselves or avoid detection by being stealthy. It also means protecting ground stations that link to and support the networks of satellites. These are not optional tasks: without secure nuclear deterrence, secure bases in the United States, and secure capabilities in space, the U.S. military cannot operate at all. And given its fiscal pressures, the United States will not be able to pay for both these core defense needs and the costly steps required to defend its current forces in Europe and Asia.

Faced with this security dilemma, Washington does have an alternative. It can operate the bulk of its forces from bases in the United States and the Western Hemisphere. The logic here is straightforward: it is harder for China and Russia to strike at targets in the United States—and easier for the United States to defend against them—than at targets on those countries’ own peripheries. The longer a weapon has to travel, the more fuel it needs and the larger it must be; the larger it is, the easier it is to detect and attack. Stealth can reduce the visibility of large platforms, but stealth is expensive.

STRONG SHIELD, SWIFT SWORD

Although it is easier for a global power to maintain defense closer to home than to defend bases abroad, it is still difficult and expensive. Nor is such a homeland strategy adequate by itself. A comprehensive hemispheric shield must also be accompanied by a sword that can be swiftly and responsively wielded globally from defended bases at home. In fact, such a strategy was already envisioned in the early years of the Cold War.

In 1953, U.S. President Dwight Eisenhower introduced the New Look security policy, which set out to defend the country from Strategic Air Command bases in the Western Hemisphere. According to the concept, the United States would rely on a combination of strategic offensive nuclear forces based inside the country and dense continental air defenses based in the United States and Canada, which could protect against adversaries’ bombers, as well as antisubmarine warfare forces, to defend against submarines carrying missiles. As the official history of the Office of the Secretary of Defense puts it, “The new-style containment would depend primarily on offensive retaliatory power, chiefly strategic nuclear weapons plus continental defense.” Notably, in this approach, known as massive retaliation, other forms of defense, including conventional ground forces, would play a secondary role.

At the time, however, the strategy proved infeasible. In 1955, the cost of effective antibomber defenses was estimated at $40 billion over five years, or about 11 percent of U.S. GDP. The secretary of the treasury found the cost projections “incredible.” But the excessive price tag was mainly the result of technological limitations of that era. Thus, the most expensive components of the air defenses were not the radars or the weapons but the information system that would have been required to operate them, a capability that, in the era of vacuum tube computers, would have involved exorbitant costs.

Today, those costs have been dramatically reduced by Moore’s Law, even as the information systems themselves have exponentially increased in power. Enhanced missile defenses for the United States could involve expansion of the ground-based missile defense installation at Fort Greely, Alaska. In the 1970s, ballistic missile interceptors were also based in Montana and North Dakota. The expansion of bases in those locations should be reviewed, taking into account political constraints on land use. The possibility that adversaries could launch shorter-range ballistic and cruise missiles from submarines at targets in Alaska, Hawaii, and other Pacific and Atlantic coast states, means that defenses against theater-range ballistic missile and cruise missile defenses, such as the Aegis air defense system based on ships deployed off the coasts of the United States, would also have to be considered. These defenses could also be complemented by so-called passive defenses—steps such as more widely dispersing military assets or concealing and burying them—which raise the difficulty of launching an attack. In order to deter unconventional attacks, including cyberwarfare and sabotage operations, by China and Russia, a hemispheric defense strategy will also require much stronger internal security infrastructure.

The United States must deny adversaries positions in the Western Hemisphere.

Finally, the United States will need to maintain naval and air forces in the Western Hemisphere to enforce a new kind of Monroe Doctrine. A crucial part of this presence will be to prevent adversaries from establishing military positions in the Western Hemisphere from which the United States could be attacked with theater-range weapons, and destroy any such forces that are clandestinely inserted. The areas to be denied to possible adversaries include Canada, Greenland, Iceland, Mexico, Central America, northern South America, and the Caribbean islands and littoral areas.

Active and passive defenses are useful but have their limits. By enhancing its ability to launch global offensive strikes, the United States can reduce the damage that a potential attacker can inflict and deter attacks in the first place. Precision strike capabilities mean that now, unlike at the time of Eisenhower’s massive retaliation policy, nonnuclear offensive strike forces based in the United States can carry out effective attacks, even against faraway adversaries. And those attacks can be modulated both in terms of the targets they attack and the levels of destruction they inflict.

To strike effectively at targets, the United States must be able to detect, identify, locate, and—if the targets are moving—track them. Satellites in low-earth orbit are surprisingly close to targets on earth, since they are typically in orbits 150 to 300 miles in space, the distance from Boston to Philadelphia or from Kyiv to Kharkiv. Advances in precision timing make it possible to combine the data from many small sensors to produce information as accurate as one big sensor. Compared with NASA’s space shuttle, SpaceX’s partially reusable two-stage rocket, Falcon 9, has reduced the cost of putting a satellite into orbit by a factor of 20. If successful, SpaceX’s Starship spacecraft, which is now undergoing test launches, could reduce that cost by another factor of 20 or more. So intelligence, surveillance, and reconnaissance, or ISR, that previously could be done affordably only with airplanes and radars that operated close to enemies can now be undertaken from networks of satellites launched from the United States.

With high quality, survivable ISR, the United States will be able to find and designate targets almost anywhere. And with intercontinental range, stealthy, recoverable platforms that can carry many weapons, it will be able to strike them in a sustained nonnuclear campaign anywhere in the world from defended bases inside the country. Currently, that would mean using B-2 and B-21 bombers and cruise-missile-carrying nuclear submarines.

CORE STRENGTH

To be truly effective for the coming decades, any shift in the U.S. defense posture will have to be undertaken carefully and flexibly. Although some countries outside the Western Hemisphere matter less because their relative economic power has declined, some may matter more because of their location. Countries that are close to potential targets in the territory of a U.S. adversary and that have large amounts of complex terrain with low population densities may offer particular advantages to the United States. Deployed in such places, shorter-range offensive mobile weapons can better escape detection and destruction. Smaller weapons will also be lighter and easier to hide. Operating from countries comparatively close to potential targets, the United States can use smaller drones to provide useful ISR.

Washington may wish to work with allies that are close to U.S. adversaries and that have territories with these characteristics. In the case of Russia, this means that rather than abandoning NATO, the United States should reshape its relations with select NATO countries, such as Finland and other Nordic and Baltic states. On the periphery of China, the Philippine archipelago—which is close to the island of Hainan and serves as the base of the Chinese southern fleet—is another such area. The U.S. Marine Corps is already working with the Philippine government to explore the defensive use of these islands. Kyushu, the southernmost island in the Japanese home island chain, is also well located relative to the coast of the East China Sea and Chinese northern fleet bases. Hokkaido is well located relative to Vladivostok on the east coast of Russia. Access to these areas in times of war or crisis could be granted by the local governments; they could allow mobile U.S. forces with precision-strike weapons to deploy in return for military guarantees. In the longer term, autonomous offensive forces might be inserted by low observable aircraft or submarines and left behind with small or no human crews.

Ocean areas outside the Western Hemisphere include sea-lanes that adversaries use to import food, fossil fuels, and other critical goods. The United States might wish to be able to interdict this activity, which would involve a distant blockade. The challenge of imposing distant blockades is primarily one of information: there are thousands of ships transiting these sea-lanes every day, and no navy has enough ships to stop and search them all to find the ones of interest. Today, developments in space-based surveillance have gone a long way toward solving that problem.

Discussions of U.S. defense posture should begin by asking not who is virtuous but what does the world look like now and what will it look like in the future. Given the dramatic shifts in the global economy in recent decades, as well as the transformation of nonnuclear weapons capabilities and the rise of space-based sensors, it is clear that the defense posture that the United States established 75 years ago is no longer appropriate or adequate. The United States should look beyond its current disputes with its allies and ask how it can better situate its forces to protect core U.S. national interests in a more dangerous world.