The global pandemic is about to profoundly change the U.S. military’s role in defending the United States — even if Pentagon leaders don’t know it yet. As we noted in our last column, many Americans will look at the immeasurable damage wrought by the pandemic and conclude that defending the homeland from catastrophic threats is far more urgent than defending against foreign threats far from American shores. That fundamental shift is rapidly ushering in a new era for the Department of Defense, which will upend some of its bedrock assumptions about when, where, and how the U.S. military contributes to national security.

The Department of Defense has been operating under a broad national security strategy that has remained remarkably unchanged since the end of World War II. The United States has maintained a large standing military that has been forward deployed around the world to prevent direct attacks on the United States and to secure the global commons. Though the Trump administration has challenged some parts of this strategy (especially its emphasis on global allies and partners), the most recent versions of the National Security Strategy and the National Defense Strategy nevertheless reaffirmed most of its core principles.

Yet the pandemic has now suddenly and vividly demonstrated that a large, forward deployed military cannot effectively protect Americans from nontraditional threats to their personal security and the American way of life. In a deeply interconnected world, geography matters far less, and the security afforded by America’s far-flung military forces has been entirely irrelevant in this disastrous crisis. The number of Americans killed by the virus is about to exceed the number of U.S. troops killed in Vietnam, unemployment is higher than it has been since the Great Depression, and the social and human toll is simply incalculable. The ultimate damage will be so great that after the pandemic, the urgent need to defend the American people from devastating threats inside the homeland will quickly displace foreign threats atop the hierarchy of national security concerns.

The inevitable national security reckoning after the pandemic will pose tremendous challenges for the Department of Defense. Since the vast majority of its efforts and its enormous budget focus on deterring and defending against external threats as far away from the homeland as possible, it will need to adapt to a deeply changed environment where serious threats inside the homeland matter far more to most Americans. There are at least five key changes that will shape the choices and decisions that lie ahead for Pentagon leaders: cyber and space will be higher priorities than land, sea, and air; reliance on forward presence will diminish; the reserve component will become much more important; legacy programs and end strength will be cut — by a lot; and the prestige of the U.S. military will be dimmed.

Cyber and Space Will Be Higher Priorities Than Land, Sea, and Air

The U.S. military currently recognizes five warfighting domains: land, sea, air, cyber, and space. After the pandemic, external threats to the United States from the land, sea, and air will become much lower national security priorities than protecting against threats to the homeland from newly emerging and unconventional dangers. For the Department of Defense, that means a much greater emphasis on the cyber and space domains. Protecting the United States from a large-scale cyber attack on the nation’s critical infrastructure will become an extremely high priority, since it could harm the American people, economy, heath care system, and way of life at least as much (if not more than) COVID-19 already has. As horrible as this crisis is, food, water, power, and basic medical care are still largely available throughout the country and enabled by a fully functioning internet. A concerted cyber attack could upend distribution networks, disrupt power supplies and online access, and wreak havoc on a vast range of essential services from banking to telecommunications. Helping to defend the nation against this will almost certainly require the Pentagon to significantly expand the Cyber Mission Force. In particular, many more Cyber Protection Teams will be needed, and their mission should expand beyond their primary focus on .mil networks so they can provide much greater support to civil authorities and the private sector when requested. The newly created Space Force will also need to invest significant amounts of time and effort to protect U.S. civilian as well as military space assets, since they undergird every aspect of modern American life and are therefore tempting targets as well.

Reliance on Forward Defense Will Diminish

Forward defense has long been the cornerstone of U.S. defense strategy, but it will become less important as the focus grows on countering catastrophic threats against the homeland. In a post-pandemic world characterized by huge deficits, massive debt, and economic recession, the United States will continue to defend its most vital interests overseas: keeping NATO alive, protecting Eastern Europe from Russia, supporting Israel, and deterring conflict in Asia. But U.S. forces across the Middle East, Afghanistan, Africa, and even in some parts of the Pacific are likely to be drawn down if not withdrawn completely.

The economic crisis may also require changes to U.S. force posture in the places where military forces remain, since the sprawling network of overseas bases remains expensive. The United States spends about $10 billion a year to operate these bases, a figure that would be far higher without the very substantial amount of host nation support (which includes cash payments as well as various forms of in-kind support). Yet the global recession and rising debt levels spawned by the pandemic may make it harder for allies and partners hosting U.S. troops to continue providing such high levels of support. And here at home, the economic crisis will make members of Congress even more likely to support shuttering overseas bases in order to forestall any discussion of domestic base closures, since preserving jobs in their districts becomes even more critical at a time of such staggering unemployment levels.

The Reserve Component Will Become Much More Important

The increasing primacy of homeland defense means that the reserve component of the U.S. military may become equally if not more important to the nation than the active component, which would completely invert the traditional relationship between them. The vast majority of the military capabilities that have been used to respond to the pandemic, and that will be needed for future homeland crises, reside in the reserve component (which includes the National Guard and the reserve forces of the individual military services). The National Guard has been an especially valuable Swiss Army knife for governors and presidents, taking on a wide range of missions that have included ensuring public safety, moving critical supplies, and augmenting medical capabilities. The reserves also contain a disproportionate amount of support capabilities (such as engineering and medical units), which provide indispensable augmentation for civil authorities during domestic crises as well as reinforcements for large combat operations. By contrast, the warfighting units that comprise most of the active component have been largely irrelevant in this crisis. The active component has provided some field hospitals, and the (mostly civilian) U.S. Army Corps of Engineers has constructed some important health care facilities, but these contributions nevertheless remain quite limited. And, unlike the active component, the reserve component simultaneously provides critical capabilities for both homeland crisis response and overseas military missions, which provides a vital hedge against foreign conventional threats.

Legacy Programs and End Strength Will Be Cut — By a Lot

As we’ve argued, the massive economic crisis and growing political pressures for greater domestic spending mean that the defense budget will likely plummet — and may even make the sequestration-era cuts look rosy by comparison. The combination of sharply declining budgets, less emphasis on the land, sea, and air domains, and diminishing forward presence means that expensive conventional platforms like aircraft carriers, amphibious ships, and manned fighters will likely face severe cuts. Major legacy modernization programs that were already reaching unaffordable levels (like the F-35 fighter and the Ford-class aircraft carrier) will inevitably have to be significantly scaled back, and some may be canceled outright.

The services must also accept that major cuts to end strength are inevitable, and that they will probably fall heavily on the active component. The average cost of compensating an active servicemember has grown by 64 percent during the past two decades (adjusted for inflation), and active forces require substantial training and other readiness investments so they can respond rapidly to international crises. Because personnel are so expensive, budget cuts always force down end strength numbers, as happened during the first years of sequestration. But this time around, there will also be a lot of pressure to maintain, or possibly even to increase, reserve component end strength instead of spreading the cuts evenly between the two components. The reserve component offers a tremendous amount of bang for the defense buck. It provides essential capabilities for both domestic and international crises, and it is cheaper to maintain since its personnel serve on a part-time basis and are called up only when needed. As shrinking defense budgets force tough tradeoffs, the nation may have to rely more heavily on its reserve component to preserve important warfighting and homeland defense capabilities.