FOR DECADES, global health has been a core part of American foreign policy. Through supporting the well-being of some of the world’s most vulnerable populations, it is clear that America embraces generosity through its role as an international superpower. However, these acts should not be solely regarded as magnanimous or altruistic. Grappling with the health of global populations has crucial benefits for American interests.

This reality is evidenced by three of the world’s deadliest epidemics—HIV/AIDS, tuberculosis (TB) and malaria. The U.S. government is the largest donor to global malaria-relief efforts and is among the largest donors for both antituberculosis and HIV/AIDS programs. Its bilateral efforts include the hugely efficacious President’s Emergency Plan for AIDS Relief (PEPFAR), the President’s Malaria Initiative (PMI) and the U.S. Agency for International Development’s (USAID) TB program. Additionally, powerful multistakeholder partnerships that the United States has propelled, such as the Global Fund, have catalyzed and complemented these bilateral programs. In sum, the United States has had a remarkable impact on disease control.

Before the United Nations established the Millennium Development Goals in 2000, HIV/AIDS, TB and malaria were rampantly destructive phenomena. In 1999, AIDS took the lives of 2.8 million people, and annual new infections were as high as 5.4 million. Now, because of U.S.-supported efforts, the annual number of new HIV infections has fallen by 34 percent and AIDS-related deaths have declined by 27 percent. Similarly, TB mortality rates have fallen more than 50 percent with an annual incidence-decline rate of 1.5 percent. Deaths from malaria have also been halved since 2000, largely through safe, insecticide-treated nets.

America’s role at the forefront of controlling these three diseases may appear as an act of global goodwill, but it also provides equally positive benefits for our nation. Disease knows no boundaries, and in a world of accelerating travel and migration, international health security has become a top priority to our own interests, prosperity and safety.

Additionally, not only does economic growth facilitate improved public health, but the reverse is true as well. Given a strong correlation between economies’ dynamism and populations’ health, investing in curbing the three diseases is beneficial to American economic interests while simultaneously improving our diplomatic relationships.

The United States has devoted billions of dollars to combating international disease. Washington is and always has been a leader in global health, providing one-third of funds pledged from governments to the Global Fund since its creation in 2002 in addition to bilateral programs on HIV/AIDS, TB and malaria. From 2002 through 2016, Global Fund–supported programs saved twenty-two million lives, helped eleven million people access antiretroviral therapy, tested and treated 17.4 million people for TB, and provided 795 million insecticide-treated bed nets to protect people from malaria. To reduce or slash funding now, when ending these epidemics is finally within reach, would have calamitous effects, squandering these investments as well as the sizable goodwill toward the United States they have elicited. Drug-resistant malaria and tuberculosis strains are becoming more prevalent, and many HIV-burdened nations are facing higher risks of outbreaks as youth populations, which are larger than preceding generations, reach adolescence and face greater risk of exposure. For the safety of our citizens and for the stability of the international community, it is in our best interests to continue, not abandon, efforts against these three diseases.

WHEN CONSIDERING the most plausible national-security threat, many Americans assume it is a nuclear attack or an act of terrorism. However, the global spread of an infectious disease is arguably the most likely catastrophic event that could result in the deaths of more than ten million people worldwide. The influenza epidemic of 1918 infected one-fifth of the world’s population and resulted in the deaths of an estimated fifty million people. The epidemic, which killed more people than any other infectious disease in history, generated more fatalities than all of the wars of the twentieth century combined.

This is not a danger to be dismissed as distant history. Quite the contrary. With advancements in travel technology and the increase of individuals crossing international borders, global health has indisputably emerged as a potent national-security issue. On an annual basis, eighty million individuals visit the United States, and in 2016 alone, seventy-seven million Americans took trips abroad. Additionally, global health security is not only a concern for our national population, but for American citizens living abroad—three hundred thousand of whom serve as military personnel and one million more in other public and private roles.

Security is no longer solely a matter of addressing substantial military threats or hostile political agendas. In 2000, the UN Security Council officially designated HIV/AIDS as a threat to international peace and security—the first time a disease had ever been characterized in such a way, and not merely as a public-health threat. The late Richard Holbrooke was right to push for that as U.S. ambassador to the UN. Uncontrolled spread of the HIV/AIDS pandemic had the potential to devastate economic growth and overwhelm weak or unaccountable governments’ capacity.

The military now recognizes the crucial role of public health in ensuring the safety of America. In 2016, the U.S. Department of Defense allocated $841 million for biodefense programs. These funds are used to address a myriad of global health concerns, such as biological weapons, disease surveillance and pandemic control, as was the case in the 2014 Ebola crisis, in which, for the first time, three thousand U.S. forces were deployed.

Our nation enjoys the luxury of advanced health systems and dependable disease-monitoring programs. Yet diseases abroad can and do pose direct risks to American safety. With the world experiencing vastly enlarged travel and migration patterns compared to even one or two decades ago, diseases are fast moving, pathogens may be weaponized, and the severe burden of disease can undercut the social, political, economic and military foundations of states and the stability of whole regions. Many states cannot unilaterally defend their populations from the spread of disease, which is why it’s in America’s own interest to regard global epidemics as not only a humanitarian problem, but a consequential matter of national security.

IT IS truly remarkable how far we have come in the fight against infectious diseases. This progress is especially apparent as it pertains to HIV/AIDS, tuberculosis and malaria. Millions of lives have been saved as the result of collaboration, innovation and resources channeled to accountable partnerships like the Global Fund. Since 2000, 7.8 million AIDS-related deaths have been averted, including 1.4 million children who have been spared HIV transmission from their mothers through testing and drugs. Currently, eighteen million people receive HIV treatment, 70 percent of individuals living with HIV know their status and 31.5 percent of young people have accurate basic knowledge about HIV transmission. Additionally, there has been significant progress made in TB—the most common co-infection for those who are HIV-positive. Between 2000 and 2016, fifty-three million lives were saved through TB diagnosis and treatment. Control and prevention have also made progress in antimalaria efforts; from 2010 to 2015, rates of new malaria cases fell by 21 percent.

Most strikingly, since 2000 the United States has led the collective action to address infectious diseases. In total, anti-AIDS efforts have collectively mobilized $187.7 billion through 2015. In 2016 alone, the United States devoted $6.6 billion in anti-AIDS efforts. Since 2001, America has directed $2.63 billion and $8.3 billion to tuberculosis and malaria programs, respectively. The United States has provided $13.2 billion to the Global Fund to grapple with all three diseases, propelling other donors to step up and match the United States two to one, given a canny legislated ceiling of 33 percent on the U.S. contribution. These investments, which have persisted for almost two decades, should not be thought of as mere charity. These billions of dollars—which come from hardworking taxpayers, private corporations and leading civil-society entities—serve as a major investment to avert a much larger cost to the United States and the world in lost lives, stability and economic growth.

Cutting back those strategic investments to fight international infectious diseases would inevitably result in future financial losses—primarily due to the rapid-spreading nature of diseases and their tendency to adapt to current treatments. If we retreat, larger sums of money will be needed to control the resurgence, rendering the billions of dollars originally disbursed a wasted investment. The costs per person of many pertinent treatments are modest. For example, an insecticide-treated net for malaria prevention costs on average $3. Furthermore, TB pills provided by the USAID TB program cost two cents each, and one antiretroviral pill for HIV/AIDS costs thirty cents. As such, a seemingly small reduction in funding can leave many people more vulnerable to disease.

Already, though, there are new challenges arising in countries carrying high HIV, TB and malaria burdens. While there have been notable strides made in TB reduction and prevention, it is still the eighth leading cause of death and the number-one deadliest communicable disease globally.

Furthermore, drug-resistant TB continues to be a growing problem. Multi-drug-resistant TB (MDR-TB) is contracted through a bacterium that is resistant to the two most powerful anti-TB drugs. In 2015, there were an estimated 480,000 MDR-TB cases. Furthermore, while still considered rare, extensively drug-resistant TB (XDR-TB) is resistant to at least four of the core anti-TB drugs, including the two most powerful. At least one case of XDR-TB has been reported in 117 countries. Drug resistant TB is more common in countries with weak TB programs that do not provide proper antibiotic-use instructions or do not have enough antibiotics to provide patients with a full treatment. Similarly, malaria resistance to the primary drug artemisinin is a newly emerging problem, detected in five countries so far.

For HIV, the growing demographic “youth bulge” will also result in lost investments if funds are not sustained. As of now, 43 percent of sub-Saharan Africa’s population is below the age of fourteen. While millions of children in this region have been born HIV-free thanks to anti-HIV initiatives, the epidemic will return in full force once the youthful population reaches adolescence if HIV-prevention programs are not adequately sustained, given empirically established patterns of somewhat older men transmitting HIV to younger women.

Absent the U.S. leadership to date that has spurred significant burden sharing, the threat of infectious diseases will only grow and further weigh down health systems and economies. While the United States has been at the vanguard against global infectious diseases through PEPFAR, PMI, the USAID TB program and financing organizations like the Global Fund, U.S. funding has plateaued in recent years. From 2006 to 2010, the United States’ global health funding practically doubled from $5.3 billion to $10 billion. However, since 2010 the amount contributed by the United States for global health funding has remained stagnant. While the House and Senate appropriations committees in July and September of 2017 rebuffed Trump administration proposals to cut contributions to the Global Fund and PEPFAR each by some 17–18 percent, even steady funding is not to be taken for granted.

While we have made admirable progress in reducing three massive killers over some fifteen years, investments are still much needed until epidemiological control is established. Given marked progress and strategic programs, ending these diseases as epidemics is within reach. Indeed, by addressing funding gaps, targeting hard-to-reach populations stricken with disease and ramping up prevention, progress could be accelerated. U.S. leadership could encourage even more domestic financing in countries with a high disease burden. Taking a page from the early George W. Bush administration, international financial institutions could provide targeted debt relief. That way, relieved countries could free up resources to address the epidemics. Innovative private finance should be increased.

Conversely, a retreat in investment would devalue the huge outlays to date, and produce human and economic costs that will plague the United States and world down the road. Let’s not stop a Marshall Plan for global health halfway to the finish line.

INVESTING IN the health of developing nations has been shown to encourage economic growth through reducing long-term health expenditures, increasing education and improving population productivity. Illness and poverty are often intertwined, as those who are burdened with disease face barriers to sustaining a job, and those who are impoverished lack the resources or access to services to support their health. Poor health and disease have global economic implications: in 2003, international business felt the repercussions for the severe acute respiratory syndrome (SARS) epidemic, which is estimated to have cost the world more than $30 billion in just a few months. Furthermore, the 2009 H1N1 outbreak cost Mexico’s economy $2.2 billion because of the economic disruption.

The presence of disease in a country impacts its economy because of its direct influence on the resilience of a nation’s workforce. Even short of mortality, malaria can be severely detrimental to a population’s productivity. By causing anemia, the disease can deplete working adults’ energy levels and cause loss of work days for enterprises. For children, malaria incidence can have cognitive developmental impact, further inhibiting their long-term ability to maximize their contribution to society—to apply their capabilities and thrive. With the highest incidence rates among individuals between the ages of fifteen and forty-nine, the majority of the working population, HIV can markedly inhibit one’s ability to work, absent antiretroviral therapy (ART). Children orphaned by AIDS also face the risk of losing necessary care and education, which can leave them ill-prepared to enter the workforce.

Research has repeatedly indicated that healthier populations stimulate the economy by living longer and saving more money. On an individual level, healthier people are economically more productive through their ability to work more efficiently, pursue education and spend personal income on goods as opposed to health-care costs. In poor countries, a 40 percent increase in life expectancy is correlated to a 1.4 percent increase in GDP per capita. The United States serves as an obvious example for this phenomenon, for it has been estimated that the increase in life expectancy from 1970 to 2000 alone contributed to an additional $3.2 trillion to the national economy.

Even addressing the burdens of one disease can have positive economic impacts. From 1965 to 1990, before there were more deliberate commitments to global health, a 10 percent reduction of malaria in endemic areas was associated with 0.3 percent higher economic growth.

Supporting global health helps to suppress epidemics and foster more resilient workforces—creating more opportunities for American businesses to invest and form meaningful international partnerships. Take, for instance, sub-Saharan Africa. From the perspective of an American interest, including that of the U.S.-headquartered business community, this is the region that has the greatest economic potential and highest rates of growth in the world. Fighting disease there has been an investment in serving that growth and interest. Supporting the health of struggling populations on a global scale has the potential to open valuable doors for economic opportunity and prosperity.

WHEN PROPOSING the PEPFAR program in his 2003 State of the Union address, then president George W. Bush stated, “Seldom has history offered a greater opportunity to do so much for so many.” By providing 11.5 million people with art, preventing HIV transmission to two million babies, and supporting HIV testing and counseling for 74.3 million people, PEPFAR has indeed achieved good for many. Global health aid serves to reinforce America’s role as a generous and humane guarantor of world order and has demonstrably built our soft power—global influence to persuade as well as militarily coerce.

Global health investments can benefit us as a nation by improving the United States’ standing among the leaders and populations of nations of strategic consequence. In the launch, conduct and outcomes of wars in Afghanistan and Iraq, President Bush’s presidency faced many points of heated criticism. Near the end of his presidency, a 2008 Pew Global Attitudes Project survey in twenty-four major countries around the world found that of the twenty-one outside sub-Saharan Africa, only in four (Britain, Poland, South Korea and India) did more than 50 percent of the population have a favorable view of the United States. In contrast, PEPFAR recipient countries reflected a different view. During the Bush administration, PEPFAR nations had a 68 percent approval rating of the United States, compared to the 46 percent global approval rating. This was particularly the case in sub-Saharan Africa. Among the positive developments that have coincided with this goodwill is the creation of the U.S. military’s African Command (AFRICOM) and success in eliciting African nations’ burden sharing in supplying their troops for multilateral peacekeeping missions.

In this regard, vital U.S. interests on the African continent—vis-à-vis China as a rapidly growing regional influence—point to further implications of global health policy. African nations hold vast economic potential. This is especially true in the sectors of agriculture, natural resources, energy production and infrastructure development. African maritime zones alone make up a total of thirteen million square kilometers, many of which are largely undeveloped with regard to infrastructure and resource exploration. Most of all, potential economic development on the continent would be deeply beneficial to the people of Africa. Yet it represents opportunities for the rest of the world too: less tapped and saturated economies for labor, along with resources and sales, hold the greatest lure—to the United States as well as to China.

The Chinese government has sensed Africa’s growing importance—especially as China’s own booming economy has an immense demand for the absorption of natural resources, from energy to minerals. The country has taken aggressive steps to ensure its stake in the continent’s potential. In 2003, Chinese investments and aid to Africa only totaled $70 million. Most recently, Beijing has promised a $60 billion loan and aid package to all the African countries combined. Along with this increase in assistance is a rise in economic interaction: Africa’s exports to China increased sixtyfold from 1998 to 2010 compared to the fivefold increase to the United States. If Washington keeps advancing health—specifically, a path to epidemiological control of HIV, TB and malaria in sub-Saharan Africa—it maintains an important form of influence on the continent. In the Trump era—even if it were to pursue the sort of business and infrastructure investments that China is making—the United States would lose an advantage in the battle for economic, diplomatic and strategic influence in Africa by decelerating its well-known investment in health.

Additionally, global health aid serves American interests as an underappreciated tool among the many efforts contributing to the diffusion of conflict and instability in partner nations. For instance, in PEPFAR countries, violence and political instability between 2004 and 2013 were reduced by 40 percent in contrast to 3 percent in non-PEPFAR countries. Furthermore, rule-of-law ratings also rose by 31 percent in PEPFAR countries during this time period versus only 7 percent in non-PEPFAR countries. U.S. programs focused on addressing particularly disruptive health phenomena facilitate peace, pluralism and prosperity consequential to our national interests.

The Trump administration and House Republicans have proposed a hard-power focus. However, it is important to diversify our toolbox in advancing U.S. influence abroad, rather than solely doubling down on the military instrument at the expense of other valuable means. Robert Gates, secretary of defense under both George W. Bush and Barack Obama, has observed:

“We must focus our energies beyond the guns and steel of the military, beyond just our brave soldiers, sailors, Marines, and airmen. . . . [B]ased on my experience serving seven presidents, as a former director of CIA and now as secretary of defense, I am here to make the case for strengthening our capacity to use ‘soft’ power and for better integrating it with ‘hard’ power.”

Disproportionately relying on military power and investments leaves chips on the table unused. Supporting global health security and development advances American interests and influence as well, and should as such be prioritized.

INVESTING IN global health is not solely an avenue to reinforce the virtuous identity of our nation, but generates tangible positive returns. Such returns include the safety of American citizens at home and abroad—as the highly dynamic nature of infectious diseases necessitates. With such investments, we can strengthen our relationships with economic, diplomatic and strategic partners while simultaneously contributing to sustainable productivity for those countries and our own.

Managing epidemics requires the United States to sustain efficacious bilateral programs such as PEPFAR, PM and USAID’s TB program. Backing collective instruments such as the Global Fund—which is responsible for supporting 47 percent of HIV treatment, 65 percent of malaria treatment and 84 percent of TB detection and treatment worldwide—is smart foreign policy. Whereas intergovernmental organizations like the United Nations and World Bank have had a mixed track record at best, by design and in practice the Global Fund has been accountable, inclusive of civil-society voices, and able to mobilize companies and foundations’ resources and know-how. It has also evolved and innovated where needed. Since 2015, assessments of multilateral aid agencies promulgated by the governments of United Kingdom, Australia and the Netherlands, and two reputable nongovernmental watchdogs—the Multilateral Organization Performance Assessment Network and PublishWhatYouFund—have given the Global Fund high marks. Its purpose, impact and model (where the UN, or some partnerships that are triumphs of form over substance, fall down) are precisely what the United States should advance.

In regard to infectious diseases, global prosperity and security are only as strong as their weakest links. Warfare and violence on the one hand, and flimsy, corrupt or brutal governments on the other, are not the only weak links affecting our vital interests. Without proper surveillance, prevention measures and treatment programs, disease outbreaks will cross international borders. Without U.S. leadership on global health, we squander past investments that have demonstrated through hard numbers their big impact, economic value and opportunities to reap the single, most successful area of “soft power” influence in the last two decades. The stakes are anything but low.

Mark P. Lagon is chief policy officer of the Friends of the Global Fight Against AIDS, Tuberculosis and Malaria, and distinguished senior scholar at the Walsh School of Foreign Service at Georgetown University. He served as ambassador-at-large to Combat Trafficking in Persons at the Department of State, 2007–09. He thanks Sydney Spencer of George Washington University for her research contribution to this essay.