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.