Almost 2,000 years ago, an overextended empire picked a new fight with an old rival. After Persian incursions in Syria, the Roman Empire launched a military expedition that quickly backfired. Although the Roman army managed to defeat the Persians near modern-day Baghdad, it returned to Rome with some sort of infectious disease, likely smallpox. The resulting Antonine Plague, also known as the Plague of Galen, would afflict the Roman Empire for more than 20 years, killing as many as one in five in the empire’s city of Alexandria alone. Smallpox was already endemic in Rome, but the attack on Persia surely made Rome’s myriad health problems even worse.

Unfortunately, our current leaders in the United States have not heeded this cautionary tale. With most of the country under coronavirus lockdown and the world economy crashing, one would think the Trump administration has enough to deal with already. However, tensions with Iran remain high and war is not out of the question. To make matters worse, segments of the administration remain fixated on sparking conflict with Iran. This is not just ill-advised for humanitarian reasons. Such rancor could boomerang back on the U.S. in potentially lethal ways — as the Romans discovered.

The U.S.-Iran relationship remains fraught, as tensions have relaxed only somewhat since the killing of General Qassem Soleimani at the start of this year. Recently, Iran has placed new missiles around the Persian Gulf, the U.S. has considered major military strikes, and like their Parthian predecessors, today’s Iranian military harries Western objectives in Syria. Both the U.S. and Iran remain uncomfortably close to the brink.

It is in this hostile context that the coronavirus has complicated matters. Regrettably, both sides have rejected cooperative moves that could ameliorate the pandemic. While Iran certainly shares some of the blame, rejecting American aid based on “an unfounded conspiracy theory” and the Trump administration’s “maximum pressure” sanctions campaign has endangered Iranians and Americans alike.

Such sanctions inflict undue suffering on the citizens of the target countries, but the logic of suspending a portion of them goes beyond altruistic Good Samaritanism. Coronavirus is a pandemic, meaning combatting its spread anywhere must be a matter of concern everywhere.

Decisions like the U.S. plan to block International Monetary Fund loans for Iran during this pandemic are short-sighted, because they mistakenly presume that curtailing the spread of coronavirus in Iran will not help stop its spread in the U.S. But exacerbating a pandemic in an adversary’s country doesn’t make one’s own country safer. To paraphrase a Republican president who actually handled an epidemic well, the more we help fight coronavirus over there, the less we’ll have to fight it over here. It should be obvious by now that this virus does not respect borders.

With elements in both governments still “yearning for a fight,” actions, including sanctions, which heighten the risk of military confrontation are foolhardy. Given the readiness problems the U.S. military is already facing due to coronavirus, now seems like exactly the wrong time to seek confrontation with an Iranian military likely riddled with the disease. Moreover, even if Trump administration hardliners succeed in militarily achieving the regime change they implicitly seek, the resulting instability would certainly accelerate the spread of coronavirus. As Philip H. Gordon of the Council on Foreign Relations and Ariane M. Tabatabai of Columbia University put it, “it is fair to ask whether the political and social collapse of a country of 80 million people at a time of a global pandemic is in the United States’ — or anybody’s — interest.” In other words, if Tehran collapses, the United States may encounter the same tainted success as the nominally victorious Romans in 166.

Why then have our leaders chosen so perilous a course? Narrow definitions of national security. Clearly, as others have recently pointed out, the U.S. is in need of a new national security approach, one that prioritizes the real and shared threats Americans face, including disease, climate change, and nuclear proliferation.

This approach would be well within the American foreign policy tradition. At the height of the Cold War, the U.S. and the Soviet Union worked together to combat infectious diseases like smallpox. President Kennedy opened his administration by challenging the United States to “a struggle against the common enemies of man: tyranny, poverty, disease, and war itself.” Such efforts culminated in landmark agreements like the nuclear Non-Proliferation Treaty and the Limited Test Ban Treaty. Indeed, President Obama worked with autocratic competitors in Beijing and Moscow to achieve the Paris Climate Accord and the Iran nuclear deal, while at the same time confronting them when other interests collided.

It is in that tradition that we must work together to combat a common threat. This virus, like the equally indiscriminate threats of climate change and weapons of mass destruction, is coming for us all. The national security apparatus, from its graduate schools to its most senior leaders, needs to reassess its definitions of national security. Realizing the dangers of even a militarily “successful” war with Iran is a good place to start. Just ask the Romans.

The author is the Roger L. Hale Fellow at Ploughshares Fund, which provides financial support to the Quincy Institute for Responsible Statecraft.