Diplomatically, we’re not even doing the easy stuff, like broadcasting solidarity with other countries struggling with COVID-19 outbreaks or congratulating countries that appear to have broken the back of their epidemic. We don’t appear to have concern that poor countries with weak public-health systems might eventually bear the brunt of the pandemic. We seem only to resent Chinese philanthropists for sending medical supplies to us, rather than thanking them for providing much-needed assistance.

In addition to the systemic damage to America’s soft power, the president’s smug unilateralism has encouraged others to act just as selfishly. The European Commission is prohibiting export of coronavirus-related medicines and equipment to preserve them for EU use. India, where many of the world’s generic drugs are made, is prohibiting export both of medicines and of their constituent ingredients. Even the countries of Europe’s Schengen Area, which permits passport-free travel, are shutting their national borders in response to the pandemic. Rather than a coordinated international response that forestalls panic by sharing information and assistance, the United States has led a stampede to narrow national responses. And everyone in the world will be less safe for it.

The battle-weary architects of the post–World War II order understood that international cooperation is a way of creating strategic depth—which is to say, it increases the distance between the heart of a country and the external forces that might threaten it. Collaboration gives early warning of problems before they become exorbitantly dangerous and expensive to address. The American presidents who bolstered institutions such as NATO, the World Bank, and the World Health Organization understood that behaving in altruistic ways would create a reservoir of goodwill for when the United States needed to ask friends to help in hard times. That’s what people all over the world understood when they declared, after the 9/11 attacks, that “we are all Americans now.” But a cooperative international order creates more than a feeling of fellowship; it also allows national contributions to accumulate into resource levels that none of our nations could reach unilaterally. Cooperation is cost-effective, even if we wish others contributed more.

Aaron E. Carroll and Ashish Jha: This is how we beat the coronavirus

The Federal Reserve has just showed how international leadership is done, coordinating efforts with the Bank of Canada, the Bank of England, the Bank of Japan, the European Central Bank, and the Swiss National Bank to cut interest rates and establish swap lines that assure dollar liquidity. Fed Chairman Jerome Powell’s actions reassured markets to the extent that this was possible under current circumstances. But the Fed acts independently on its mandate; it didn’t need White House leadership.