What does all this have to do with the coronavirus? As panic has swept through financial markets in the last two weeks, investors have begun seeking safety in cash — and above all in dollars. The American economy itself may look weak, but the dollar is still the most universally acceptable means of payment and store of value.

The pressure of the coronavirus crisis was such that on Thursday the Fed widened the swap network to include all 14 of the central banks it supported in 2008. The news had an immediate calming effect. Pressure on the exchange rates of Brazil and South Korea eased; the dollar has slipped back from the highs it touched earlier in the week. But as the pandemic’s impact on the world economy deepens, will the swap line system of 2008, with its echoes of the Cold War era, still do the job?

Three things have changed since 2008. First, dollars are being used on a new scale by new financial actors. Second, the balance of the world economy has further shifted from the European Union-United States-Japan axis toward emerging markets. And third, the politics of the world economy have become far more antagonistic. Let’s take each in turn.

In 2008, European megabanks were the problem. Today the pressure is on Japanese and Taiwanese life insurers, pension funds and postal banks, which have made huge purchases of American corporate bonds that are now collapsing in value because of the shutdown of global economic activity. These financial institutions are not umbilically connected to the swap lines in the way that banks in London or Paris were. As the Fed struggles to calm the markets, the last thing it needs is for these institutions to unload their portfolios of American assets.

Corporate borrowers — for example Pemex, Mexico’s state-backed oil company — are also under immense financial pressure, as are the suppliers of complex manufactured goods. They borrow short-term in dollars to pay for raw materials and components moving along their complex supply chains. As the dollar soars and interest rates tighten, they face acute financial difficulties, adding further pressure to the physical disruption of the shutdown.

As for the growing power of emerging markets, China leads the way. But the growth of economies like Indonesia, Malaysia, Thailand and Turkey has also been spectacular. Once a relatively marginal part of the world economy, the emerging economies are now key drivers of global growth. American investors, and indeed the world economy, have a deep interest in their prosperity.

Finally, there is the question of China. In 2008, China was already the main driver of global growth, so much so that some feared that it might cause a crippling global crisis by selling off its portfolio of U.S. Treasuries. That did not happen. Instead, China powered through the recession with a gigantic domestic stimulus package. Today, the country’s economy is larger than ever, as are its holdings of American assets. All told, the foreign debts of China’s businesses come to $1.3 trillion. As the global scramble for dollars begins and the American currency rises in value, those debts become less sustainable. That risks unleashing a chain reaction.