On the sidelines of the spring meetings of the International Monetary Fund and World Bank this week, Treasury Secretary Scott Bessent tried to convey an important message about the United States dollar.

Speaking to a crowd of global policymakers, regulators and investors, Mr. Bessent sought to allay fears that had ballooned in recent weeks about the dollar’s global standing and the country’s role as the safest haven during times of stress. He reiterated that the administration would continue to have a “strong-dollar policy” and affirmed that it would remain the currency that the rest of the world wanted to hold, even though it had weakened against most major currencies.

For participants at the event, Mr. Bessent’s comments were a needed salve after a bruising couple of weeks in financial markets as a result of President Trump’s trade war. Violent swings in stocks, coinciding with the weakening of the dollar as investors fled U.S. government bonds, had incited panic.

The fact that Mr. Bessent found it necessary to emphasize that message in front of such a big crowd underscored how precarious the situation had become since Mr. Trump returned to the White House less than 100 days ago. What now looms large are uncomfortable questions about what happens if the international community starts to lose faith in the dollar and other U.S. assets, something that economists warn would be costly for Americans.

“People are playing through scenarios that previously had been judged unthinkable, and they’re playing them through in a very serious kind of way in the spirit of contingency planning,” said Nathan Sheets, the chief economist at Citigroup and a Treasury official in the Obama administration.

“If the United States is going to pursue aggressive economic policies, it’s natural for the rest of the world to step back and say, ‘Well, do we want to buy U.S. assets as we have in the past?’”

‘New World Order’

At a similar gathering hosted by the I.M.F. and World Bank six months ago, attendees were preparing for an entirely different economic backdrop. Convening less than two weeks before the presidential election, they still had in their sights a rare soft landing in which the major central banks finished their fight against high inflation while managing to avoid a recession.

The tariffs Mr. Trump had been talking about on the campaign trail were top of mind, but for the most part, they were viewed as a negotiating tactic. Any turn toward protectionism was widely expected to push up the value of the dollar compared with other currencies. The rationale was that tariffs would lower demand for imported goods, since they would make them more expensive for American consumers, and over time result in fewer dollars being exchanged for foreign currencies.

But since Inauguration Day, the opposite has occurred. An index that tracks the dollar against a basket of major trading partners has fallen nearly 10 percent in the last three months. It now hovers near a three-year low. The sharpest slide came after Mr. Trump announced large tariffs on nearly all imports in April. While he temporarily reversed course, the dollar has yet to recoup its losses.

There are reasons not to read too much into its recent weakening. The U.S. economic outlook has fundamentally changed. Businesses are “frozen” by tariffs, Christopher J. Waller, a governor at the Federal Reserve, said this week as he warned about layoffs stemming from the uncertainty.

Economists have sharply scaled back their estimates for growth while raising their estimates for inflation, a combination that carries a whiff of stagflation. In that environment, it is not surprising that the dollar and other U.S. assets appear less appealing.

Dollar depreciation — even if extreme — also does not necessarily translate to a loss of stature in the global financial system. There have been previous big drops in the value of the dollar that have not incited a wholesale shift away from the currency’s primacy, said Jonas Goltermann, the deputy chief markets economist at Capital Economics.

But at this year’s spring meetings, there was a palpable sense that something more ominous could be taking place. Joyce Chang, JPMorgan’s chair of global research, noted a disconnect between domestic and international participants at the conference that the Wall Street bank hosted during the week of the meetings.

U.S.-based investors appeared less concerned about a structural shift away from the country’s assets and more focused on the ways in which Mr. Trump could course-correct on his economic policies. International investors were consumed by the prospects of a “regime change” in the financial system and a “new world order,” Ms. Chang said.

Mr. Trump had recently escalated his attacks on Jerome H. Powell, the Fed chair, fanning fears about how much the administration would encroach on the central bank’s independence. That longstanding separation from the White House is broadly seen as essential to the smooth functioning of the financial system.

“The dollar’s role in the system was not ordained from above,” said Mark Sobel, a former Treasury official who is the U.S. chairman of the Official Monetary and Financial Institutions Forum. “It’s a reflection of the properties of the United States.”

Those include a large economy that transacts with the world; the financial system’s deepest, most liquid capital markets; a credible central bank; and the rule of law.

“I do believe that Trump is doing permanent damage,” Mr. Sobel said.

Few Alternatives

It is hard to overstate the dominance of the dollar globally, meaning there are real limitations to how significantly private and public investors can diversify away from it, even if they want to.

Most trade is invoiced in dollars. It is the leading currency for international borrowing. Central banks also prefer to hold dollar assets more than anything else, and by a wide margin.

“Anybody who’s looking for diversification has to be realistic,” said Isabelle Mateos y Lago, the chief economist at BNP Paribas. “Reserve assets, by definition, have to be liquid.”

Alternatives do exist, but they are hobbled by their own weaknesses. China lacks open, deep and liquid capital markets, and its currency does not float freely, tarnishing its appeal globally. Top European leaders — including Christine Lagarde, the president of the European Central Bank — have talked more readily about bolstering the prominence of the euro, something that is considered more plausible now that countries like Germany are stepping up their spending. But the amount of available euro-denominated safe assets pales in comparison with that of U.S. capital markets.

Still, in the recent period of volatility, investors have found a number of places to take cover. The euro, Swiss franc and Japanese yen have been clear beneficiaries. Gold has rallied sharply, too.

“You don’t need to have the role of the dollar as a reserve asset go to zero,” said Ms. Mateos y Lago. “A multipolar system can totally work.”

Burden or Privilege?

When asked at Wednesday’s event, which was hosted by the Institute for International Finance, whether the dollar’s reserve currency status was a burden or a privilege, Mr. Bessent said: “I actually am not sure that anyone else wants it.”

But economists warn that Americans would be losing clear benefits if the government was too cavalier about the dollar’s shedding its special status.

The country’s exporters would reap rewards, as a weaker dollar would make their products more competitive. However, that advantage could come at the expense of reduced spending power for Americans abroad and higher borrowing costs at a time when the government has huge financing needs.

Despite the pain that Americans may have to bear, the global financial system would be far more “resilient” if other currencies shared the dollar’s global role over time, said Barry Eichengreen, an economist at the University of California, Berkeley. During times of stress, that would mean multiple sources of liquidity.

However, three months into Mr. Trump’s second term, Mr. Eichengreen warned that a “dire scenario is now on the table” — a sharp sell-off of dollar-denominated assets into cash.

“A chaotic rush out of the dollar would be a crisis,” he said. “All of a sudden, the world would not have the international liquidity that 21st-century globalization depends on.”