Yet today, Argentina again finds itself in deep economic trouble. The peso has lost about half of its value against the dollar in the past year, with the depreciation accelerating in recent weeks. With foreign capital fleeing the country, forecasters in Argentina estimate that the economy will grow barely 1.5 percent this year, with inflation heading to 27 percent. The situation could threaten the country’s ability to make timely payments on its foreign debt. There is a sickening familiarity to the situation; it eerily resembles Argentina’s plight at the end of Ms. Fernández de Kirchner’s presidency and, indeed, similar episodes that have occurred at disturbingly frequent intervals throughout Argentina’s modern history.

To some extent, Mr. Macri has only himself to blame. Early in his administration, he reached a settlement with Argentina’s external creditors, whom his predecessor had ostentatiously stiffed, restored the integrity of official statistics and promised to institute permanent structural reforms. That enabled Argentina to refloat the economy with tens of billions of dollars in new borrowing. As of the end of last year, it appeared to be working: Mr. Macri’s coalition had won midterm elections and pushed needed pension reforms through Congress. Yet in too many areas, Mr. Macri yielded to his understandable desire to insulate the public against painful but necessary austerity. This left Argentina vulnerable to capital flight when the U.S. Federal Reserve raised interest rates.

Argentina now finds itself obliged to jack up its own central bank rate to 60 percent and tap a $50 billion line of credit with the International Monetary Fund, all of which is necessary to pay its bills and to restore confidence in private investors whose capital it needs. In other moves to raise short-term cash, the government has reinstated a tax on exports and put together a new package of budget cuts, abandoning the fiscal “gradualism” of earlier years. “The world decided that . . . we have to move faster,” Mr. Macri admitted.

Indeed, they do — and the political opposition will be quick to exploit the pain for ordinary Argentines. Fortunately, both the Trump administration and the IMF have signaled continued backing for Mr. Macri, who faces a re election campaign next year. Despite his mistakes, he is trying to rid Argentina at last of its populist addiction and the misguided policies it breeds. As long as he is willing to take political risks in this cause, his friends abroad must not abandon him.