More important, the Trump administration has repeatedly dropped the ball on efforts that might have succeeded in prompting China to curb production, something that would have benefited not just the United States but also allies that are now threatening to retaliate by imposing tariffs on American goods and services.

Most experts agree that China is not moving fast enough to close steel mills and aluminum smelters that it no longer needs because its economy is growing more slowly as it has gotten much bigger. The country’s leaders fear that moving faster could hurt its economy, harm state-owned banks that have lent to the metal industries and create unrest among workers who lose their jobs. But experts like Eswar Prasad, an economics professor at Cornell University, say that the United States, the European Union and other countries could pressure China to move faster to address this problem, especially if they worked together.

Characteristically, the Trump administration has displayed none of the diplomatic and economic savvy required to get China to change its policies. On Jan. 12, 2017, the Obama administration filed a case with the World Trade Organization that accused China of unfairly subsidizing aluminum producers and thus driving down global prices for the metal. But Mr. Trump’s trade representative, Robert Lighthizer, has failed to ask the W.T.O. to convene a panel of judges to hear the case, effectively suspending it. Mr. Lighthizer’s office declined to answer questions about the case.

Perhaps Mr. Lighthizer, a trade lawyer who has represented the steel industry, did not believe the case would have been successful because he shares Mr. Trump’s contempt for the W.T.O., an organization the United States was instrumental in creating to help prevent trade wars. Last month, Mr. Trump said the organization “makes it almost impossible for us to do good business,” arguing that American officials get to pick too few judges on its dispute resolution panels. But these assertions are belied by the fact that the United States has won nearly 86 percent of the cases it has brought before the W.T.O. since 1995.

Another opportunity for addressing excess steel production came in talks last summer between Chinese officials and Mr. Trump’s commerce secretary, Wilbur Ross, and his Treasury secretary, Steven Mnuchin. The Chinese told the Americans they would be willing to reduce China’s steel production capacity by 150 million tons by 2022. But Mr. Trump rejected the offer. An unnamed administration official told The Financial Times that Mr. Trump wasn’t interested in striking a deal because he had already decided that he wanted to impose tariffs.