President Trump went on the offensive against Apple on Friday, demanding that the company begin making iPhones in the United States or pay tariffs of at least 25 percent on iPhones made abroad.

The ultimatum is the latest in a decade-long push to get the technology giant to move its supply chain. When he first ran for president in 2016, Mr. Trump promised voters that he would “get Apple to start building their damn computers and things in this country instead of other countries.”

But instead of bringing its manufacturing home, Apple has shifted production from China to other countries across Asia, including India, Vietnam and Thailand. Almost nothing is made in America, and an estimated 80 percent of iPhones are still made in China.

Yes. Apple could make iPhones in the United States. But doing so would be expensive and difficult and force the company to more than double iPhone prices to $2,000 or more, said Wayne Lam, an analyst with TechInsights, a market research firm. Apple would have to buy new machines and rely on more automation than it uses in China because the U.S. population is so much smaller, Mr. Lam said.

“It is absurd,” he said. “In the short term, it’s not economically feasible.”

There would be some benefits to moving the supply chain, including reducing the environmental costs of shipping products from abroad, said Matthew Moore, who spent nine years as a manufacturing design manager at Apple. But the upsides would be trivial compared with the challenges that would have to be overcome.

Supply chain experts say shifting iPhone production to the United States in 2025 would be foolish. The iPhone is nearly 20 years old. Apple’s top executives have said people may not need an iPhone in 10 years because it could be replaced by a new device built for artificial intelligence. As a result, Apple would invest a lot of money that it wouldn’t be able to recoup, Mr. Lam said.

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