Will your next iPhone cost $2,000? More? The answer to that question — and the future of America’s wealthiest company and our imperiled financial markets — rests on one man with a very tricky task.

Steve Jobs might have been the visionary who made touch-screen phones a reality, but it was the operational genius and savvy statesmanship of Tim Cook, his low-key successor, that sent Apple’s revenues and its stock price into the stratosphere. His triumph in fending off Donald Trump’s first-term threats was not without cost, however: By flattering Mr. Trump with attention while making little to no changes to Apple’s China ties, Mr. Cook played the president for the fool.

Now Mr. Trump is back in the White House, and he has slapped China with tariffs so high that they present a major threat to Apple’s hammerlock on the smartphone market. It’s clearly going to be harder for Mr. Cook to pull off the same trick. If he fails — and most bet he will — it could be a huge blow to his company, to the stock market and to our broader economy.

Let’s start with a sense of the stakes. Apple has largely been the world’s most valuable company since 2011, and until Mr. Trump’s tariff threats, it was worth around 8 percent of the entire S&P 500. If your retirement is invested in index funds, Apple is your single biggest investment. It’s so enormous that merely issuing a quarterly profit warning, as the company did in early 2019, rattled global financial markets.

Then let’s turn to the fact that moving production to the United States — the stated goal of Mr. Trump’s extreme tariff regime — is almost impossible for Apple. China is home to roughly 90 percent of Apple’s global production, and it’s the only country where Apple has made such extraordinary investments in people, machinery and processes over a quarter-century.

Analysts at the firm Wedbush estimated that a domestically built iPhone would cost more than triple its current price tag, which would mean about $3,500. Worse, America simply lacks the manufacturing expertise, the competitive industrial clusters and even the population density required to make Apple products en masse.