President Trump’s long-promised trade war with China got going in earnest only last week, and he’s already botched it.

Mr. Trump and his sycophants brag about his deal-making artistry. So they are presumably familiar with some of the basic principles of business negotiations: Have a clear and attainable goal, know your adversary’s pain points (and don’t reveal your own), and make sure you don’t box them in so aggressively that they have no choice but to dig in their heels and retaliate.

Mr. Trump seems to have forgotten these things. His ill-conceived and amateurishly executed tariff war with China has now spiraled out of control, threatening world trade and badly damaging America’s global image. And it is far from certain that he will prevail.

Mr. Trump’s main problem is that he and his team evidently — and wrongly — assumed China was so desperate to protect its exports to the United States that it would simply bend to his will.

China exports more to the United States than to any other country — $438 billion worth in 2024. The staggering tariffs that Mr. Trump has imposed and that Beijing has matched in retaliation will hurt, coming at a time of weak Chinese consumer demand and investment and a struggling real estate market. But China is in some respects better prepared today to hold its ground than it was during Mr. Trump’s first term.