Both sides left a window for negotiators to reach a deal before their economies are affected by higher tariffs, but the threat of a persistent trade war gave Wall Street its worst day in four months. The S&P 500 index fell more than 2.4 percent, and the tech-heavy Nasdaq dropped 3.4 percent. Global investors appeared calmer today: Asian markets dropped modestly, and European markets opened slightly higher.

Closer look: An escalation of Mr. Trump’s trade war is poised to hit every conceivable consumer product. The items that could face tariffs up to 25 percent include toys, shoes, coffee makers, smartphones, fireworks, guns and more.

The background: Senior officials from both countries have met 11 times since Mr. Trump took office. But significant differences remain over how tariffs should be rolled back and whether the negotiated provisions must be enshrined in Chinese law.

White House reviews Iran plan, in echoes of Iraq war

Defense officials have updated a military strategy that envisions sending as many as 120,000 U.S. troops to the Middle East if Iran were to attack or accelerate work on nuclear weapons.