Even if the timing of the launches is a coincidence, they could serve to remind the United States that it needs China’s help to maintain pressure on the North and keep its nuclear program in check.

“I come bearing sincerity, and hope in the current special circumstances to hold a reasoned, frank exchange of views with the U.S. side,” Liu He, China’s chief negotiator in the trade talks said after arriving in Washington, according to Xinhua, China’s official news agency. “China believes that increasing tariffs won’t solve problems, won’t benefit China or the United States, and nor will it benefit the global economy.”

Still, a resolution of the trade war during this week’s talks seems challenging.

China had been willing to protect intellectual property and open its markets to American business, but the Trump administration wanted the agreement to specify that some of those changes be made in Chinese law. For China, any legislative change or policy reversal could be a very public — and potentially humbling — reminder that it gave ground under pressure.

“That would bring back painful memories of the days of national humiliation in our history,” said Wang Yong, the director of the Center for International Political Economy at Peking University. “China has made too many concessions.”

The blaring nature of the Trump administration’s broadsides has sharpened the dilemma that Mr. Xi faces in the negotiations.

“To have Trump doing it so publicly is obviously very, very difficult for Xi Jinping,” said Susan L. Shirk, a professor at the University of California, San Diego, who worked as a deputy assistant secretary of state responsible for China under President Bill Clinton. “It makes it much more difficult for him to make the compromises needed.”