But China can play a strong defense. The country has broad latitude, under special rules it negotiated with the World Trade Organization, to maintain restrictions within its market.

“The problem is that U.S. trade negotiators agreed to provisions allowing China to limit market access for U.S. companies unless they engaged in joint ventures,” said Michael R. Wessel, a member of the U.S.-China Economic and Security Review Commission, which Congress created to monitor the relationship between the two countries.

“Potential Chinese partners demand the family jewels,” he said. “Companies can say no, but too many give in to Chinese pressure to make a quick buck.”

The current trade frictions trace back to the Clinton administration.

When China was entering the W.T.O. in 1999 and 2000, American negotiators gave Beijing some leeway, a position later supported by the administration of George W. Bush. As a developing country, China was allowed extra protections, such as requirements that companies in critical industries work with Chinese partners. China, in return, promised to shed the extra rules gradually as its economy matured.

But Beijing did not open up, even as China evolved into an economic powerhouse. Quite the opposite has happened under President Xi Jinping, who has pursued a more nationalistic agenda than his reform-minded predecessors.