China’s problems in the area of technology could get worse. American officials are investigating whether a much bigger Chinese tech company, Huawei Technologies, also flouted American trade controls. Huawei has said it adheres to international conventions and local laws.

Despite that vulnerability, China has plenty of negotiating strengths.

White House trade officials have more expertise with trade law, but China has a small but cohesive team of negotiators who report directly to Liu He, a vice premier and nearly lifelong friend of Xi Jinping, the country’s top leader. The group has also streamlined Beijing’s ability to make economic policy decisions, a benefit in evaluating the impact of any concessions to the United States. Policy decisions that once took a month can now take as little as a day, said a person with a detailed knowledge of the process who insisted on anonymity because of the political sensitivity of the issue.

By contrast, the United States has shifted its demands and struggled to send out a consistent message.

The internal divisions were on display again on Sunday. Mr. Mnuchin said in the morning that any tariffs were on hold. Later that day, Robert E. Lighthizer, the United States trade representative, issued a statement in which he said, “As this process continues, the United States may use all of its legal tools to protect our technology through tariffs, investment restrictions and export regulations.”

In March and early April, Mr. Trump and his trade advisers threatened to impose tariffs unless Beijing agreed to curb long-term subsidies for high-tech industries.

The president then shifted to conciliation.

His financial policy advisers, led by Mr. Mnuchin, sought a fixed reduction of up to $200 billion in the $375 billion American trade deficit with Beijing. China’s trade negotiators resisted again, and the administration ended the weekend with a joint statement by officials from the two countries that did not commit China to any specific concessions.

Chinese and American officials did exchange lists last week of extra goods that China might buy to narrow the deficit. But China only committed to continue buying ever-rising quantities of American food and fossil fuels, a position reflected in the joint communiqué issued at the close of the talks.