When the United States accidentally bombed China’s embassy in Belgrade, Serbia, in 1999, the deaths of three Chinese citizens personalized the episode and triggered a wave of anger and indignation against the United States. The chill to Sino-American relations lasted for months, even though the Chinese leader at the time, President Jiang Zemin, had previously taken a friendlier approach with the United States than Mr. Xi.

The Huawei executive, Meng Wanzhou, was arrested in Canada on Dec. 1 at the behest of American authorities, who claimed she deceived financial institutions and caused them to violate sanctions against Iran. Huawei has said it is unaware of any wrongdoing on her part.

“If Ms. Meng is extradited to America, then it will be difficult for the government to control the public’s anger — then the government will have to be tougher on Canada and the United States,” Mr. Tu said.

Mr. Trump and his top trade advisers were pleased by the tenor of his dinner with Mr. Xi in Buenos Aires. The Chinese leader was deeply engaged in the conversation, eager to convince the Americans that he was willing to go further in accommodating their grievances than any of his predecessors.

Along with the agreement in Buenos Aires, China’s leaders are also preparing a series of moves to open up the economy to more trade and foreign investment, an overhaul timed to the 40th anniversary later this month of the country’s initial post-Mao economic reforms. Such moves, like further tariff reductions, would provide Mr. Xi an opportunity to introduce market-friendly measures without seeming to give in to American pressure.

It’s unclear what will satisfy the administration — and more important, Mr. Trump.

Mr. Mnuchin has pushed for an agreement that obtains some concessions quickly, in order to reduce the potential economic fallout of an intensified trade war. Mr. Trump, concerned about the volatility in the stock markets, wants to get a big deal done, while also avoiding anything drastic that would damage his relationship with Mr. Xi, according to several officials with direct knowledge.