The tensions between the two countries show no signs of easing. Top advisers to Robert Lighthizer, the United States trade representative, briefed Congress on Tuesday afternoon about the state of the trade talks with China and left staff with the sense that the negotiations were in disarray.

Congressional aides said after the briefing that they were not optimistic about the prospects of reaching a significant deal by March 2, the new date for proposed increases in United States tariffs on China. One aide said that the trade officials, Stephen P. Vaughn, the general counsel of the trade representative’s office, and Jeffrey D. Gerrish, Mr. Lighthizer’s deputy, suggested that the tariffs that the United States had imposed on China would not be rolled back even if an agreement was struck by the deadline. The officials were also unsure about how they would even enforce the concessions that they were pressing China to make.

“The Trump-induced whiplash on China has left more questions than answers,” said Rep. Lloyd Doggett, a Texas Democrat who serves on the House Ways and Means Committee. “One day, he’s ‘Tariff Man,’ and the next, it’s ‘Let’s Make a Deal.’ Congress must get answers from this administration on what success looks like.”

In a plenary hall at W.T.O. headquarters on the shores of Lake Geneva this week, the global stresses were on view. The talks were closed to the public, but the United States and other countries made texts of their speeches available.

Under Mr. Shea, who also serves as the American permanent representative to the W.T.O., the United States has expressed its views in unvarnished language that has shocked other diplomats at times but is very much in line with Mr. Trump’s view that America is getting a raw deal on global markets.

“For too long, the rules of global trade have been tilted against U.S. workers and businesses,” the United States government said in a report it submitted as part of the trade policy review.

Critics accuse the United States of trying to undermine rules of trade it largely wrote, creating a free-for-all that would undercut global growth.