As trade tensions flared between the world’s largest economies, communication between the United States and China has been so shaky that the two superpowers cannot even agree on whether they are talking at all.

At a White House economic briefing this week, Treasury Secretary Scott Bessent demurred multiple times when pressed about President Trump’s recent claim that President Xi Jinping of China had called him. Although top economic officials might usually be aware of such high-level talks, Mr. Bessent insisted that he was not logging the president’s calls.

“I have a lot of jobs around the White House; running the switchboard isn’t one of them,” Mr. Bessent joked.

But the apparent silence between the United States and China is a serious matter for the global economy.

Markets are fixated on the mystery of whether back-channel discussions are taking place. Although the two countries have not severed all ties, it does seem that they have gone dark when it comes to conversations about tariffs.

“China and the U.S. have not held consultations or negotiations on the issue of tariffs,” Guo Jiakun, a spokesman for China’s foreign ministry, said at a news conference last Friday. “The United States should not confuse the public.”

However, China’s Commerce Ministry said this Friday that it was now considering holding talks with the Trump administration after repeated attempts by senior U.S. officials to start negotiations. White House and Treasury Department officials did not respond to requests for comment about whether such outreach had occurred.

The standoff over when and whether Washington and Beijing will hold economic talks comes as the Trump administration is scrambling to reach trade deals with dozens of countries that could soon face high tariffs. On April 2, Mr. Trump imposed what he calls “reciprocal” tariffs on countries that he believes have unfair trade and other economic barriers. Those levies, which sent global financial markets plunging, were paused for 90 days to give countries time to reach agreements with the United States.

China, which reached a largely unfulfilled trade pact with Mr. Trump during his first term, has indicated that it has little interest in talking about a new agreement until the United States rolls back what it views as a barrage of aggressive and unfair trade measures.

Mr. Trump increased tariffs on Chinese imports to a minimum of 145 percent last month, in a bid to force China into trade negotiations. Chinese officials responded by issuing their own tariffs on American products and clamping down on exports to the United States of minerals and magnets that are necessary for many industries.

The economic toll of the tit for tat is starting to become clear. The International Monetary Fund last month lowered its growth outlook for both countries and the world, warning that the tariffs had made a downturn more likely. Government data released this week showed Chinese factory activity slowing in April and first-quarter growth in the United States weakening.

During a cabinet meeting on Wednesday at the White House, Mr. Trump acknowledged that children in the United States may wind up with fewer dolls that cost more. But he insisted that he would continue to push for a “fair deal” with China, which he described as the “leading candidate for the chief ripper-offer.”

The Trump administration is focused on trade deals with about 18 of America’s most important trading partners that are subject to the reciprocal tariffs. Mr. Bessent indicated that talks with China would operate on a separate track from the other negotiations.

The Treasury secretary is expected to take the lead on the China negotiations while Howard Lutnick, the commerce secretary, oversees most of the other talks. However, Mr. Trump has not formally appointed or authorized a U.S. official to negotiate on his behalf with China, leaving Chinese officials to believe that the Trump administration is not ready or serious about trade talks.

Mr. Bessent, who had an introductory call with his Chinese counterpart in February, said that he held informal talks with Chinese officials over issues such as financial stability during the spring meetings of the International Monetary Fund and the World Bank last week. He said that they spoke about more “traditional things” but did not say that trade was discussed. The Treasury Department did not issue a summary of any meetings with Chinese officials.

In an interview with Fox News this week, Jamieson Greer, the United States trade representative, said that he met virtually for over an hour with his Chinese counterpart before April 2 but that there had been no talks since Mr. Trump announced his “Liberation Day” tariffs.

Mr. Trump has suggested that Mr. Xi should call him to begin the talks personally, noting their strong personal relationship. But that is not how China typically handles important economic matters. The United States and China traditionally work out their economic differences through a structured dialogue with formal meetings and working groups led by a top economic official from each country.

“This very personalistic approach by President Trump, who wants to negotiate directly with President Xi, doesn’t match with the Chinese system at all,” said Craig Allen, a fellow at the Asia Society Policy Institute’s Center for China Analysis. “In the Chinese system, these things are carefully negotiated in advance, they go up multiple channels and it is highly controlled and scripted, and when it gets to the leader stage it is highly choreographed.”

Mr. Allen, who until recently was the president of the U.S.-China Business Council, suggested that China was most likely mindful of the acrimonious meeting that Mr. Trump had with President Volodymyr Zelensky of Ukraine in February and that Mr. Xi would be wary of a situation that could lead to a public confrontation with Mr. Trump.

During the Biden administration, Treasury Department officials worked with China to create economic and financial working groups of midlevel staff members that were intended to prevent tensions over tariffs and export controls from spiraling out of control. Those lines of communication do not appear to be in use in the Trump administration, which tends to view them as a waste of time.

“That is exactly the kind of thing that these groups can help do — help make sure that the policy you deploy is well tailored to achieve the objective and communicates to the other side what you’re trying to achieve before it’s too late and you instead have to react to potentially unintended consequences or a message that was not intended to be transmitted,” said Brent Neiman, a University of Chicago professor who was the Treasury’s deputy under secretary for international finance during the Biden administration.

During Mr. Trump’s first term, the president initially assigned the Treasury secretary at the time, Steven T. Mnuchin, to lead trade delegations to China. He later appointed Robert E. Lighthizer, his trade representative, who was viewed as more hawkish, to oversee the talks.

Veterans of that trade war believe the current deadlock could be more protracted because the tariffs are higher and both sides believe they are winning. If U.S. growth continues to slow while prices start to rise, it could add to the urgency for Mr. Trump to get real talks with China going.

“I think at some point we have to give them a graceful off ramp,” said Wilbur Ross, who served as Mr. Trump’s commerce secretary during his first term. “Whether that is somebody from our side calling them first or whether it’s simply appointing who will be our main representative — it may be at some point we need to make a symbolic gesture.

Michael Pillsbury, a top China adviser to Mr. Trump during his first term, said Beijing was most likely waiting to see what the deals that the Trump administration reaches with other nations such as India and Japan look like before engaging directly.

“They don’t want to start the formal talks because they want to know the bottom line from others first,” said Mr. Pillsbury, who speaks to U.S. and Chinese officials.

He noted that the trade fight has become a major point of national pride for China and that it believes that Mr. Trump’s demands — which Beijing does not fully grasp — will soften as American markets gyrate and midterm elections in the United States draw closer.

“Delay is very much in their interest, and a speedy deal is very much in Trump’s interest,” Mr. Pillsbury said.