WASHINGTON >> Accusing Beijing of “reneging” on commitments it made in earlier talks, U.S. Trade Representative Robert Lighthizer said today that the Trump administration will increase its tariffs on $200 billion in Chinese goods early Friday, a sharp escalation in a yearlong trade dispute.

At the same time, a Chinese trade delegation is expected to arrive in Washington to resume negotiations on Thursday, a day later than originally planned.

Treasury Secretary Steven Mnuchin, who briefed reporters with Lighthizer, said that Trump officials learned over the weekend that Chinese officials “were trying to go back on some of the language” that had been negotiated in 10 earlier rounds of talks. Mnuchin and Lighthizer offered no details of China’s alleged backsliding, and there was no immediate response from Beijing.

The U.S. officials said that at 12:01 a.m. Eastern time Friday, the administration will raise tariffs on $200 billion in Chinese imports from 10% to 25%. President Donald Trump had announced plans to raise those tariffs via Twitter on Sunday, expressing frustration with the pace of negotiations. The reiteration today of the president’s threat from three high-level Trump officials reinforced the administration’s determination to throw Beijing on the defensive.

By threatening to raise taxes on Chinese imports, Trump is throwing down a challenge to Beijing: Agree to sweeping changes in China’s government-dominated economic model — or suffer the consequences.

The unexpected ultimatum shook up financial markets, which had expected the world’s two biggest economies to resolve a yearlong standoff over trade, perhaps by the end of the week.

“It’s a significant change in the president’s tone,” said Timothy Keeler, a partner at the law firm Mayer Brown and former chief of staff for the U.S. Trade Representative. “It certainly increases the possibility that you’ll have no deal.”

For weeks, Trump administration officials had been suggesting that the U.S. and Chinese negotiators were making steady progress.

Suddenly on Sunday, Trump said he had lost patience: “The Trade Deal with China continues, but too slowly, as they attempt to renegotiate. No!” he tweeted.

Trump also said he planned “shortly” to slap 25% tariffs on another $325 billion in Chinese products, covering everything China ships to the United States.

The two countries are engaged in high-stakes commercial combat over China’s aggressive push to establish Chinese companies as world leaders in cutting-edge fields such as robotics and electric vehicles.

The United States accuses Beijing of predatory practices, including hacking into U.S. companies’ computers to steal trade secrets, forcing foreign firms to hand over technology in exchange for access to the Chinese market and unfairly subsidizing Chinese firms at the expense of foreign competitors.

The Trump administration has imposed 10% tariffs on $200 billion in Chinese imports and 25% tariffs on another $50 billion. The Chinese have retaliated by targeting $110 billion in U.S. imports.

Global stock markets sank today on Trump’s tweetstorm. But shares in the United States regained some of the lost ground on news that Chinese officials were planning to go ahead with this week’s meetings in Washington. Still, the Chinese government did not provide details on exactly when talks would resume and who would be on China’s negotiating team.

U.S. officials said they expected that China’s delegation would led again by Vice Premier Liu He, a confidante of Chinese President Xi Jinping.

Beijing is wrestling with an internal conflict: It is eager to end a trade fight that has battered Chinese exporters, but it doesn’t want to look like it’s bowing to the Trump administration’s demands for far-reaching concessions.

Trump’s threat makes going ahead with talks “very difficult politically” for Xi’s government, said Jake Parker, vice president of the U.S.-China Business Council. He said the Chinese public might “view this as a capitulation” if Beijing reached an agreement before Trump’s Friday deadline.

The conflict is testing how far Beijing is willing to go in changing a state-led economic model it sees as the path to prosperity and global influence — and how much power Washington will have to enforce any agreement.

Beijing is willing to change industrial plans that provoke foreign opposition but wants to preserve the ruling Communist Party’s dominant role in directing economic development, said Willy Lam, a politics specialist at the Chinese University of Hong Kong.

Chinese officials have said they are willing to let foreign companies participate in plans that call for government-led creation of global competitors in robotics and other technologies. But they have yet to release details, and it is unclear whether the concessions will satisfy Trump.

Xi is “adamant about party-state control over major sectors of the economy,” Lam said. “If they give this up, then China in effect ceases to be a socialist country.”

Beijing agreed early on to narrow its trade surplus with the United States — a staggering $379 billion last year — by purchasing more American soybeans, natural gas and other exports.

At the same time, Xi’s government has announced a steady drumbeat of promises to open markets — in businesses that include auto manufacturing and banking. But none of the moves directly addresses American complaints.

The negotiators are also looking for a way to hold Beijing to any commitments it makes. The Trump administration wants to keep tariffs on Chinese imports to maintain leverage over Beijing.

“Trump wants a certain amount of tariffs to remain in place just in case the Chinese don’t honor their promises,” Lam said. “The Chinese refuse to give the Americans the right to penalize them.”

The Chinese are also skittish about allowing Washington to dictate changes to industrial policy and subsidies, said Raoul Leering, a trade specialist for Dutch bank ING. They see that as “having another country decide your economic policy.”

Trump also seems to be calculating that Xi needs a deal more than he does. The Chinese economy is decelerating. “Trump believes he can bully the Chinese,” Lam said. “Trump realizes the Chinese economy is facing a rough patch, and Xi Jinping is under pressure from his own people.”

But Trump also has an incentive to reach a deal. The trade war is creating uncertainty for businesses trying to decide where to buy supplies, locate factories and make investments. And it’s been weighing on a strong U.S. stock market, which the president likes to tout as evidence that his economic policies are working.

“We are optimistic generally on reaching an agreement,” said Jason Oxman, president of the tech trade group the Information Technology Industry Council. “We’re optimistic that an agreement can be mutually beneficial.”

Threats from Trump are “just the way he likes to negotiate,” Leering said. “That is a risky but potentially rewarding strategy — so long as the other side doesn’t leave the table.”