Washington • President Donald Trump said Sunday that he will increase tariffs on Chinese imports on Friday, unexpectedly setting what appears to be a new deadline to produce a comprehensive deal or trigger an escalation of the U.S.-China trade war.

Just days before Chinese negotiators are scheduled to arrive in Washington, the president threatened to increase tariffs on $200 billion worth of Chinese goods from 10 percent to 25 percent on Friday and levy a new 25 percent fee on all remaining Chinese imports shortly.

In a pair of tweets, Trump accused China of trying to "renegotiate" the terms of an agreement that negotiators have been racing to finish for five months.

Chinese Vice Premier Liu He is scheduled to arrive in Washington on Wednesday for what had been billed as potentially the concluding rounds of bargaining.

U.S. officials have said they hoped to wrap up a sweeping deal soon, but Trump's abrupt intervention adds a volatile new element to the end game.

"The Trade Deal with China continues, but too slowly, as they attempt to renegotiate. No!" the president tweeted shortly after noon on Sunday.

The office of the U.S. trade representative, Robert E. Lighthizer, had no immediate response to a request for comment.

The president repeated his mistaken claim that "China has been paying Tariffs to the USA" for 10 months. In fact, American importers pay those import levies.

While Chinese exporters on some occasions may lower their prices and absorb part of the tariffs, several recent studies have concluded that almost the entire financial burden has fallen on the U.S. economy.

"These payments are partially responsible for our great economic results," the president added. Mainstream economists dispute this.

National Economic Council Director Larry Kudlow said Sunday that by announcing the tariff increase, Trump was "issuing a warning" to China.

“I’m a free-trade guy. The president’s tariffs, however, have been extremely useful in negotiating. ... If it doesn’t work out, then I think what the president is saying in today’s tweet is that we will continue these tariffs,” Kudlow said during an appearance on Fox News Channel.

He acknowledged that there are costs to American farmers and consumers when tariffs are imposed, but he maintained that the administration has taken action to help on that front. He also said that "structural issues and enforcement issues remain" when it comes to China's trade practices.

"China has got to end its unfair, nonreciprocal trading system. They're breaking the laws," he said.

U.S. and Chinese negotiators have been meeting for months in an effort to reach a deal that would resolve Trump's complaints about Chinese trade practices and the chronic U.S. trade deficit with China.

The two sides have been closing in on a deal expected to include major new purchases of American goods and a Chinese commitment to abandon efforts to steal or coerce U.S. companies into surrendering their technology trade secrets.

Until the president's tweets, recent administration statements about prospects for a deal had been optimistic.

Treasury Secretary Steven Mnuchin said last week that recent talks in Beijing were "productive," an assessment echoed in an official White House statement.

Last month, Trump said the two sides were on the verge of an “epic” and “monumental” deal that would address all of his complaints about Chinese trade practices. In recent days, there have been indications that he was preparing to weaken key demands, including a reduction in massive Chinese subsidies for state firms.