NEW YORK — The Chinese were not surprised by President Donald Trump's threats to impose more tariffs on their goods, several experts said Monday — they just assumed it was Trump being Trump.

On Sunday, Trump appeared to imperil the ongoing trade talks with China — sending stock prices on a roller coaster ride Monday — with the surprise announcement that he intended to impose tariffs on almost all goods imported from China by Friday.

“I am not sure how literally Trump’s threat is being taken in Beijing, but he has articulated essentially the same threat before,” William Hurst, a Northwestern University political science professor and an expert on Chinese politics and legal institutions, wrote in an email to NBC News.

“So it is likely not a surprise, except perhaps in its timing.”

And Trump may have inadvertently strengthened the Chinese bargaining position, Hurst said.

“The U.S. seems to want trade negotiations to conclude quickly, whereas it is probably in China’s interest to delay or drag them out as long as possible,” Hurst said.

“I think the Chinese leadership generally views Trump as a weak president with some erratic tendencies,” he added. “Trump is at least potentially useful for China because he is accelerating America’s retreat from the world and alienating erstwhile allies and partners as he does so.”

Trump tweeted his tariff threat Sunday and accused the Chinese of trying “to renegotiate” parts of the deal that both sides were thought to have already agreed on.

For 10 months, China has been paying Tariffs to the USA of 25% on 50 Billion Dollars of High Tech, and 10% on 200 Billion Dollars of other goods. These payments are partially responsible for our great economic results. The 10% will go up to 25% on Friday. 325 Billions Dollars.... — Donald J. Trump (@realDonaldTrump) May 5, 2019

....of additional goods sent to us by China remain untaxed, but will be shortly, at a rate of 25%. The Tariffs paid to the USA have had little impact on product cost, mostly borne by China. The Trade Deal with China continues, but too slowly, as they attempt to renegotiate. No! — Donald J. Trump (@realDonaldTrump) May 5, 2019

Earlier this month, Treasury Secretary Steven Mnuchin and U.S. Trade Representative Robert Lighthizer had characterized the proposed trade deal as “getting into the final laps.”

But Trump tweeted that he would raise import taxes on $200 billion in Chinese products to 25 percent from 10 percent as of Friday. That's on top of a 25 percent duty on another $50 billion of Chinese imports. Beijing had imposed penalties on $110 billion of American goods.

Stock prices initially plunged on Wall Street on Monday amid fears of an all-out trade war between the world’s two largest economies before staging a stunning comeback as investors bet China and the U.S. would reach a trade deal despite Trump — not because of Trump.

Hurst said China is playing a long game against the U.S. while Trump wants to appear that he’s trying to make good on his promise to protect industry in the Rust Belt states he needs to win re-election.

“China hopes to paint Trump and the U.S. not so much as adversaries but increasingly as outliers and antagonists in the international economic and security order,” Hurst said. “If the United States becomes more isolated and less trusted, this weakens any claim to American hegemony. China does not want to topple the United States, but wants to fill some of the space left open as America recedes from its position of global dominance."

The Chinese view Trump “as untrustworthy and difficult,” said Phillip Braun, a Northwestern University finance professor who is an expert on Chinese politics and once served as an adviser to the prime minister of Thailand.

“When he makes announcements like this, it makes it difficult for the Chinese,” he said. “They can’t be seen by their own people as capitulating to Trump.”

The United States has been losing, for many years, 600 to 800 Billion Dollars a year on Trade. With China we lose 500 Billion Dollars. Sorry, we’re not going to be doing that anymore! — Donald J. Trump (@realDonaldTrump) May 6, 2019

So their strategy, Braun said, is basically to let Trump bluster and then resume talking with Mnuchin and Lighthizer.

“In the end, Trump just wants to look good,” Braun said. “The Chinese saw what happened with NAFTA when he threatened Mexico and Canada with tariffs.”

Braun was referring to the North American Free Trade Agreement, which Trump had called the “worst trade deal in the history of the world” when he was running for president.

NAFTA was also deeply unpopular in states such as Michigan, Pennsylvania and Ohio, which had, for generations, seen good-paying manufacturing jobs migrate to Mexico.

In the final months of talks to renegotiate NAFTA, Trump threatened to impose a 25 percent tariff on automobile and auto parts exports to the U.S. from Mexico and Canada.

“Without tariffs we wouldn’t be talking about a deal,” Trump said in October after announcing a new agreement to replace NAFTA called the United States-Mexico-Canada Agreement.

But neither the U.S. nor Mexico and Canada have ratified the new deal.

Meanwhile, China confirmed Tuesday its economy czar will go to Washington for trade talks beginning Thursday.

Vice Premier Liu He is Chinese President Xi Jinping's top economic adviser.

Geng Shuang, a spokesperson for China's foreign ministry, said it was "normal" for there to be differences during negotiations.

"China always believes that mutual respect, equality and mutual benefit are the premise and basis for reaching an agreement," Geng added. "Adding tariffs will not solve any problems."

Dawn Liu contributed reporting from Beijing.