U.S. President Donald Trump said Wednesday that China "broke the deal" in the ongoing U.S.-China trade talks.

Speaking at a rally in Florida, the president attributed his recent threat of increased tariffs to Beijing's negotiating position.

"By the way, you see the tariffs we're doing? Because they broke the deal. They broke the deal," Trump said. "So they're flying in, the vice premier tomorrow is flying in — good man — but they broke the deal. They can't do that, so they'll be paying."

Over the weekend, Trump surprised markets by threatening in a Twitter post that he would significantly raise American levies on Chinese goods — with a first increase this coming Friday, and another "shortly."

The president said trade talks with China had been moving "too slowly" as Beijing tried to re-negotiate. That came as a shock to many observers since recent reports had indicated the world's two largest economies could be set to sign an agreement as early as this week.

Trump added that the United States "won't back down until China stops cheating our workers and stealing our jobs."

"That's what's going to happen. Otherwise, we don't have to do business with them," he said. "We can make the product right here if we have to — like we used to."

Chris Rupkey, managing director and chief financial economist at global financial group MUFG, wrote in a note responding to Trump's Wednesday evening speech that markets may continue to be roiled by that sort of rhetoric: "We are not sure who the president is addressing tonight in a campaign rally, but he is sure scaring the daylights out of the financial markets."

China, for its part, said earlier Wednesday that Beijing will retaliate if U.S. tariffs on $200 billion of Chinese goods are hiked to 25% from 10% as Trump had threatened.

"The escalation of trade friction is not in the interests of the people of the two countries and the people of the world," the ministry said. "The Chinese side deeply regrets that if the US tariff measures are implemented, China will have to take necessary countermeasures."