President Trump said Thursday that he would place tariffs on $300 billion worth of Chinese goods starting in September, claiming that China was refusing to live up to prior promises made in the trade talks. The president first said the tariffs would be set at 10%, and then said later Thursday afternoon they could be applied at 25%.

The announcement follows the return of U.S. Trade Representative Robert Lighthizer and Treasury Secretary Steven Mnuchin from a two-day trip to Shanghai to get trade negotiations back on track with Beijing.

In a series of tweets Thursday afternoon, Trump indicated that no progress had been made in those talks and he would therefore impose the additional tariffs he had previously threatened earlier in the year.

...We look forward to continuing our positive dialogue with China on a comprehensive Trade Deal, and feel that the future between our two countries will be a very bright one! — Donald J. Trump (@realDonaldTrump) August 1, 2019

"China agreed to buy agricultural product from the U.S. in large quantities, but did not do so. Additionally, my friend President Xi said that he would stop the sale of Fentanyl to the United States — this never happened, and many Americans continue to die!" he tweeted. "Trade talks are continuing, and during the talks the U.S. will start, on September 1st, putting a small additional Tariff of 10% on the remaining 300 Billion Dollars of goods and products coming from China into our Country."

Trump later told reporters as he left the White House for an event in Ohio, though, that the rate could be set as high as 25% or even higher.

The U.S. currently has tariffs of 25% on $250 billion worth of Chinese goods. Placing tariffs on another $300 billion would effectively put levies on all goods coming in from China. Trump had previously threatened to impose the additional 10% tariffs on China following a May breakdown in trade negotiations. Trump said China had to restore concessions it had made earlier in the negotiations, concessions Beijing denied it ever made.

Trump put the tariffs on hold following one-on-one talks with Chinese President Xi Jinping in late June during the G-20 Summit in Japan, indicating a cooling-down. Thursday's announcement indicated that the talks were breaking down again, with Trump repeating prior accusations against Beijing. "We thought we had a deal with China three months ago, but sadly, China decided to re-negotiate the deal prior to signing," he tweeted.

Just the day before, the White House said that Lighthizer and Mnuchin's trip had been "constructive" and Beijing had "confirmed their commitment to increase purchases of United States agricultural exports." The administration made no announcement of what goods were going to be purchased and hasn't since then.

The same day, Chinese Foreign Ministry spokeswoman Hua Chunying told reporters that the U.S. hadn't shifted its demands, blocking progress in the talks. “I believe it doesn’t make any sense for the U.S. to exercise its campaign of maximum pressure at this time," she said.