A day after the latest round of trade talks ended without a deal, President Trump on Thursday bashed China and said the US would impose 10% tariffs on another $300 billion worth of Chinese goods on Sept. 1.

“Our representatives have just returned from China where they had constructive talks having to do with a future Trade Deal. We thought we had a deal with China three months ago, but sadly, China decided to re-negotiate the deal prior to signing,” the president wrote in one of a series of four tweets a day after a US delegation returned home without a deal.

“More recently, China agreed to buy agricultural product from the US 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!” Trump wrote, again accusing Chinese officials of reneging on promises, a charge they deny.

“Trade talks are continuing, and during the talks the US 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. This does not include the 250 Billion Dollars already Tariffed at 25%,” he continued.

“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!”

US and Chinese negotiators ended a brief round of trade talks in Shanghai on Wednesday with little sign of progress and agreed to meet again in September, prolonging a truce in a year-long trade war between the world’s two largest economies.

Trump’s tweets also came hours after Secretary of State Mike Pompeo ripped China’s actions in Asia after meeting his Chinese counterpart for the first time this year amid the political tension between the two countries.

“We are working with them on many fronts,” Pompeo said at a meeting in Bangkok of the Association of Southeast Asian Nations.

“But we are also very candid about the places we are hoping China will behave in ways that they are not behaving today and we talked about each of those as well.”

After meeting China’s top diplomat, Wang Yi, Pompeo said both countries wanted to improve ties that have soured on issues ranging from trade and sanctions on Chinese telecoms giant Huawei to Taiwan and the busy South China Sea waterway.

Earlier, Wang had struck a more conciliatory tone, saying he and Pompeo had discussed ways to promote China-US ties.

“There may be at various times issues and problems between China and the United States, but no matter how many problems, it is important for both sides to sit down and have face-to-face discussions,” Wang said.

The trade war with China, which the president had said would be easy to win, has slowed both countries’ economies.

With Reuters