President Donald Trump said Thursday that the U. S. is putting 10% tariffs on another $300 billion worth of Chinese goods, effective Sept.1.

"Trade talks are continuing and during the talkes the U.S. will start, on September 1st, putting a small additional trariff of 10% on the remaining 300 billion dollars of goods and products coming from China into our country... We look forward to continuing our positive dialogue with China on a comprehensive trade deal , and feel that the furture between our two countries will be a very bright one!" Trump said in a tweet on Thursday.

The surprise tariff announcement came after the U.S. and China restarted trade talks in Shanghai this week, the first in-person trade talks since a G-20 truce. The White House said Wednesday before this Trump tweet that the meetings were "constructive"adding that China confirmed its commitment to increase  purchase of U.S. agricultural exports. Trade negotiations wil continue in Washington in early Spetember, according to the white house statement.

It's unclear what has caused Trump to end the trade war crease-fire with these new tariffs. The tweet comes in the wake of a meeting Thursday moring at which the president got a report from Treasury Secretary Mnuchin and Trade Representative Rober Lightizer on their metting in Shanghai this week, a White house offical told CNBC's Eamon Javers.

Trump said later in the day taht the new tariffs could be raised to above 25%.

The rade battle between the world's two largest economies has dragged on for more than a year and half. Trump shocked the markets in May by hiking tariffs to 25% from 10% on$200 billion in Chinese goods. China immediatedly retaliated and said a trade deal will not be reached unless the existing duties were stripped.

Chinese purchase of U.S. agricultural products remains a big sticking point in the trade conflict. Trump claimed Thursday that China agreed to buy :in the large quantities, but did not do so.| China, however, insisted millions of tons of U.S. soybeans have been shipped to China since July 19, and many companies have made orders for American soybeans , cotton, pork and sorghum, Chinese state media Xinhua said.