(CNN) -- President Donald Trump tweeted Thursday that he will add a new tariff on $300 billion of Chinese-made products on September 1, which would effectively put a tax on all Chinese goods coming into the United States.
"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 products coming from China into our country," he tweeted.
The new tariffs could hit US consumers harder than the earlier rounds. It would tax goods like iPhones and other consumer electronics, sneakers and toys. Last year, Trump imposed tariffs on about $250 billion in Chinese-made goods, targeting industrial materials and components.
Trump issued his new threat of tariffs on China following a mid-morning meeting in the Oval Office with his trade team meant to update him on talks that wrapped this week in Shanghai, according to an administration official familiar with the matter.
The team includes Treasury Secretary Steven Mnuchin and US Trade Representative Robert Lighthizer.
Trump wasn't pleased that China had not offered concrete promises to purchase American agricultural products during the talks, something he believed was agreed to when he met with Chinese President Xi Jinping in June at the Group of 20 summit in Japan, according to the official.
At the time, Trump said he'd put off imposing new tariffs indefinitely."We won't be adding an additional tremendous amount of — we have, I guess, $350 billion left, which could be taxed or it could be tariffed. And we're not doing that," Trump said at the time.
While trade officials told Trump Thursday they believed there is still the potential for a deal to be struck with China, they said they were still far off from coming to any kind of agreement.
Trump issued the four-tweet message announcing new tariffs starting in September with input from Mnuchin and Lighthizer, according to the official.
In his tweets, the President called the talks "constructive," but said the Chinese have not restarted buying American agricultural products as they had promised. He also claimed that China had failed to live up to its commitment in stemming sales of fentanyl, a powerful opioid, into the United States.
American farmers have been hit hard by China's retaliatory tariffs. Once the biggest market for US soybean farmers, the Chinese stopped buying the American product last summer in retaliation to Trump's tariffs. By the end of 2018, the amount of American soybeans sitting in storage hit record levels.
The move to apply new tariffs is sure to increase anxiety among businesses and Wall Street that the trade war is nowhere near its end.
Equity and oil markets took a downward turn after Trump's tweets.
"The business community was surprised by the President's announcement of new tariffs," said Doug Barry, communications director for the US-China Business Council.
"We are concerned that today's actions will drive the Chinese away from the negotiating table," he added.
About 85% of the toys sold in the United States come from China and would be hit by the new tariff. In June, Hasbro president John Frascotti told US trade officials at a hearing that the duty would cause "significant and disproportionate harm" to the company and the broader US toy industry.
Tariffs that go into effect on September 1 could hit some of the toys that companies have already ordered for the holiday season, said Steve Pasierb, president and CEO of The Toy Association.
"We're worried about how much of the 10% tariff will get passed on to consumers across all categories. A lot of things are going to get more expensive, and toys aren't essential goods," he said.
CNN's Cristina Alesci contributed to this report.