Trump, speaking at the White House during a meeting with Chinese Vice Premier Liu He, said he was optimistic that the world’s two largest economies could reach “the biggest deal ever made.”

The Chinese trade delegation said in a statement that the talks made “important progress,” China’s official Xinhua news agency reported.

No specific plans for a meeting with Xi were announced, but Trump said there could be more than one. U.S. Trade Representative Robert Lighthizer and Treasury Secretary Steven Mnuchin were invited to bring a U.S. negotiating team to Beijing around mid-February, with dates still pending.

The White House also said in a statement that its scheduled March 2 tariff increase on $200 billion of Chinese goods was a “hard deadline” if no deal was reached by March 1.

At the end of the talks next door to the White House, Liu told Trump that China would make a new, immediate commitment to buy more U.S. soybeans.

An administration official later clarified the amount as a total of 5 million tonnes, effectively doubling the amount bought by China since resuming limited purchases in December.

U.S. soybean sales to China, which totaled 31.7 million tonnes in 2017, were largely cut off in the second half of last year by China’s retaliatory tariffs and the announcement drew a positive reaction from Trump, who said it would “make our farmers very happy.”

The Chinese delegation said China will expand imports of U.S. agricultural, energy, service and industrial products, according to Xinhua.

While China has previously offered increased purchases of U.S. farm, energy and other goods to try to resolve the trade disputes, negotiators also dug into thornier issues, including U.S. demands that China take steps to protect American intellectual property and end policies that Washington says force U.S. companies to turn over technology to Chinese firms.