WASHINGTON – President Donald Trump expressed optimism Thursday about trade talks with China, but said no agreement will be nailed down until he and Chinese counterpart Xi Jinping meet in the coming weeks.

“This is going to be a very big deal or it’s going to be a deal that we’re going to postpone for a little while," Trump told reporters at the White House during a day of high-level negotiations.

Later, during a meeting with China's top trade negotiator, Trump was read a letter from Xi. "I hope that our two sides will continue to work with mutual respect," the Chinese president wrote.

“That’s a beautiful letter," the U.S. president told his guests.

Trump and aides said he hopes to meet with his Chinese counterpart by a March 1 tariffs deadline, and that it could happen right after his upcoming summit with North Korean leader Kim Jong Un. The administration plans to announce the date and location of the Kim summit next week, Trump said.

The president discussed negotiations with China hours after tweeting that "no final deal will be made until my friend President Xi, and I, meet in the near future to discuss and agree on some of the long standing and more difficult points."

Administration officials met this week with a China delegation to discuss a new trade agreement. Trump himself met with the head of the delegation, Chinese Vice Premier Liu He.

The U.S. and China hit each other with tariffs last year, spawning fears of a trade war that could damage the global economy. Trump and his advisers have accused the Chinese of unfair trade practices, from government subsidies to intellectual property theft, claims the Chinese have consistently denied – all issues that are the subject of ongoing negotiations.

Late in the year, Trump and Xi agreed to stop further tariffs and hold negotiations for a new overall trade agreement.

They set a deadline of March 1, after which new tariffs would go into effect if no agreement is reached.

In a written statement, the Trump administration said it raised several issues with the Chinese, including "the ways in which United States companies are pressured to transfer technology to Chinese companies." Other topics included intellectual property rights, Chinese trade barriers against the United States, subsidies of Chines businesses, and cyber-theft.

"While progress has been made, much work remains to be done," the statement said.

It added that March 1 remains "a hard deadline," and that the U.S. will hit China with new tariffs if no agreement is reached by then.

Negotiators are “certainly” talking about intellectual property theft, the rules regarding the financial services of each country, and the opening of Chinese markets to U.S. farmers and manufacturers, Trump said.

"We’re going to go into everything," Trump said during a meeting with manufacturers about a new "Buy American" initiative, and these topics will come up in a meeting with Xi.

A conference between the U.S. and Chinese presidents could be part of a larger Asia trip for Trump. Aides are also negotiating a second summit with Kim in late February, part of an effort to get him to give up North Korea's nuclear weapons.

Expressing optimism in a brief tweetstorm Thursday, Trump said the meetings "are going well with good intent and spirit on both sides. China does not want an increase in Tariffs and feels they will do much better if they make a deal. They are correct."

Trump later laid down markers for a new agreement. In a tweet, he said he is "looking for China to open their Markets not only to Financial Services, which they are now doing, but also to our Manufacturing, Farmers and other U.S. businesses and industries."

He added: "Without this a deal would be unacceptable!"

Chinese officials agreed to purchase 5 million metric tons of U.S. grown soybeans. To put that in context, Beijing imported 32 million metric tons of U.S. soybeans in 2017, according to the U.S. Joint Economic Committee.

The Chinese have also proposed a Trump-Xi summit on trade, offering up the city of Hainan as a site and saying it could be done after the Trump-Kim meeting, The Wall Street Journal reported.

While saying he expects to meet with Xi to nail down a new agreement, Trump also left an implied threat to the Chinese.

"Tariffs on China increase to 25 percent on March 1st," he said, "so all working hard to complete by that date!"

Contributing; John Fritze