President Donald Trump on Friday threatened to place an additional 100% tax on Chinese imports starting on Nov. 1 or sooner, potentially escalating tariff rates close to levels that in April fanned fears of a global recession.

The president expressed frustration with new export controls placed on rare earth elements by China - and said on social media that "there seems to be no reason" to meet with Chinese leader Xi Jinping as part of an upcoming trip to South Korea.

Trump later told reporters he had not canceled his meeting. "But I don`t know that we`re going to have it," he said during an Oval Office appearance on another subject. "I`m going to be there regardless, so I would assume we might have it."

Trump also suggested there may be time to ratchet down his steep new tariff threat. "We`re going to have to see what happens. That`s why I made it Nov. 1," he said.

On Thursday, the Chinese government restricted access to rare earth minerals, requiring foreign companies to get special approval for shipping the metallic elements abroad. It also announced permitting requirements on exports of technologies used in the mining, smelting and recycling of rare earths, adding that any export requests for products used in military goods would be rejected.

On social media, Trump described the export controls as "shocking" and "out of the blue." He said China is "becoming very hostile" and that it`s holding the world "captive" by restricting access to the metals and magnets used in electronics, computer chips, lasers, jet engines and other technologies.

Trump said in a post that "starting November 1st, 2025 (or sooner, depending on any further actions or changes taken by China), the United States of America will impose a Tariff of 100% on China, over and above any Tariff that they are currently paying." The president also said the U.S. government would respond to China by putting its own export controls "on any and all critical software" from American firms.

The Chinese Embassy in Washington did not immediately respond to an Associated Press request for comment.

The S&P 500 tumbled 2.7% on worries about the rising tensions between the world`s largest economies. It was the market`s worst day since April when the president last bandied about import taxes this high. Still, the stock market closed before the president spelled out the terms of his threat.

Not only could the global trade war instigated by Trump be rekindled, but import taxes being heaped on top of the 30% already being levied on Chinese goods could, by the administration`s past statements, cause trade to break down between the U.S. and China in ways that could cause growth worldwide to slump.

While Trump`s wording was definitive, he is also famously known for backing down from threats. Earlier this year, some investors began engaging in what the Financial Times called the "TACO" trade, which stands for "Trump Always Chickens Out."

The prospect of tariffs this large could compound the president`s own political worries, potentially pushing up inflation at a moment when the job market appears fragile and the drags from a government shutdown are starting to compound with layoffs of federal workers.

The United States and China have been jostling for advantage in trade talks, after the import taxes announced earlier this year triggered the trade war. Both countries agreed to ratchet down tariffs after negotiations in Switzerland and the United Kingdom, yet tensions remain as China has continued to restrict America`s access to the difficult-to-mine rare earths needed for a wide array of U.S. technologies.

There is already a backlog of export license applications from Beijing`s previous round of export controls on rare earth elements, and the latest announcements "add further complexity to the global supply chain of rare earth elements," the European Union Chamber of Commerce in China said in a statement.

There are other flashpoints in the trade relationship, including U.S. restrictions on China`s ability to import advanced computer chips, sales of American-grown soybeans and a series of tit-for-tat port fees being levied by both countries starting on Tuesday.

Trump did not formally cancel the meeting with Xi, so much as indicating that it might not happen as part of a trip at the end of the month in Asia. The trip was scheduled to include a stop in Malaysia, which is hosting the Association of Southeast Asian Nations summit; a stop in Japan; and a visit to South Korea, where he was slated to meet with Xi ahead of the Asia-Pacific Economic Cooperation summit.

Sun Yun, director of the China program at the Stimson Center, said Beijing`s move was a reaction to U.S. sanctions of Chinese companies this week and the upcoming port fees targeting China-related vessels - but said there`s room for de-escalation to keep the leaders` meeting alive. "It is a disproportional reaction," Sun said. "Beijing feels that de-escalation will have to be mutual as well. There is room for maneuver, especially on the implementation."

Gracelin Baskaran, director of the Critical Minerals Security Program at the Center for Strategic and International Studies in Washington, D.C., said China holds leverage because it dominates the market for rare earths with 70% of the mining and 93% of the production of permanent magnets made from them, which are crucial to high-tech products and the military.

"These restrictions undermine our ability to develop our industrial base at a time when we need to. And then second, it`s a powerful negotiating tool," she said.

Craig Singleton, senior director of the China program at the Foundation for Defense of Democracies, a think tank, said Trump`s post could "mark the beginning of the end of the tariff truce" that had lowered the tax rates charged by both countries.

"Mutually assured disruption between the two sides is no longer a metaphor," Singleton said. "Both sides are reaching for their economic weapons at the same time, and neither seems willing to back down."