Ahead of the high-stakes meeting between President Trump and Xi Jinping of China on Thursday, world leaders were hoping for news of an economic truce that could help stabilize the global economy. They got it.
They got something extra, as well: intensified concerns about whether the world is entering a new era of nuclear weapons proliferation among global powers.
After a 90-minute face to face meeting in South Korea, Mr. Trump announced that the two leaders had sharply de-escalated their trade standoff, agreeing, in essence, on a yearlong cease-fire that would roll back tit-for-tat measures including steep tariffs and shutting off access to rare earth metals.
The meeting was the most anticipated and consequential event of Mr. Trump’s nearly weeklong tour through Asia, where he engaged in a series of trade and security agreements with other countries in the region, many of them geared toward containing Beijing.
“I guess on the scale from 0 to 10, with 10 being the best, I would say the meeting was a 12,” Mr. Trump said aboard Air Force One as he returned to Washington.
The agreement was a win for the world economy, but was brokered under the shadow of a new and sudden amplification of nuclear threats between global powers.
Just minutes before he landed in Busan, South Korea, to meet with Mr. Xi, Mr. Trump announced on social media that the United States would immediately restart nuclear weapons testing after a lull of more than 30 years. The announcement came after Russia announced that it had also conducted tests of a nuclear-capable missile and sea drone this week.
“Because of other countries testing programs, I have instructed the Department of War to start testing our Nuclear Weapons on an equal basis,” he wrote, saying the process would begin immediately.
Mr. Trump did not provide any further details about the decision. But with his message, Mr. Trump seemed to be ratcheting up pressure as he prepared to meet with the leader with the world’s second- largest economy and third-largest nuclear arsenal.
After the meeting, Mr. Trump praised Mr. Xi as a “tremendous leader of a very powerful country.” And he appeared to soften his hard-edged statement from earlier in the day, suggesting that his announcement was not aimed at China but at other nations that he repeatedly declined to name.
“We have more nuclear weapons than anybody, we don’t do testing,” Mr. Trump said. “We’ve halted it years — many years ago,” he said. “But with others doing testing, I think it’s appropriate that we do also.”
But the chaotic backdrop to the meeting was a reminder of how Mr. Trump’s approach to issues and diplomacy can change on a dime — even on a matter as vital as the strategy governing the American nuclear arsenal — and also displayed his increasingly volatile approach to foreign policy since he retook office.
The meeting also drove home how much is at stake every time the United States and China meet now: the global economy, security across the world and the sprawling implications of negotiation between the two countries, affecting everything from individual alliances in the Indo Pacific to the outcome of the Russian invasion in Ukraine.
A readout issued by the Chinese official news agency Xinhua after the meeting did not address what agreements were made but did allude to China’s recent move to cut off supplies of critical minerals.
The statement noted that Mr. Xi told Trump that recent “twists and turns” in the U.S.-China relationship should be a lesson to them both to avoid the “vicious cycle of mutual retaliation.”
The meeting concluded with clear victories for Mr. Trump’s foreign and domestic agenda.
Mr. Trump told reporters on Air Force One that China had agreed to suspend for a year its limits on exports of rare earth metals, which are crucial for a wide range of advanced manufacturing industries. The move by China earlier this month to restrict the exports had prompted Mr. Trump to threaten to cancel this week’s meeting.
He also said that Mr. Xi had agreed to take stronger action to stop the flow of precursor chemicals for making fentanyl and that the United States in response would reduce to 10 percent, from 20 percent, the fentanyl-linked tariffs it had imposed on China early this year. Reducing fentanyl deaths in the United States has been a priority for Mr. Trump.
In a social media post, Mr. Trump said that Mr. Xi had also committed to purchasing a “massive amounts of Soybeans” and other agricultural products, adding that “Our Farmers will be very happy!” He wrote that China would also “begin the process” of purchasing American energy.
While Mr. Trump greeted Mr. Xi warmly ahead of their talks at a military base in Busan, the mood was more fraught than it had been when he met the leaders of Japan and South Korea earlier this week.
For Mr. Trump, his five days in Asia beforehand had largely been about gathering honors and securing trade deals quickly. On Thursday, the tour took a sober turn as he encountered Mr. Xi, even as he called him a “friend of mine.”
Before meeting, the two leaders tensely shook hands in front of a row of Chinese and American flags at an air base in Busan, with Mr. Trump doing the talking and Mr. Xi staying largely silent.
“President Xi is a great leader of a great country, and I think we’re going to have a fantastic relationship for a long period of time,” Mr. Trump said.
Mr. Xi, for his part, approached the meeting with caution and steeliness. In his remarks, Mr. Xi likened China-U.S. relations to a “giant ship” that requires steady joint leadership.
Mr. Xi also said that he and Mr. Trump “do not always see eye to eye with each other” and said it was “normal for the two leading economies of the world to have frictions now and then.”
He also suggested that he would not bend to Mr. Trump’s “America First” agenda. “I always believe that China’s development goes hand in hand with your vision to make America great again,” Mr. Xi said.
Before their private meeting, the two leaders said they were focused on the long list of trade negotiations before them, and signaled they would ignore far graver concerns, including the resumption of nuclear testing among hotly competing countries and Mr. Xi’s interest in putting more distance between America and Taiwan.
Mr. Xi did not respond to a question about whether he would raise the issue of Taiwan at the meeting. Mr. Trump did not answer a question about why he had ordered nuclear weapons testing to resume for the first time in 33 years. The president paused before declining to answer the question, a rare reaction for an almost always spontaneous leader.
Mr. Trump said after the meeting that the issue of Taiwan did not come up during the leaders’ discussion. On Wednesday, Mr. Trump told reporters aboard Air Force One that he did not expect it to, and he would not say whether or not he supported independence for the self-governed island, which China claims as its own.
The two leaders discussed partnering to address other conflicts, he said. Mr. Trump said that he and Mr. Xi had discussed the war in Ukraine at length and that they were “going to work together to see if we can get something done.”
Mr. Trump, who has pressured other nations to stop purchasing Russian oil, which is helping to fund its invasion of Ukraine, noted that Mr. Xi had been buying oil from Russia for a long time but said they did not really discuss the topic.
Mr. Trump’s announcement that he would resume nuclear testing came after President Vladimir V. Putin of Russia said that his country had successfully tested a nuclear-powered and nuclear-capable missile, and then, separately, a nuclear sea drone that could set off a tsunami. And Mr. Xi is overseeing one of the fastest buildups of a nuclear arsenal on Earth.
Asked whether he believed his directive would create a riskier nuclear environment, Mr. Trump brushed off its impact saying, “I think we have it pretty well locked up.”
Mr. Trump added that the United States was already in talks with Russia about denuclearization and that “China would be added to that.”
Mr. Trump’s announcement also came after he had made substantial announcements about building the defenses of American allies in the region.
At a naval base near Tokyo on Tuesday, Mr. Trump said that the Japanese government had placed an order of American-made missiles to arm their fighter jets. His administration has been pressuring the Japanese to spend more on military defense.
Standing next to him, Prime Minister Sanae Takaichi of Japan promised that she had renewed her resolve “to make the Indo-Pacific free and open,” a reference to checking Chinese maneuvers and territorial ambitions in the South China Sea.
In South Korea, Mr. Trump highlighted the country’s investment in American shipbuilding and said later that he had given the U.S. ally “approval to build a nuclear powered submarine.”
By the time he arrived in Busan, Mr. Trump was hoping that he had collected enough leverage for an agreement with Mr. Xi and was looking for more chances to engage.
Throughout his trip, Mr. Trump struck a hopeful tone about striking a deal that could bolster a fragile trade truce that the United States and China struck last month after four rounds of negotiations. As he flew back to Washington, Mr. Trump declared victory.
He called the meeting “a great success” and announced that he would visit in China in April.
“The whole relationship is very, very important,” he said.
David Pierson contributed reporting from Busan, David E. Sanger from Washington, and Lily Kuo from Taipei.
