DANANG, Vietnam — President Trump has issued two starkly contradictory calls on his trip to Asia this past week: The nations of the world must rally behind the United States to confront the nuclear threat from North Korea, but they should expect America to go its own way on trade.

Reconciling those messages will be hard, and it may determine the near-term fate of the United States as a Pacific power.

In South Korea on Wednesday, Mr. Trump put on the mantle of a superpower leader. In a speech that crackled with the urgency of a Cold War manifesto, he told lawmakers there, “It is our responsibility and our duty to confront this danger together, because the longer we wait, the greater the danger grows, and the fewer the options become.”

Two days later, in the Vietnamese resort city of Danang, where American troops once came ashore to fight Communist insurgents, Mr. Trump reverted to the protectionist themes of his presidential campaign. “There is no place like home,” he told Pacific Rim leaders, warning them that the United States would never again sign a regionwide trade agreement.

At one level, the contradictory messages illustrate Mr. Trump’s transactional approach to statecraft — one that prizes individual victories over a unified theory of America’s role in the world. That pragmatism is also reflected in his singular brand of leader-to-leader diplomat.

But the contradictions also reflect a more fundamental disarray in the presidency’s policy toward Asia. It seems caught among the geopolitical realism of Mr. Trump’s diplomats and the economic nationalism of his political aides and, to a great extent, Mr. Trump himself.

These competing impulses have left allies and adversaries alike confused about America’s motives and staying power. Over time, several experts said, the balancing act would be impossible to maintain.

Already with China, Mr. Trump has had to soft-pedal his ambitious trade agenda in an uphill effort to persuade President Xi Jinping to do more to press the neighboring North Korean government.

With the smaller nations of Southeast Asia, Mr. Trump may feel less pressure to compromise. His comments in Vietnam lacked the solicitous tone he had used in China and Japan, veering into the defiant populism he used on the campaign trail. Yet his go-it-alone message could drive these countries further into the orbit of China, which has moved at this meeting of Pacific leaders to fill the vacuum left by the United States.


Mr. Trump, right, with other leaders at the Asia-Pacific Economic Cooperation Economic Leaders’ Meeting in Danang, Vietnam, on Saturday. CreditPool photo by Jorge Silva

“The region is looking for a robust American presence, not just on security but on trade,” said John Delury, an associate professor of Chinese studies at Yonsei University in Seoul, the South Korean capital. “For Trump to come with an ‘America First’ agenda leaves Asian leaders in the lurch.”

Jeffrey A. Bader, a former China adviser to President Barack Obama, said Mr. Trump’s words would make Asian leaders “feel that the U.S. is less of a factor in the region.”

“They’re always looking for hedges against local bullies, like China,” he added, “and the U.S. is much less of a hedge.”

Indeed, Mr. Trump was the odd man out at this meeting of the Asia-Pacific Economic Cooperation forum. The other 20 leaders formally endorsed the idea of a liberal trade regime, arbitrated by the World Trade Organization, and condemned moves to erect new barriers.

“We recognize the work of the W.T.O. in ensuring international trade is rules based, free, open, fair, transparent, predictable and inclusive,” the members wrote in their joint statement released on Saturday, using language that American negotiators had reportedly resisted.

On Friday, Mr. Trump railed against the W.T.O., accusing it of treating the United States unfairly. Rather than uphold principles of free trade, he said, it contributed to a systematic exploitation of Americans, in which “jobs, factories and industries were stripped out of the United States.”

While Mr. Trump vowed never to sign a regional trade deal like the Trans-Pacific Partnership, from which he withdrew the United States early in his presidency, the remaining 11 members of that deal agreed on Saturday to press on with it, creating a “broader free-trade area” across Asia that will pointedly exclude the United States.

 As the Pacific leaders gathered here on Saturday, much of the attention focused on whether Mr. Trump would meet with President Vladimir V. Putin of Russia.

The White House steered clear of a formal meeting, though the two men conferred briefly. The United States and Russia later issued a joint statement on Syria that reaffirmed previous commitments to defeat the Islamic State and to untangle conflicts between their respective forces on the Syrian battlefield.

Until Saturday evening, when Mr. Trump unloaded to reporters on Air Force One about Mr. Putin and the investigations into Russian election meddling, this trip had been a surprisingly disciplined exercise for the president.

Still, for Mr. Trump, this trip has been a surprisingly disciplined exercise. Mr. Trump joined the other leaders in wearing matching electric-blue, traditional Vietnamese shirts at dinner on Friday evening, adhering to a peculiar tradition of this summit meeting.


While in Beijing, President Trump lavished praise on President Xi Jinping, only to criticize China’s trade practices a day later in Vietnam. CreditDoug Mills/The New York Times

With a jam-packed schedule, he has tweeted sparingly and has kept generally on message. The White House has cut down on unscripted moments, limiting media access and acquiescing to the Chinese reluctance to allow questions after his joint statements with Mr. Xi.

Mr. Trump’s encounters with leaders have been harmonious — even leaders, like President Moon Jae-in of South Korea, with whom he has differences. That is in keeping with Mr. Trump’s pattern throughout his presidency, though it was perhaps never as striking as in Beijing, where he lavished praise on Mr. Xi, only to criticize China’s trade practices a day later in Vietnam.

“There is some value in treating counterparties with respect, in trying to build relationships with them, despite the distasteful nature if it,” said Mr. Bader, the former Obama official.

But if Mr. Trump’s stops in Northeast Asia were aimed at building a coalition against North Korea, his swing through Southeast Asia seemed calculated to remind people that he has little use for the post-World War II concept of the United States as global leader.

At moments, his speech in Vietnam had the tub-thumping atmosphere of one he may have given in Pennsylvania or Wisconsin. When a member of the audience broke into applause after he accused countries of not opening their markets to American goods, a sardonic Mr. Trump exclaimed: “Funny. They must have been one of the beneficiaries.”

Administration officials framed the speech as a chance for Mr. Trump to promote a “free and open Indo-Pacific,” which the White House has embraced as its answer to Mr. Obama’s “Asia pivot.” But the president put little meat on the bones, emphasizing the sovereignty and independence of nations over common interests or universal rights.

“Human rights are, in essence, an international agreement,” said John Sifton, the director of Asia advocacy for Human Rights Watch. “When he talks about trade in those terms, it suggests that he doesn’t hold the multilateral legal system in very high regard — and that’s frightening.”

Human rights groups, Mr. Sifton said, were focusing their energies on lobbying Canada and Japan rather than the United States.

Chinese leaders do not dwell on human rights either, to say the least. But Mr. Xi came to Vietnam primed to take over some of the ground usually commanded by the American president. During his speech, which came right after Mr. Trump’s, he declared, “Opening up will bring progress, and those who close down will inevitably lag behind.”

In the absence of an alternative sales pitch from the United States, experts said, China will inevitably make further gains.

“China has made significant inroads in cultivating Southeast Asia,” said Tang Siew Mun, head of the Asean studies center at the ISEAS-Yusof Ishak Institute in Singapore. “This isn’t an entirely bad proposition for the region, but China’s success is disastrous for the U.S., as Chinese advances are at the U.S.’s expense.”

“At the end of the day,” Mr. Tang said, “‘America First’ may devolve into the U.S. being home alone.”