DA NANG, Vietnam — President Trump is on a diplomatic trip to Asia, but at times Friday it sound like just another campaign speech about trade. 

Speaking before the Asia-Pacific Economic Cooperation summit in Vietnam, Trump echoed his 2016 stump speech by complaining that too many countries take advantage of the United States on trade, and vowing to change that. 

President Trump is pictured speaking at the Asia-Pacific Economic Cooperation (APEC) Summit in Danang, Vietnam.

"I am always going to put America first the same way that I expect all of you in this room to put your countries first," Trump told APEC.

Claiming that some trading partners are not playing by the rules — but not citing any by name — Trump pledged to crack down on closed markets, predatory practices, currency manipulation, intellectual property theft, high trade deficits, and other alleged practices.

"In the end," he said, "unfair trade undermines us all."

As he did in China, a key stop in his 12-day tour of Asia, Trump said he did not blame other countries for taking advantage of the United States — the fault, he said in more comments reminiscent of Campaign '16, lies with previous presidents.

"I wish previous administrations in my country saw what was happening and did something about it," Trump said. "They did not, but I will."

While Trump attended the APEC summit to argue for new trade rules and lobby against North Korea, one potential event fell through: A formal meeting with Russia President Vladimir Putin.

As Air Force One landed midday in this seaside Vietnamese city, White House officials announced that the schedule would not permit a formal meeting between Trump and Putin; they did not rule out an informal chat by the leaders, possibly on North Korea and other issues.

"Are they going to bump into each other and say hello?" said spokeswoman Sarah Huckabee Sanders. "Certainly possible and likely." 

In his speech to the APEC summit, Trump promoted the idea of "free and open Indo-Pacific" region based concepts like the rule of law, private enterprise, and "trade reciprocity." He called on allies to work together to defeat terrorism and stop North Korea's nuclear weapons program.

Trump spoke to APEC as officials in member countries wondered — not unlike the president's critics back in the U.S. — about the meaning of his "America First" rhetoric and his decision to walk away from a major regional trade deal.

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Some of these officials criticized Trump early in his term for pulling the United States from the Trans-Pacific Partnership, a trade deal involving a dozen Pacific Rim nations. The remaining 11 nations are now talking about forming their own trading bloc, without the U.S.

In his speech to APEC, Trump said the United States would no longer engage in big, multi-lateral trade agreements like TPP, saying they undercut national sovereignty. Instead, he said, the U.S. would focus on bilateral, one-on-one trade agreements with individual countries.

Officials in other countries, however, say they are unsure if the Trump administration is very committed to any trade relationship.

"There are going to be questions about how assertive or what exact approach he’s going to take to bilateral economic relations," said Matthew P. Goodman, senior adviser for Asian economics with the Center for Strategic & International Studies in Washington, D.C.

Trump did not call out other nations by name, and in fact praised APEC members ranging from Vietnam to the Philippines for their various contributions to the global  economy.

He was less kind toward the World Trade Organization, complaining about the way it enforces global rules: "Simply put, we have not been treated fairly by the World Trade Organization."

The president bragged about his recent visit to China, in this case using language very different from his campaign. Back then, Trump ripped the Chinese for currency manipulation, and accused it of using trade to "rape" the United States.

On Friday, he talked about his "really productive" meetings with Chinese President Xi Jinping.

Xi, who welcomed Trump to Beijing with great fanfare, also spoke at APEC and offered a very different message than Trump. Extolling globalization, Xi said China would “continue to build an open economy and work hard to achieve mutual benefits" involving other countries.

The trade issue is a big reason Trump is president.

Trump voters in industrial areas of states like Pennsylvania, Michigan, and Wisconsin blamed free trade for factory closures and job losses. Trump spoke to this feeling in his campaign, and his wins in those streets gave him an Electoral College victory over Hillary Clinton.

Trump has used campaign rhetoric throughout his Asia sojourn. In Japan, South Korea, and China, Trump talked about the rising stock market and cited the one-year anniversary of Election Night.

During an appearance with South Korea President Moon Jae-in, Trump said, "it was great victory, and a victory that made a lot of people very happy."

At one point, Trump's APEC speech resembled one of his campaign rallies when a heckler appeared to challenge his claim of unfair trade practices. "Funny," Trump replied. "They must have been one of the beneficiaries. What country do you come from, sir?"

After his speech, Trump met with a group of veterans who fought in the Vietnam War. In the evening, Trump participated in a formal APEC welcoming ceremony and gala dinner.

As he did during the campaign, as he has during the Asia trip, Trump also tweeted about his experiences.

Trump also used his APEC speech to talk about another goal of his Asia trip: Getting more countries to apply more economic and political pressure on North Korea, while trying to force the reclusive nation to give up its nuclear weapons.

Saying that national security and economic security are linked, Trump also called on the world to rally against "radical Islamic terrorism."

The APEC summit is the first of three economic conferences that will cap Trump's trip to Asia.

In the Philippines in a few days, Trump plans to attend an Association of Southeast Asian Nations conference as well as a meeting of the East Asia Summit.