If the credo of the new U.S. president is “America first,” as Donald Trump emphatically declared Friday in his strikingly nationalistic inaugural address, then where does that leave the rest of the world? 

That is what people around the globe — from Latin America to the Middle East to Asia — were left to wonder after watching Trump use the opening minutes of his presidency to double down on campaign pledges to end what he sees as misguided efforts to help other countries at the expense of U.S. interests. 

After more than 70 years of vigorous political, diplomatic, economic and military engagement to promote Pax Americana, Trump’s words suggested to international observers a far more isolationist and protectionist path ahead.

“If he follows through — and people have to come to terms with the fact he may well do what he says he’s going to do — then it’s the end of the post-World War II, post-Cold War order and the beginning of a new phase,” said Ian Kearns, co-founder of the London-based European Leadership Network.

But that phase, Kearns said, may be far rockier for the United States than Trump suggests.

“If you’re just out to defend your interests,” he said, “then others will do the same.” 

Within minutes of Trump’s speech Friday, others were already having their say.

Although world leaders showered Trump with a cascade of politely worded tweets and congratulatory messages, the mood on the streets in many world cities was far more unsettled on the day that Trump became U.S. commander in chief.

In London, hundreds of people gathered in the evening chill to chant “Dump Trump!” outside the U.S. Embassy. In Mexico City, residents took to social networks to debate not whether Trump was good or bad but how grave the new era might be. And in Beirut, observers compared Trump’s speech to those by their region’s past and present despots.

There was also praise. Many Russians rejoiced, as did anti-European Union populists and Israeli officials. 

The world’s divided response mirrored the one in the United States — defiance and despair in some quarters, enthusiasm and optimism in others, and profound polarization as far as the eye can see.

But perhaps not surprisingly for a president who came to office on a wave of insults hurled across national borders, the world’s protests were more pronounced than its victory parties.

Mexicans awoke Friday to the realization of what many consider a political nightmare — the inauguration of an American president who has taken aim at their economy, their migrants and their shared border.

Literary critic Christopher Domínguez Michael published an op-ed in El Universal simply called, “The saddest day.”  

Another columnist in El Universal, Carlos Heredia Zubieta, wrote: “We are immersed in a cultural war. For the first time in decades, the affront unites Mexicans of all social classes.” 

Trump’s address — more scripted than his campaign speeches but no less bombastic — left many around the world in open-mouthed wonder.

“I listened to Trump’s inauguration speech dubbed on an Arabic channel — it could easily have been Saddam, Assad or Sisi,” tweeted Mohamad Bazzi, a professor of journalism at New York University who is in Beirut, referring to the late ruler of Iraq and the current presidents of Syria and Egypt.

Nathalie Klüver, a Twitter user from the northern German city of Lübeck, appeared to echo the thoughts of many Germans when she tweeted, “If a German chancellor said at an #inauguration that he wants to make Germany great again — that’s unimaginable.”

Demonstrations spanned the globe and were generally small but spirited.

After dark in London — as Trump finished speaking — hundreds of placard-bearing protesters massed at the U.S. Embassy to vigorously chant their dismay. 

“It’s cold. It’s dark. I’d rather be at home in the warm. But I’m here because I’m only an ordinary person, and I’m frightened,” said 65-year-old retiree Stephanie Clark, mentioning nuclear weapons and climate change as particular areas of concern. “I’m frightened of what Donald Trump and his administration can do.” 

There was an edgier tone to protests in the Philippine capital of Manila, where protesters burned an American flag and called on President Rodrigo Duterte to distance himself from Trump.

Marches were also staged in the West Bank city of Nablus, where hundreds of residents paraded Palestinian flags and voiced concern with Trump’s seeming shift toward Israel, including his promise to move the U.S. Embassy to Jerusalem.

“He’s not a man of peace,” said 53-year-old Moussa al-Bitouni, who watched as the inauguration was broadcast live in a smoky East Jerusalem cafe. “He doesn’t want to take the path of peace or talk about peace.”

The mood was very different in Israeli settlements, where Trump’s ascension to the highest U.S. office was greeted with relief and hopeful expectation. 

A delegation of settler leaders was in Washington to attend the inauguration as VIP guests, their presence representing a striking turnabout: For decades, U.S. presidents — Democrat and Republican — have been highly critical of settlement building. Trump, by contrast, has appointed a vocal advocate and fundraiser for the settlements as his ambassador to Israel.

“Congrats to my friend President Trump,” tweeted Israeli Prime Minister Benjamin Netanyahu. “Look fwd to working closely with you to make the alliance between Israel&USA stronger than ever.”

In another sign of the changed geopolitical landscape, anti-E.U. leaders were also welcomed at the inauguration. Nigel Farage, who helped lead the campaign for Britain’s E.U. exit, was in Washington as an honored guest and hosted a pre-inauguration party Thursday night. Trump has said he is indifferent to the E.U.’s fate, unlike his recent predecessors, who have been staunch backers of European integration.

“The old order wasn’t working,” Farage said on a broadcast for the British radio station LBC. “I think it’s going to be great. I think it’s going to be huge. I wish [Trump] well.”

Far-right French politician Marine Le Pen — leading some polls in the French presidential race due in the spring — was similarly exuberant, declaring that Trump’s election had opened “a new era in the cooperation between nations.”

The response among Europe’s establishment was less sympathetic.

“Hostile inauguration speech,” former Belgian prime minister Guy Verhofstadt wrote on Twitter. “We can’t sit around & hope for US support & cooperation. Europe must take its destiny & security in its own hands.”

Many European leaders offered perfunctory notes of congratulations. Some appeared to be trying to will Trump to behave like a conventional U.S. president.

“With great power comes great responsibility,” Lithuanian President Dalia Grybauskaite wrote in Twitter. “Confident in global leadership of the USA! Congratulations @realDonaldTrump!”

There was also apprehension in China — though the government was being careful with its response.

China’s foreign ministry has generally maintained an outward appearance of calm in the run-up to Trump’s inauguration, mostly declining to rise to the bait after some of Trump’s most strident tweets. Behind the scenes, though, diplomats in Beijing say the government is very nervous about the prospect of a Trump administration.

The English-language China Daily newspaper said it hoped Trump could display “more statesmanship” after his inauguration but warned that he was “playing with fire” in trying to open the one-China question.

“If Trump is determined to use this gambit on taking office, a period of fierce, damaging interactions will be unavoidable, as Beijing will have no choice but to take off the gloves,” it wrote in an editorial

China’s censors recently ordered the nation’s media not to indulge in unauthorized criticism of Trump, according to China Digital Times, a website that tracks censorship directives.

In Moscow, Trump was toasted with champagne at an upscale party stocked with politicians, analysts, activists and journalists. The applause was warm when Trump took the oath.

“It’s going to be a lot of action, drive, excitement,” said Dmitry Nosov, a sturdily built former Olympian and former member of the Russian parliament who wore a gray-checked blazer with a bear pin. “Not dull like it has been.”

Karla Adam in London; Annie Gowen in Jaipur, India; James McAuley in Paris; Liz Sly in Beirut; Ruth Eglash and Loveday Morris in Jerusalem; Stephanie Kirchner in Berlin; Simon Denyer in Beijing; Joshua Partlow in Mexico City; and Andrew Roth in Moscow contributed to this report.