When Donald J. Trump won a return to the White House, many countries thought they knew what to expect and how to prepare for what was coming.

Diplomats in world capitals said they would zero in on what his administration does, rather than what Mr. Trump says. Bigger nations developed plans to soften or counter his threat of punitive tariffs. Smaller countries hoped they could simply hide from four more years of gale-force America First.

But it’s getting harder for the world to keep calm and carry on.

At Tuesday’s news conference at Mar-a-Lago, Mr. Trump declined to rule out the use of force in a potential land grab for Greenland and the Panama Canal. He vowed to rename the Gulf of Mexico the “Gulf of America.” He also said he could use “economic force” to turn Canada into the 51st state as a matter of American national security.

For those eager to parse substance from bluster, it looked like another performance of scattershot bravado: Trump II, the sequel, more unrestrained. Even before taking office, Mr. Trump, with his surprising wish list, has stirred up “here we go again” commentary from across the globe.

Beyond the chatter, however, are serious stakes. As the world prepares for Trump’s return, the parallels between his preoccupations and the distant age of American imperialism in the late 19th century are becoming more relevant.

Mr. Trump has already championed the era for its protectionism, claiming that the United States in the 1890s “was probably the wealthiest it ever was because it was a system of tariffs.” Now, he seems to be adding the focus from the 19th and early 20th centuries on territorial control.

What both epochs share is a fear of shaky geopolitics, and the threat of being locked out of territory with great economic and military importance. As Daniel Immerwahr, an American historian at Northwestern University, put it: “We are seeing a reversion to a more grabby world.”

For Mr. Trump, China looms — ready, in his view, to take territory far from its own borders. He has falsely accused Beijing of controlling the American-built Panama Canal. There is also the specter, more grounded in reality, of China and its ally Russia moving to secure control over Arctic sea routes and precious minerals.

At the same time, competition is increasing all around, as some nations (India, Saudi Arabia) rise and others (Venezuela, Syria) spiral and struggle, creating openings for outside influence.

In the 1880s and ’90s, there was also a scramble for control and no single dominant nation. As countries became more powerful, they were expected to physically grow, and rivalries were redrawing maps and causing conflicts from Asia to the Caribbean.

The United States mirrored Europe’s colonial designs when it annexed Guam and Puerto Rico in 1898. But in larger countries, like the Philippines, the U.S. chose indirect control by negotiating deals to advance preferential treatment for American businesses and its military interests.

Some believe that Mr. Trump’s fixation on Greenland, the Panama Canal and even Canada are a one-man revival of the debate over expansionist pursuits.

“This is part of a pattern of the U.S. exerting control, or trying to, over areas of the globe perceived to be American interests, without having to summon up the dreaded words ‘empire,’ ‘colonies’ or ‘imperialism,’ while still extracting material benefits,” said Ian Tyrrell, a historian of American empire at the University of New South Wales in Sydney, Australia.

Mr. Trump’s threats of territorial takeover may be simply a transactional starting point or some kind of personal wish. The United States already has a deal with Denmark that allows for base operations in Greenland.

His suggestion of Americanization there and elsewhere amounts to what many foreign diplomats and scholars see as an escalation more than a break with the past. For years, the United States has been trying to curtail Chinese ambitions with a familiar playbook.

The Philippines is again a focus, with new deals for bases the American military can use in any potential war with Beijing. So are the sea routes that matter most for trade both in Asia and around the Arctic as climate change melts the ice and makes navigation easier.

“What the U.S. always wanted was access to markets, lines of communication and capacity for forward projections of material power,” Professor Tyrrell said.

But for some regions in particular, past as prologue inspires dread.

Panama and its neighbors tend to see Mr. Trump’s comments as a blend of both the 1890s and the 1980s, when the Cold War led Washington to meddle in many Latin American countries under the guise of fighting Communism. The Monroe Doctrine, another 19th-century creation that saw the United States treat the Western Hemisphere as its exclusive sphere of influence, has re-emerged into relevance alongside tariffs and territorial deals.

Carlos Puig, a popular columnist in Mexico City, said Latin America was more worried about Mr. Trump’s return than any other part of the world.

“This is Trump, with majorities in both houses, after four years complaining, a guy that only cares about himself and winning at all cost,” Mr. Puig said. “Not easy for a guy like that not to show that he is trying to fulfill his promises, no matter how crazy they are. I am not so sure everything is just bullying and almost comic provocations.”

But how much can Mr. Trump actually achieve or damage?

His news conference in Florida mixed vague threats (“It might be that you’ll have to do something”) with messianic promises (“I’m talking about protecting the free world”).

It was more than enough to awaken other nations, drawing rapt attention and resistance even before he has taken office.

The French foreign minister, Jean-Noël Barrot, on Wednesday warned against threatening the “sovereign borders” of the European Union — referring to Denmark’s territory of Greenland. He added that “we have entered an era that is seeing the return of the law of the strongest.”

What may be harder to see from Mar-a-Lago but is much discussed in foreign capitals: Many countries are simply tired of the America Mr. Trump wants to make great again.

While the United States is still a dominant force, it has less leverage than in the 1980s or the 1890s, not just because of China’s rise, but because of what many nations see as America’s own drift into dysfunction and debt, coupled with the surge in development by other countries.

The international system the United States helped set up after World War II prioritized trade in hopes of deterring conquest — and it worked well enough to build paths to prosperity that made American unilateralism less potent.

As Sarang Shidore, the director of the global south program at the Quincy Institute for Responsible Statecraft in Washington, explained, many developing nations “are savvier, more assertive and capable even as the U.S. has become less predictable and stable.”

In other words, today the world is unsettled. The postwar equilibrium is being shaken by wars in Europe and the Middle East; by the autocratic partnership of China, Russia and North Korea; by a weakened Iran that is seeking nuclear weapons; and by climate change and artificial intelligence.

The end of the 19th century was turbulent, too. The mistake Mr. Trump may be making now, according to historians, is thinking that the world can be calmed and simplified with additional U.S. real estate.

The protectionist, imperialist age Mr. Trump seemingly romanticizes blew up when Germany and Italy tried to muscle in for a greater share of the world. The result was two world wars.

“We saw how that went with 20th-century weaponry,” said Mr. Immerwahr, the author of “How to Hide an Empire: A Short History of the Greater United States.” “It’s potentially far more dangerous in the 21st.”

For more than a year, almost two million Palestinians living in Gaza have been homeless, facing severe food and medical shortages and under enduring threat of Israeli airstrikes. Nearly 46,000 Gazans have been killed, local health officials said on Wednesday, in a landscape largely reduced to rubble.

So when President-elect Donald J. Trump vowed that “all hell will break out in the Middle East” if hostages taken from Israel during the Hamas-led attacks of Oct. 7, 2023, are not freed in the next two weeks, Gazans were left to wonder: if this is not hell, then what is?

“I am not sure he understands the situation here — it is already hell,” said Alaa Isam, 33, from Deir al Balah, in central Gaza.

Negotiations to end the war between Israel and Hamas have made little progress, leaving civilians in Gaza caught in the crossfire with little hope for the future.

“We have been being killed for 15 months,” Mr. Isam said. “We have been through two cold winters in tents, two hot summers that ruined our food. We have been subject to starvation and people died out of hunger, in addition to the continuous brutal bombardment of everywhere.”

Speaking to reporters on Tuesday, Mr. Trump said, “I don’t want to hurt the negotiation” for a hostage exchange and a cease-fire agreement that remain under discussion. Mr. Trump’s incoming top Middle East envoy, Steven Witkoff, is expected to join those talks in Doha, Qatar, later this week.

But Mr. Trump was explicit about threatening consequences should Hamas refuse to release about 100 remaining hostages — at least a third of whom are presumed dead — who were taken from Israeli territory and have been held since the militant group led the attack on Israel.

“It will not be good for Hamas and it will not be good, frankly, for anyone,” he said.

“If the deal isn’t done before I take office, which is now going to be two weeks, all hell will break out in the Middle East,” Mr. Trump added.

His comments reverberated Wednesday across Gaza, including with some civilians who understood the threat to mean that Palestinians would be punished and not Israel if an agreement on the hostages is not reached by Jan. 20, when Mr. Trump is inaugurated.

Akram al-Satri, 47, a freelance translator from Khan Younis, in southern Gaza, said he found it strange that Mr. Trump “does not realize that Gaza has been deprived of all forms of life, and that he thinks he could add to that hell while Israel had not been spared any effort in turning the lives of Gazans into something far uglier than hell.”

“All of us who witness bombs dropping over our heads daily” were living “a reality that is more destructive and miserable than hell,” he added.

While most Gazans mainly blame Israel for the death and destruction around them, many also say they hold Hamas responsible for starting the war.

“Hamas should have reached an agreement long time ago,” said Abdul Aziz Said, 33, who is also from Deir al Balah. “They say ending the war is their priority, but do not act like this is the case. I know Israel is not offering them anything serious, but I don’t care. I want this killing to stop.”

Mr. Witkoff on Tuesday struck an optimistic tone that a deal could soon be reached. “I think that we’ve had some really great progress, and I’m really hopeful that by the inaugural we’ll have some good things to announce on behalf of the president,” he said, standing next to Mr. Trump.

Regardless of the war’s outcome, several Gazans interviewed on Wednesday said they feared a continuation of the pro-Israel policies Mr. Trump pursued in his first term, from 2017 to 2021.

In those years, the American Embassy in Israel was moved from Tel Aviv to Jerusalem, which Palestinians also claim as their capital, and the United States also recognized Israel’s sovereignty over the Golan Heights, which Israel captured from Syria in 1967. Palestinians and their allies in Arab states also worry that Mr. Trump will not stop Israel from annexing more disputed areas in the West Bank and occupying at least parts of Gaza.

But many Palestinians have fumed over the past year that the United States, under President Biden, has not done more to protect them from Israeli strikes that have leveled their cities and halted humanitarian aid deliveries.

Just this past week, the Biden administration informed Congress that it would allow American weapons producers to sell $8 billion in arms to Israel, including 500-pound bombs that can cause significant injury and death, especially in areas with little protection, like tent camps. Many of the weapons would most likely be shipped over the next two years, but some could be delivered within months.

“The engine of this entire ugly and unjust offensive is America,” said Amna Soliman, 42, a former teacher at the American International School in Gaza. “There is nothing left of Gaza.”

Forced to flee her home in Jabaliya, in northern Gaza, Ms. Soliman said that at least a half-dozen of her relatives had died and that she had lost her job since the start of the war’s “hellish reality.”

“We are already living in fear and worry and horror,” she added.

Lebanon’s deeply divided Parliament is set Thursday to try to elect a new president, potentially ending a yearslong political vacuum and ushering in a degree of stability for a country reeling from its bloodiest war in decades.

For more than two years, the tiny Mediterranean nation has been paralyzed by political gridlock and led by a weak caretaker government through a series of upheavals, including a historic economic collapse, a destructive war between Israel and the Lebanese militant group Hezbollah and the collapse of the Assad regime in neighboring Syria.

Lebanon’s election of a president would be the first step in forming a full-fledged government with a mandate to steady the country. But, despite the urgency, it remains unclear whether anyone will be elected at all.

The country’s Parliament is fractured along sectarian lines and lawmakers have failed in 12 previous votes to elect a new president since October 2022, when Michel Aoun stepped down from the office at the end of his six-year term.

The vote on Thursday could be no different. Lebanon is facing diplomatic pressure by the United States and other foreign donors who have hinged postwar financial support on the election of a president. But it is not clear that the leading candidate, Joseph Aoun, the U.S.-backed commander of the Lebanese military (and unrelated to the former president), will receive enough votes to be elected.

“This election is about Lebanon basically reaching a necessary milestone in its much-needed recovery,” said Lina Khatib, an associate fellow at Chatham House, a London-based research organization. “However, the reality is that Lebanon’s various political stakeholders are nowhere near reaching the consensus needed to agree on who will be the next president — even in this very critical period.”

“The stakes are higher than ever,” said Ms. Khatib.

The 14-month war between Israel and Hezbollah has left swaths of the country in ruin with little money to finance reconstruction. The World Bank estimates that the war has cost $8.5 billion in damages alone. Lebanon’s security situation also remains volatile, and the government that eventually takes shape will need to steer the country through a fragile 60-day cease-fire that diplomats hope will become permanent.

For over two years, Lebanon’s stalemate has paralyzed state institutions and exacerbated the country’s already crippling economic malaise. Hezbollah, the dominant political force in Lebanon, has long been considered one of the main stumbling blocks by many in the country. The group scuttled a bid last year to elect a top International Monetary Fund official as Lebanon’s president by walking out of the vote.

But analysts say that Israel’s lightning offensive against Hezbollah, which decimated the group’s leadership and shattered its image as a behemoth holding sway over the country, may provide the window of opportunity needed to break Lebanon’s political gridlock.

In the run-up to the coming election, Hezbollah appears to be showing some signs of flexibility, although it remains to be seen how the vote will play out. On Sunday, a senior official in the group, Wafiq Safa, signaled that it would not veto Mr. Aoun’s candidacy as many feared.

“They have calculated that they are still powerful, but they will have to make some concessions,” said Paul Salem, the vice president for international engagement at the Middle East Institute in Washington. “Now, they need massive and large-scale foreign aid, and they also need a legitimate state within which to exist — within which to protect themselves.”

“The first building block is to elect a president,” said Mr. Salem.

The Lebanese Parliament’s 128 members elect a president via a secret ballot, a process marred in recent years by walkouts. In the first round, a two-thirds majority is required, an outcome that analysts have called unlikely for Thursday. In subsequent rounds, however, a simple majority will suffice.

If a president is elected on Thursday, he would then appoint a prime minister, in consultation with Parliament, who will be tasked with forming the government. That is likely to be a long process, and the resulting executive body will ultimately be left with the herculean task of reviving the crisis-hit nation.

The Parliament speaker, Nabih Berri, a key Hezbollah ally, said in an interview with local media last week that he was determined to elect a president on Thursday. He has pledged to keep voting open until a candidate is agreed upon.

Mr. Berri conceded however that there was not yet any consensus on who that candidate would be, marking a departure from previous elections where stakeholders normally reach an informal agreement before the vote itself.

Amid the mounting uncertainty, Lebanon’s prime minister, Najib Mikati, who has become the beleaguered face of the country’s caretaker government, struck an optimistic tone on Wednesday.

“Today, and for the first time since the presidential vacancy, I feel happy,” he said in a statement. “God willing, tomorrow we will have a new president of the republic.”

Go ahead and recycle your Christmas tree. But please, the Belgian authorities say, don’t try to eat it.

The country’s federal food agency delivered that unusual warning this week after a suggestion from the climate-friendly city of Ghent.

If you’re trying to cut down on holiday food waste, the city recently said on an environment page of its website, why not make a “delicious spruce needle butter” with the leftover needles from your holiday tree?

“It’s a breeze,” the city’s post read. “That way your Christmas tree is not 100 percent waste.”

The city acknowledged that there could be health dangers in the bristly boughs. Yew, an evergreen, can be poisonous. Trees treated with pesticides and fire retardants are also hazardous, it said.

Ghent credited Scandinavian cooks with the idea of picking the needles, boiling and drying them, and then turning them into flavored butter. “In Scandinavia,” the city wrote, “they have been doing it for a long time.”

That turned out to be not quite true — Scandinavian food historians said it was far from a widespread tradition. And Belgium’s food agency quickly urged the public against such a gastronomic experiment.

“Christmas trees are not intended to end up in the food chain,” Hélène Bonte, an agency spokeswoman, said in an email on Wednesday.

A consumer may not know if their tree had flame retardants, she said. Pesticides are a threat, with Christmas trees “often treated intensively.” A misidentification could be deadly, as eating yew “can have serious, even fatal, consequences,” Ms. Bonte said.

And even if parts of evergreens are sometimes used in cooking, she said, not all are edible: “There is a difference between using needles from pristine nature and needles from trees specifically grown for Christmas and to be decorated at home.”

Ghent later edited the post on its website, adding information about pesticides and changing “Eat your Christmas tree” to “Scandinavians eat Christmas trees.”

The assertion surprised some of those who know the region’s food best. “We don’t eat our own Christmas trees,” said Bettina Buhl, a curator and food historian at the Green Museum in Auning, Denmark.

“I have a lot of old cookbooks published in Denmark,” she added, chuckling, “and I haven’t seen this. It’s quite a new one.”

In a response to questions, Ghent’s climate team said that it had always urged caution about consuming evergreens and that the city was focused on green policies.

“The social media post about the culinary uses of Christmas tree needles fits within a broader context of reuse, recycling, and a circular economy,” it said in an email on Wednesday.

Ghent’s suggestion is hardly the only creative approach to trying to recycle a holiday tree. Although the carcasses of many holiday evergreens are discarded with trash bags, others often find a useful, sustainable second life.

In Britain and Germany, castaway trees have been used as toys for zoo animals. In New York City, they are turned into wood chips and mulch to nourish trees in parks. Gardeners around the world replant them. Birders use them for feeders. Crafters make sachets and coasters.

But snacks do not appear to be common. And the Scandinavian connection is tenuous at best, food historians said.

“There is kind of this idea around the world that we in Scandinavia, we eat absolutely everything green,” said Nina Bauer, a Danish food historian. “We just go around in the forests and we eat everything.”

Yes, she said, many people do forage for ingredients. Some people may use evergreen materials to infuse spirits or smoke other ingredients. And high-end chefs at innovative restaurants like Noma, where diners have also been served grilled reindeer heart on a bed of fresh pine, have used evergreen trees for ingredients.

But Ms. Bauer had only heard of home cooks in Denmark eating their own holiday trees in dire times, like during World War II. Cookbooks from the time suggested that people sometimes used Christmas trees for tea during food shortages, she said.

And she was unequivocal about the region’s cuisine: “It’s not a tradition to eat your Christmas tree in Scandinavia.”

Koba Ryckewaert contributed reporting.

Christian Ulloriaq Jeppesen remembers how this all started.

In 2019, during Donald J. Trump’s first term as president, Mr. Trump floated the idea of the United States buying the island of Greenland. At the time, most people in Greenland (and Denmark, the European country that controls it) thought his suggestion was a joke.

“Everyone said, ‘Ha-ha, you can’t just buy a country, he doesn’t mean it,’” Mr. Jeppesen, a native Greenlander and a radio producer, said by telephone. “Obviously that was the wrong way to take it. Look at where we are today.”

Now Mr. Trump has doubled down on his insistence that the United States needs to annex Greenland for security reasons. And that has Greenlanders asking the same questions as everyone else, but with a lot more urgency.

Is Mr. Trump just being bombastic again, floating a fanciful annexation plan that he may know is a stretch?

Or is he serious?

Based on his comments in the last few weeks, Mr. Trump appears completely serious. Never mind that Denmark’s leadership has said the territory is not for sale, and its future must be determined by the local population.

“For purposes of national security and freedom throughout the World, the United States of America feels that the ownership and control of Greenland is an absolute necessity,” Mr. Trump wrote in late December in a social media post announcing his choice for ambassador to Denmark.

At a news conference on Tuesday, the president-elect took an even more surprising swerve. He refused to rule out using military force to get Greenland. And that same day Donald Trump, Jr., suddenly showed up on the island.

The president-elect’s son landed Tuesday afternoon in Greenland’s capital, Nuuk, toured some sights like a statue of an 18th-century Danish-Norwegian missionary and was hosted by a Danish Trump supporter. He said the reason for the trip was personal, not official, but the president-elect posted about his son and “various representatives” visiting and said “MAKE GREENLAND GREAT AGAIN.”

“This is all getting scary,” Mr. Jeppesen said.

At 836,000 square miles, Greenland is the world’s largest island, about a fourth the size of the United States. It elects two representatives to Denmark’s Parliament and 31 to its own, which is responsible for most aspects of the island’s government, though Denmark retains control in a few policy areas, including defense and elements of international affairs.

Its location and landscape make it desirable to Mr. Trump on several levels.

It is strategically positioned at the top of the world, east of Canada along the Arctic Sea, and home to a large American military base. It is loaded with mineral resources such as cobalt, copper and nickel.

And as climate change melts the ice, it is opening up new paths through the Arctic Sea, which is becoming a fiercely contested region for shipping, energy and other natural resources, as well as military maneuvering.

Greenland could also find itself in the middle of a cross-Atlantic showdown over its sovereignty. On Wednesday, the French foreign minister, Jean-Noël Barrot, said that Europe could not allow a nation to attack its sovereign borders — while adding that he did not expect the United States to invade Greenland.

The blast of attention falls on Greenland at a touchy time, with the local independence movement growing. Many Greenlanders feel increasingly resentful toward Denmark, which has played an overseer role for decades. For its size, Greenland has a tiny population and most of the 56,000 Greenlanders are Inuit, part of a group of peoples who also live in Canada and Alaska.

The Greenlandic language is completely different from Danish. Many people follow a culture and belief system quite apart from those in Western Europe. And, like Indigenous people in the United States and elsewhere, they have been oppressed for a long time.

The Greenlanders’ disaffection with Denmark was heightened two years ago with revelations about Danish doctors fitting thousands of Indigenous women and girls with intrauterine contraceptive devices in the 1960s and 1970s, often without their knowledge.

Danish officials have repeatedly said that Greenland is not for sale, though they have emphasized their desire for warm relations with the United States. Last month, Denmark’s king jumped into the fray by abruptly changing the country’s coat of arms to more prominently feature symbols of Greenland and the Faroe Islands (another territory under Denmark’s control) — a polar bear and a sheep.

Amid this debate over identity, many people are now puzzling over Mr. Trump’s intentions.

“Is it just a distraction?” asked Ulrik Pram Gad, a senior researcher at the Danish Institute for International Studies. “Or is it threat-based diplomacy?”

According to an agreement in 2009 that granted Greenland expanded self-rule, Greenlanders have the right to hold a referendum on independence. The reason it has happened yet, analysts say, is because Greenland is still heavily dependent on Denmark for many professional services — including doctors, nurses and teachers — as well as half a billion dollars a year in subsidies.

Aaja Chemnitz, one of the two representatives from Greenland in the Danish Parliament, said she worries that Mr. Trump is trying to pump up Greenland’s independence movement to further his own interests. In that case, she said, “We risk becoming a pawn in a game between Denmark and the US.”

Greenland benefits from the Danish welfare system, she said, and it would do a lot worse if it became part of the United States.

“I’ve seen the American system,” Ms. Chemnitz, who lived in New York while working for the United Nations, said in a telephone interview. “I know how harmful it can be for equality.”

Mr. Jeppesen, the radio producer, said Mr. Trump may also be misinterpreting the independent nature of Greenlanders. Greenland is not just a chunk of land. It is a nation, a story, a homeland.

“There is this enormous pride you get from being one of just 56,000,” Mr. Jeppesen said. “Greenland is amazing, it’s beautiful, it’s the most wonderful country in the world.”

“And it is a country fighting for independence,” he added. “Not a piece of property you can buy.”