Not too long ago, President Joseph R. Biden Jr. was rallying European partners to stand against the Russian invasion of Ukraine. This aligns with a sentiment echoed by top American diplomat R. Nicholas Burns, who highlighted a strategy for the United States to thrive in global power dynamics: “Treat your allies well.”

In stark contrast, President Trump has often expressed a different perspective. For years, he has shown antagonism towards Europe, perceiving alliances as competitors and burdens. His recent decision to impose controversial tariffs on American allies, notably Ukraine—while sparing Russia and North Korea—reveals his inclination to undermine a trans-Atlantic partnership that has helped maintain European peace for 80 years.

Trump’s insistence that NATO allies contribute up to 5 percent of their gross domestic product for military expenditures, along with his past ambitions for territorial claims on Denmark, a NATO member, underscores the long-lasting damage to U.S.-European relations that may never be completely mended.

“These tariffs reinforce a belief in Europe that the U.S. under Donald Trump is not just an inconsistent partner but one that cannot be relied upon at all,” stated Guntram Wolff, an economist and previous director at the German Council on Foreign Relations. “This marks a significant pivot from 80 years of postwar history, where the trans-Atlantic alliance was foundational to the Western world and the global multilateral framework.”

Although Brussels will strive to maintain essential relationships, Wolff noted, “Europe cannot single-handedly sustain the global system.”

Trump’s attempts to reshape the global landscape may inadvertently aid Russia, NATO’s primary adversary, by potentially weakening its opposition in Europe, despite falling oil prices impacting Russia as well.

“It appears there’s chaos amid the disorder,” remarked Ursula von der Leyen, the president of the European Commission, on Thursday. “There’s no clear direction through the complexities and turmoil being created as all U.S. trading partners are affected,” while “the most vulnerable citizens are suffering.”

Europeans increasingly recognize that Trump, unrestrained and further bolstered by advisors aligned with his ideology in his second term, aims to distance the U.S. from Europe. However, “the intensity, speed, aggression, and imperialistic tendencies of this administration have taken many by surprise,” commented Mark Leonard, director of the European Council on Foreign Relations.

Numerous European governments believed they could manage Trump’s demands through negotiations, such as purchasing more military equipment and liquefied natural gas—two key American exports—and enhancing burden-sharing. Recent developments illustrate the shortcomings of this approach, including the inconsistent enforcement of tariffs on Britain and the European Union and demands for Ukrainian minerals in exchange for military support over the years.

“Europe’s challenge is navigating a predatory America willing to exploit the vulnerabilities of its allies, whether through mineral deals in Ukraine or attempts to annex Greenland, or the open strategy of Trump to create divisions between Britain and the EU with varying trade agreements,” Leonard stated.

Currently, the European Union remains intact, mainly because Trump imposed the same 20 percent tariffs on all 27 member countries, including nations like Hungary, Slovakia, and Italy that have closer ideological ties. However, Washington might opt to apply differentiated tariffs on specific sectors to exert pressure on certain countries, such as Denmark, concerning Greenland.

There’s a general belief that the tariffs may lead to negotiations, as Trump’s son Eric suggested in a message on X. “I wouldn’t want to be the last country to try negotiating a trade deal with @realDonaldTrump,” he wrote. “The first to negotiate will succeed—the last will definitely lose.”

Sophia Besch, a German analyst at the Carnegie Endowment in Washington, observes two distinct messages coming from the Trump administration. “It’s uncertain if this is merely an initial offer for negotiations or if they genuinely seek to reshape the world with no interest in mending it,” she explained. “Different factions around Trump seem to be pursuing varying objectives.”

The issues concerning tariffs and security are separate yet interconnected, according to Besch and others, reflecting Trump’s readiness to exploit American power indiscriminately and carelessly against allies, their economies, and the most vulnerable populations who are likely to bear the brunt of rising inflation and higher consumer taxes.

Secretary of State Marco Rubio attempted to provide some reassurance in Brussels this past week during a NATO foreign ministers’ meeting, blending soothing comments with warnings. He denounced the “hysteria and exaggeration” from the media, asserting that Trump supports NATO and its collective defense commitments. “President Trump has made it clear that he backs NATO,” Rubio stated. “We will continue our involvement in NATO.”

But not in the way NATO currently operates.

Rubio cautioned that Trump expects European allies to take primary responsibility for their security and that of Ukraine as America shifts its focus toward Asia. “He opposes a NATO that is lacking the capabilities needed to meet the treaty obligations each member must satisfy.”

Nonetheless, the economic ramifications of the tariffs, which are anticipated to lead to inflation and slower economic growth, will complicate European allies’ efforts to enhance military spending to the NATO-recommended goal of 3.5 percent of GDP in July, let alone the 5 percent that Trump is advocating.

For Germany, a wealthy nation, the ramifications will be significant, with Finance Minister Jörg Kukies predicting a 15 percent drop in German exports to the U.S. He mentioned that Germany would still aim to negotiate better terms with Washington, while Brussels plans to respond forcefully, yet cautiously, on behalf of the bloc. Still, the German Economic Institute estimates that the costs of these tariffs for Germany could reach around 200 billion euros ($218 billion) over the next four years.

Europeans are now on the lookout for alternative markets and additional free-trade agreements, similar to those with Canada and Mexico, stated Maggie Switek, an economist and research director at the Milken Institute. “There is still potential for collaboration with the U.S. and American companies as we navigate this new reality and American approach,” she noted.

However, for Moscow, which has limited unsanctioned trade with the U.S., the tariff hit on American allies presents another advantage. Dmitri Medvedev, former President of Russia, excitedly commented on X about the damage inflicted.

Quoting an old Chinese proverb, he remarked that Russia would “sit by the river, waiting for the body of the enemy to float by. The decaying corpse of the EU economy.”

When Yoon Suk Yeol was running for president, he had the word “king” written on his palm. South Koreans dismissed — and ridiculed — it as a shamanistic ritual that reflected his desire for top government office.

But ​after his inauguration in May 2022, it didn’t take long for ​them to see an authoritarian streak in Mr. Yoon.

On short notice, he ​moved the presidential office from the graceful Blue House to a drab military building. When he turned 63 in December 2023, his security team sang songs honoring him as “a president sent from Heaven” and describing his “845,280 minutes” in office so far as “a time blessed.” Two months later, a college student who protested Mr. Yoon’s decision to cut government budgets for scientific research was gagged and dragged out by the president’s bodyguards. When journalists published what he called “fake news,” prosecutors raided their homes and newsrooms to collect evidence.

Mr. Yoon kept pushing the envelope, until he made his fatal mistake: ​On Dec. 3, he declared martial law​, threatening a deeply cherished part of South Korean life: democracy.

To​ South Koreans, democracy has never been something given​; it was fought for and won through decades of struggle against authoritarian leaders at the cost of torture, imprisonment and bloodshed​. All the major political milestones in South Korea — an end to dictatorship, the introduction of free elections, the ouster of abusive leaders — were achieved after citizens took to the streets.

So when people saw troops sent by Mr. Yoon storming the National Assembly to seize the legislature by force, their response was immediate. But unlike those who fought government repression in the ​1950s through the ​’80s, South Koreans protesting in recent months had ​democratic institutions on their side.

The current Constitution, written in 1987 after a huge pro-democracy uprising, gave the National Assembly the power to vote down martial law and ​impeach presidents. The Constitutional Court, created under ​that Constitution, got to decide whether to remove or reinstate an impeached president. And leaders democratically elected under that Constitution imprisoned those who had earlier taken power by military force​.

Younger generations, including the paratroopers Mr. Yoon sent to seize the Assembly ​in December, grew up learning of that history through box office-hit movies and novelists like the Nobel laureate Han Kang.

On Dec. 3, the troops hesitated before angry citizens blocking them with bare hands, allowing time for lawmakers, including some members of Mr. Yoon’s own party, to gather and vote to lift his martial law decree. The Assembly then impeached him, on Dec. 14.

And on Friday, the Constitutional Court’s eight justices, including those appointed by Mr. Yoon or his party, unanimously upheld that impeachment, putting an end to his military rebellion.

To one observer, these events were a victory for the democratic institutions created​ in the late 1980s. “The response to Yoon’s attempted coup d’état displayed the maturity of Korean democracy — first of all, the resilience of civil society, which reacted immediately and massively to oppose the coup, most notably with the passion of Korean youth who were not alive in the 1980s and experienced the dangers of a return to autocratic rule for the first time,” said Daniel Sneider, a former journalist who covered South Korea back then and is now a lecturer at Stanford University.

“The fact that it was a unanimous decision of the Constitutional Court, with conservative appointees joining the decision, was a very important expression of not only the clarity of the case, but also the ability to overcome ideological polarization,” Mr. Sneider said.

Mr. Yoon’s power grab also exposed the vulnerabilities of democracy in South Korea. If such a thing can happen in a nation long considered an exemplary case of democratization in Asia, scholars warned, it can happen elsewhere, too.​

Despite his removal, the deep polarization that led up to Mr. Yoon’s declaration of martial law persists. ​ ​The partisan struggle between the left and right is likely to intensify in the next two months as the country lurches toward a presidential election.

But the past four months have also shown the resilience of South Korean democracy.

​Until Mr. Yoon came along, few South Koreans thought that a return to military rule was possible in their country, a peaceful democracy known globally for its cars, smartphones and K-dramas. Many of those who joined protests calling for Mr. Yoon’s ouster in recent weeks said they had been more proud of their democracy than of their cultural exports like the boy band BTS or the Netflix hit “Squid Game.”

When Mr. Yoon hurt that pride, he picked a fight he couldn’t win. During rallies, people shared a video clip of former President Kim Dae-jung, an iconic figure in South Korea’s democratization struggle.

“Democracy is not free,” Mr. Kim said in the clip. “You must shed blood, sweat and tears for it.”

If the Constitutional Court had voted to reinstate Mr. Yoon, South Korea would have seen a “second wave of democratization movement” and “a second Gwangju,” said Cho Gab-je, a prominent South Korean journalist who has covered the nation’s political evolution since 1971, referring to the brutally suppressed uprising against martial law in the southern city of Gwangju in 1980.

“We had our share of martial law, but Yoon Suk Yeol was the first president to send armed troops into Parliament,” Mr. Cho said.

Mr. Yoon was once a hero among South Koreans. He built his national image as an uncompromising prosecutor when he helped imprison two former presidents for corruption. But he proved disastrous as a politician — unable to engage in the give and take of compromise with the opposition, which controlled the National Assembly.

He was accused of filling his presidential staff with officials too timid to speak up. He was nicknamed “Mr. 59 Minutes,” because that was how long he was said to speak during an hourlong meeting. He rarely apologized for his wife’s scandals or even for deadly disasters. He used his veto power to kill opposition bills. The opposition slashed his budgets and impeached an unprecedented number of political appointees in his government.

“A player busy playing on the field doesn’t look at the electronic scoreboard,” Mr. Yoon once said when asked about his dismal approval ratings.

Such an attitude allowed him to push unpopular efforts, such as improving ties with Japan and drastically increasing the number of doctors. But even many who sympathized with his struggle against the opposition didn’t see martial law coming.

“Koreans do not want the 1980s option, when martial law and tear gas made forcibly disappeared people painful to so many families,” said Alexis Dudden, a professor of history at the University of Connecticut. “Yoon and his advisers missed the mark of reading today’s South Korea in many obvious ways.”

On a Monday morning last fall, Ukrainian drone pilots watched what had become a familiar scene unfold on a drone’s live feed: Russian soldiers pointed their guns at two Ukrainians, who seemingly surrendered. Then, the footage showed, the Russians shot them point blank.

The video, provided by a pilot who said he had witnessed the killing on the feed, was verified by The New York Times and the Centre for Information Resilience, a nonprofit organization. It appeared to show the Ukrainian prisoners executed near the village of Novoivanovka in the Kursk region of Russia.

“There were no polite words spoken among us — we were filled with rage and an intense desire for revenge,” said the pilot, 26, who served with the 15th Mobile Border Guard and asked to be identified by his call sign of “One Two” in accordance with military protocol.

As the United States embraces Russian talking points in its push for a cease-fire in Ukraine, many Ukrainians wonder whether allegations of Russian war crimes will simply be forgotten. President Trump has indicated that he would like to re-establish ties with Russia and end the war — or at least, wind down the U.S. commitment to Ukraine made under President Joseph R. Biden Jr.

The U.S. informed European officials recently that it is withdrawing from a multinational group created to investigate allegations of war crimes against senior Russian leaders and allies responsible for launching the full-scale invasion of Ukraine in 2022. The Biden administration joined the group in 2023. The U.S. State Department has also ended funding for the tracking of tens of thousands of Ukrainian children abducted by Russia.

While both sides have been accused of committing war crimes, Russia has faced far more allegations, not only from Ukraine but also human-rights groups and the United Nations. In recent months, Ukrainian and international human-rights officials have accused Russian troops of executing Ukrainian soldiers who have surrendered instead of taking them as prisoners of war, as required under the Geneva Conventions treaties that outline how nations should treat enemy forces and civilians during armed conflict.

A recent U.N. report decried an “alarming spike” in Russian executions of Ukrainian prisoners. In December, Ukraine’s human rights ombudsman office announced that 177 Ukrainian prisoners of war had been executed on the battlefield since the beginning of the war; of those, 109 were killed in 2024 alone. Russians have killed at least 25 additional Ukrainian soldiers since then, according to Artem Starosiek, who runs Molfar, a Ukrainian consultancy that supports the war effort and analyzed videos to come up with that tally. The Times could not independently verify that count.

“This could be one of the largest campaigns of intentional P.O.W. murder in modern history,” Ukraine’s foreign minister, Andrii Sybiha, said in February.

The Russian Defense Ministry did not reply to a request for comment on the Ukrainian allegations, although the Kremlin has repeatedly denied that Russia commits war crimes in Ukraine.

Five Ukrainian drone pilots said in interviews that they had watched as drone videos showed their fellow soldiers surrendering, only to be killed. On Telegram, such videos have become commonplace. Although Russian officials have denied committing war crimes in Ukraine, some Russian soldiers appear so unconcerned about potential repercussions that they have posted their own videos of killing unarmed Ukrainians.

In past conflicts, war crimes usually happened out of sight, only to be revealed later through investigations. But drones mean that these executions can be tracked in real time: Grainy footage showed as many as 16 men, lined up and shot dead Sept. 30, after surrendering near the eastern Ukrainian town of Pokrovsk, according to the Ukrainian prosecutor general’s office. Nine Ukrainian drone operators were forced to strip to their underwear and lie face down on the ground in Kursk before being shot Oct. 10 — the footage was so clear, a mother of one man later recognized him.

Some perpetrators film the videos themselves — like one posted in January that circulated widely on social media and appeared to show the executions of six Ukrainian soldiers near Donetsk, the Ukrainian prosecutor general’s office said.

“One’s mine,” one Russian said on the video.

“Film me on camera, damn it,” another added.

The video ended with a seventh Ukrainian on the ground, his fate unclear.

Although the video’s location couldn’t be independently verified, the men killed in the video wore yellow armbands, like Ukrainian forces are known to. One soldier involved was identified by open source researchers, and later The Financial Times, as a Russian named Oleg Yakovlev.

Since the end of August, the U.N. human-rights monitoring mission in Ukraine has documented 29 encounters in which Russian soldiers killed at least 91 incapacitated Ukrainian soldiers, including the episode witnessed by One Two. Human-rights monitors analyzed videos and photos published by Ukrainian and Russian sources showing executions and dead bodies, interviewed witnesses and verified that the reported executions took place near Russian offensives, said Danielle Bell, the head of the mission.

“It’s horrible,” Ms. Bell said in an interview. “And these are just the cases that we have assessed as being credible and reliable.”

During those same six months, the United Nations documented one execution of an incapacitated Russian soldier by Ukrainian troops, Ms. Bell said.

She would not speculate on why the number of killings has increased. But in August, Ukrainian soldiers invaded Kursk, potentially sparking retaliation. Some military analysts said the Russians could be trying to intimidate potential Ukrainian recruits from joining the army and make Russian soldiers think twice before surrendering — because the Ukrainians might want revenge.

Russian soldiers captured after executing Ukrainian troops said in interrogations that they were ordered to kill them — even after telling commanders that the Ukrainians had surrendered and tossed their weapons on the ground, according to an edited video of the interrogations released recently by the Ukrainian Special Forces.

The Ukrainians apparently began to run “after hearing the command over the radio to open fire,” one captured Russian said in the video. He added: “And fire was opened on them.”

In mid-March, as Russian forces sought to retake Kursk, a photo circulated of several Ukrainian prisoners of war with their hands behind their backs. Another video, which could not be independently verified, showed the same prisoners, now dead, with three of them bleeding from the backs of their heads. The person filming used slurs to refer to them as he counted the corpses for the camera.

The orders are likely to come from the top, analysts said. The deputy head of Russia’s Security Council — Dmitri Medvedev, the former president — said that Ukrainian soldiers had no right to life or mercy after Ukraine’s Azov Brigade posted a video of a soldier shooting what appeared to be an injured Russian soldier on social media in July. “Execute, execute and execute,” Mr. Medvedev wrote on Telegram.

In October, the Washington-based Institute for the Study of War said: “Russian commanders are likely writ large condoning, encouraging, or directly ordering the execution of Ukrainian P.O.W.s.”

When drone pilots have seen the Russians pointing their weapons at the Ukrainians on video, the pilots said, they often went quiet watching their comrades get shot. Then they swore.

One commander said one scene still haunted him: A Russian soldier shot four Ukrainian soldiers lying face down in a trench near Chasiv Yar, and he could do nothing to stop it. “Without hesitation, he executed them all,” said the commander, who uses the call sign “Madara,” for a Japanese manga hero.

In another video, Russians surrounded four injured Ukrainians, forced them out of their shelter into a yard and confiscated their weapons. The Russians then took three of the soldiers to the street and shot them, said one military intelligence officer from the 110th Brigade with the call sign of “Grandfather.” It was one of three executions of Ukrainian soldiers in the Donetsk region he had watched on video feeds from drones at a command post over the past year.

“The worst part was the helplessness — we couldn’t do anything to help our men,” Grandfather said.

After seeing the Ukrainian soldiers killed on the morning of Nov. 11, One Two said commanders wanted the drone pilots to retaliate. The pilots of three units met on a video call. One Ukrainian drone tracked five Russians — the two who shot the Ukrainians, and the three who stood by — and gave a live feed of their movements into the forest. Ten other drones followed, surrounding the five Russians. And then, One Two said, the drone pilots fired their weapons and killed them.

Marc Santora, Oleksandra Mykolyshyn and Liubov Sholudko contributed reporting from Kyiv, and Alina Lobzina from London.

A Russian missile strike Friday on Kryvyi Rih, a city in central Ukraine, killed at least 16 people, including six children, and wounded more than 50, local officials said. It was the latest in a series of Russian attacks on urban centers in recent days, despite ongoing cease-fire talks, that have caused significant civilian casualties.

Serhii Lysak, the head of the Dnipropetrovsk region, which includes Kryvyi Rih, said on social media that the missile struck a residential neighborhood, with a playground nearby. Other officials warned the death toll could rise as rescuers continued to search the rubble for victims.

Russia’s defense ministry acknowledged the missile strike on Kryvyi Rih on Friday. It claimed that the missile had targeted a restaurant where Ukrainian commanders and Western military instructors were meeting, killing a total of 85 servicemen.

Moscow has long claimed that it only aims at military targets, although direct Russian strikes on civilian areas and facilities have often been documented by journalists and independent organizations.

Friday’s attack came as Russia appeared to have ramped up its attacks on civilian areas in recent weeks. Kryvyi Rih, the hometown of President Volodymyr Zelensky, was also struck on Wednesday in an attack that killed four people. On Thursday, a Russian drone attack on the eastern city of Kharkiv also killed four people, according to the city’s mayor.

The number of civilian casualties could not be independently verified.

The unusually high toll on Friday comes as both countries have engaged in cease-fire negotiations partly aimed at reducing the war’s impact on civilians. Ukraine and Russia have so far committed to halting attacks on energy infrastructure and in the Black Sea, but these truces have yet to be implemented, with both sides accusing each other of violations.

The start of cease-fire negotiations in mid-February raised hopes that the fighting would ease, as both sides aimed to demonstrate to the United States, the mediator, that they were willing to engage and reach an accord. But the war has raged on unabated.

A series of Ukrainian cities, many of them far from the front lines, have suffered deadly strikes. A large Russian drone attack on Kyiv, the capital, killed three civilians late last month, hours before U.S.-mediated talks to discuss a partial cease-fire began in Saudi Arabia.

Ukraine, meanwhile, has also continued its assaults, including by launching drones inside Russia.

In a post on social media, Mr. Zelensky said Friday’s attack was proof that “Russia does not want a cease-fire, and we see it.”

Mr. Zelensky echoed a widespread sentiment in Ukraine that the Kremlin has engaged in cease-fire negotiations as an empty show of good will to curry favor with the White House, but has no intention of halting the fighting.

Ukraine had initially agreed to a unconditional 30-day cease-fire to halt all fighting. But Russia rejected the proposal and instead suggested a more limited truce focused on the Black Sea and energy infrastructure, which Ukraine accepted last week.

Since then, both sides have accused each other of attacking their respective energy systems. Moscow has demanded the lifting of economic sanctions before a truce at sea takes effect, effectively freezing its implementation.

The Trump administration appears to have grown tired of the drawn-out cease-fire negotiations.

U.S. Secretary of State Marco Rubio told reporters in Brussels on Friday that Russia was running out of time to convince the Trump administration that it was serious about a peace deal with Ukraine.

“We’re testing to see if the Russians are interested in peace,” Mr. Rubio added. “Their actions — not their words, their actions — will determine whether they’re serious or not, and we intend to find that out sooner rather than later.”

Images of the aftermath of Friday’s attack, posted by Mr. Zelensky, showed bodies sprawled on the grass of what appeared to be a playground, some covered with rescue blankets. Around the playground, tree tops had been torn off and building windows shattered by the blast.

Olena Zelenska, Mr. Zelensky’s wife, posted a lengthy and emotional message on social media after the attack, pointing to the series of recent Russian strikes that killed civilians.

“‘What’s going on in Ukraine? Is it quieter now? We heard something about a cease-fire,’ foreigners ask, far away from the war,” she wrote.

“We heard ‘something’ too, of course,” she continued. “The sounds of alarm. The approach of missiles and drones. The screams and the crying. We hear them even now. They are with us forever.”