For Yoon Suk Yeol, the unpopular president of South Korea, things appeared to worsen with each passing day. Thousands of doctors had been on strike for almost a year to resist his health care reforms. The opposition in Parliament repeatedly pushed for investigations into his wife, as well as the impeachment of his cabinet members, accusing them of corruption and abuse of power. And the lawmakers blocked many of Mr. Yoon’s bills and political appointments.

On Tuesday night, Mr. Yoon took a desperate measure, his boldest political gamble, which he said was driven by frustration and crisis. In a surprise, nationally televised address, he declared martial law, the first such decree in the country in decades. The move banned all political activities, civil gatherings and “fake news” in what he called an attempt to save his country from “pro-North Korean” and “anti-state forces.”

But it ended almost as abruptly as it had started.

Thousands of citizens took to the streets, chanting “Impeach Yoon Suk Yeol!” Opposition lawmakers climbed the walls into the National Assembly as citizens pushed​ back police. Parliamentary aides used furniture and fire extinguishers to prevent armed paratroopers from entering the Assembly’s main hall. Inside, lawmakers who included members of Mr. Yoon’s own People Power Party voted unanimously to strike down his martial law. Six hours after declaring it, Mr. Yoon appeared on television again, this time to retract his decision.

It was the shortest-lived and most bizarre martial law in ​the history of South Korea, which had had its share of military coups and periods of martial law before it became a vibrant democracy after the military dictatorship that ended in the late 1980s.

In the end, driven by his own impulsiveness and surrounded by a small group of insiders, who seldom said no to a leader known for angry outbursts, Mr. Yoon shot his own foot,​ according to a former aide and political analysts.​ Now his political future ​is on the chopping block​, thrusting one of the United States’ most important allies in Asia into political upheaval and leaving many South Koreans in a state of shock.

On Wednesday, the opposition parties, which control the legislature, submitted an impeachment bill after Mr. Yoon did not respond to their demand that he resign because his martial law declaration had been unconstitutional. An editorial in the leading conservative daily Chosun Ilbo, which has often been friendly toward Mr. Yoon, now accused him of “insulting” South Korean democracy. South Koreans have not seen their leader declare martial law since the military dictator Chun Doo-hwan used it to seize power in 1979​ and later massacre pro-democracy students.

“The best option Yoon has now is to resign,” said Sung Deuk Hahm, a professor of political science at Kyonggi University, west of Seoul. “As tragic as it may seem, what happened overnight showed the resilience and durability of South Korean democracy.”

Mr. Yoon did not immediately respond to the opposition’s demand. On Wednesday, all senior aides to Mr. Yoon tendered their resignations to Mr. Yoon, leaving him more isolated than ever. Analysts were skeptical about ​Mr. Yoon’s political future.

“I don’t think he can finish his five-year term,” said Kang Won-taek, a political scientist at Seoul National University.

On Wednesday, Mr. Yoon’s office said the president’s decision to declare martial law was an inevitable measure in accordance with the constitution to “restore and normalize the state of affairs” from political paralysis.

Mr. Yoon has grown increasingly despondent in recent months, particularly over escalating scandals surrounding him and his wife and the relentless political pressure from the opposition, said Mr. Hahm, who has known Mr. Yoon since before his election.​

“Things have become too much for him,” ​Mr. Hahm said. “He became mentally unstable under political pressure.”

Mr. Yoon was surrounded by a handful of aides, including former military generals, who were not used to second-guessing their boss’s decision, said a former presidential aide to Mr. Yoon who agreed to discuss the president’s leadership style on the condition they not be identified. That small circle raised questions about how thoroughly Mr. Yoon prepared for martial law.

The former presidential aide said that as soon as he heard the declaration of martial law, he called contacts in Mr. Yoon’s office and other branches of the government. But none of them had advance knowledge of what was coming, he said.

Even top leaders of Mr. Yoon’s party said they learned of the declaration through the news media. Kim Byung-joo, an opposition lawmaker and former general, told MBC Radio on Wednesday that when he called army generals near the border with North Korea, none of them knew what was happening. Paratroopers mobilized to occupy the National Assembly showed none of the decisiveness and brutality their predecessors used in the 1980 crackdown on pro-democracy activists, when as many as hundreds were killed in the southern city of Gwangju during Mr. Chun’s period of martial law. On Wednesday, the soldiers peacefully retreated after the Assembly voted to repeal Mr. Yoon’s action.

Some opposition lawmakers and social media commentators speculated that Mr. Yoon might be preparing for martial law when he appointed Kim Yong-hyun, his chief bodyguard and former army general, as his defense minister in September. ​But members of his government called the idea a conspiracy theory, and not many people took it seriously.

Before he was catapulted into the presidential race in 2022, Mr. Yoon was a political neophyte. He was a star prosecutor who wielded the law to help imprison two former presidents, and was used to a strictly top-down culture.

He won the election by a razor-thin margin, thanks largely to the public’s discontent with his predecessor, Moon Jae-in. But, from the start, he laid out big ambitions, seemingly staking his claim for a legacy as a change maker in a gridlocked political system.

Mr. Yoon put South Korea back on a path toward embracing more nuclear power, mended ties with Japan and expanded military cooperation with the United States and Japan as he took a harder line against North Korea.

But little of his domestic agenda has worked out. His opponents won even greater control in the National Assembly in parliamentary elections this year. His government was accused of using prosecutors and criminal investigations to intimidate opposition leaders and crack down on news media he accused of spreading “fake news​.” ​His approval rating plummeted to around 20 percent, as he repeatedly vetoed the opposition’s demands for independent investigations into allegations against his wife, Kim Keon Hee. The opposition also imposed large changes on his budget proposals for next year.

Mr. Yoon was often called a “tribal leader” by political analysts for his penchant for appointing loyal friends among former prosecutors and fellow high school alumni to key military and government posts.​

One of ​them was Han Dong-hoon, Mr. Yoon’s loyal lieutenant when he was prosecutor general. As president, Mr. Yoon appointed Mr. Han as justice minister and later helped make him the head of his governing party. But they fell out over differences in how to handle allegations against the first lady.

They ​grew to dislike each other so much ​that Mr. Yoon considered Mr. Han a betrayer, ​according to former aides and local media.

“He must have felt that he was surrounded by enemies and that he must make a bold decision,” said Ahn Byong-jin, a political scientist at Kyung Hee University in Seoul. “But it’s mind-boggling that he didn’t know how it would be received by the National Assembly and the people.”

Mr. Hahm, the professor, said Mr. Yoon was an impulsive man surrounded by “sycophantic aides​.” When he met the president after his party’s crushing defeat in parliamentary elections in April, he was surprised that Mr. Yoon had become more “obstinate and talkative,” Mr. Hahm said.

Mr. Yoon appeared to live with conflicting emotions, Mr. Hahm said. On one hand, he brimmed with optimism that things would work out almost miraculously, as they had in his previous career. On the other, he feared that he would end up a failed president with no positive legacy to speak of — a result he seemingly ensured when he moved to use the military against his opponents Tuesday night.

“I think those two emotions have combined to lead him to his decision,” he said.

In Ukraine, they are known as the “Executed Renaissance,” pioneering literary artists whose lives were snuffed out by Stalin’s brutal purges in the 1930s.

Living together in an apartment building and embracing experimental art forms, these writers, poets and directors spearheaded a flourishing of Ukrainian culture and identity about a century ago.

But that golden age was short-lived. The Soviet regime soon began to surveil, arrest and ultimately execute about half of the writers in an effort to stifle Ukrainian culture. For decades, their works were banned and their legacy nearly erased.

Until now.

In the face of Russia’s invasion, the story of the Executed Renaissance has been given new resonance as many Ukrainians seek to reclaim their cultural heritage. The lives of the writers are being told in a musical, a feature movie and a memoir. There is even a fashion line themed around them, with sweatshirts riddled with bullet holes to symbolize their killings.

“It’s a big trend,” said Yaryna Tsymbal, the author of “Our Twenties,” an anthology of Ukrainian literature from the 1920s. She said the demand for projects about the artists came “from everywhere: publishing houses, magazines, theaters.”

For months, his country was battered by escalating Israeli bombardment, while behind the scenes, the United States and Gulf countries courted him diplomatically. It was a secretive, two-pronged approach meant to pressure President Bashar al-Assad of Syria to abandon his most important regional alliance with Hezbollah and Iran.

The overtures to Mr. al-Assad were the product of what Israel and its allies saw as a rare but risky opportunity — with Iran’s regional network fracturing under Israeli attack, they hoped to force Iran’s most important partner out of the alliance, according to former U.S. officials, two European diplomats and four Israeli officials who spoke on the condition of anonymity because of the sensitivity of the subject.

Now, those regional ambitions may be derailed by a far smaller and long-discounted force: Resurgent rebels have launched a surprisingly successful attack in Syria, exploiting in part the strain Israel has put on the alliance that helped Mr. al-Assad maintain power through more than a decade of uprising and civil war. In a matter of days, the rebels seized most of the country’s large city of Aleppo, and challenged Mr. al-Assad’s grip on the country’s northwest.

Despite his traditional partners being so weakened, regional experts and diplomats expect that Mr. al-Assad will now be even more reluctant to abandon Iran and its allies, who are still his best bet for fighting, yet again, for his regime’s survival.

Syria is at the center of today’s regional power struggles because of the critical land corridor it provides for Iran to Hezbollah, Tehran’s most important regional ally, in Lebanon. Severing this pipeline for weapons, supplies and people is critical to Israel — and defending it is just as critical to Iran.

Israel, with the support of the United States, was eager to take advantage of its campaign against Hamas after the Oct. 7, 2023, attacks. After Israel killed key leaders of Hezbollah and Hamas and depleted their weapons stockpiles, there were signs that Israel’s approach was working. Iran’s bellicose rhetoric toward the United States and Israel had given way to signals that it wanted less confrontation. Russia, another key ally of Mr. al-Assad’s, has been ensnared in Ukraine, emboldening Israel and U.S. regional allies to pressure Moscow and Mr. al-Assad into rethinking the alliance.

But the attack on Aleppo has jolted Iran and Russia into issuing new vows to come to Mr. al-Assad’s aid, suggesting that the alliance will defy the attempts to unravel it.

Andrew Tabler, a senior fellow at the Washington Institute and a former White House and State Department official, said the long-term regional efforts, which aimed to gradually compel Mr. al-Assad to shift, now look unlikely without his showing a willingness to “make a hard break with Iran.”

“How could he do that under the current circumstances?” he said. “Iran is now more essential to his staying in power than perhaps ever.”

Before the rebel advance, Israel had for weeks been escalating its attacks on Syria, striking everywhere from the capital to the ancient desert city of Palmyra, in what it says were operations targeting Iran, Hezbollah and their allies. Israeli commandos have raided secret military sites, the aim of which, one of the senior Israeli officials said, was to demonstrate that Israel would not tolerate any further weapons smuggling from Syria to Lebanon.

But that approach had a major flaw, analysts said: Even with its intensified operations, Israel had not managed to shut down the supply line from Iran to Hezbollah, involving hundreds of miles of porous borders, secret tunnels, smuggling rings and militant groups.

“There is no way just by carrying out airstrikes that they can defeat the Iranians in Syria,” said Haid Haid, a fellow at Chatham House in London who focuses on Syria. “The Israelis can inflict damage. They can reduce the flows. They can make it more difficult. But they cannot stop it completely, and they know that.”

That is why Israel’s military push has been underpinned by diplomatic efforts, mediated by Washington and Gulf Arab leaders, who are also eager to undermine Iranian influence in the region. Eight current and former Western and regional diplomats and Israeli officials shared with The New York Times details of different proposals made to Syria.

Mediators focused on promises of Gulf economic aid, they said, and the withdrawal of hundreds of U.S. troops deployed in northeastern Syria since 2014. They also floated plans to lift or reduce crippling U.S. sanctions against the Syrian regime — though withdrawing some sanctions requires a vote in U.S. Congress, and previous efforts to persuade senators to abandon the bipartisan legislation have failed.

“They have been making offers to Assad: Your ally Iran is getting weak, so let us in,” said Malik al-Abdeh, the founder of the consultancy Conflict Media Solutions and a longtime mediator in Syria. “But getting Assad to do that would require a much more dramatic shift in the balance of power.”

Efforts by the Gulf nations, particularly the United Arab Emirates, to try to lure Mr. al-Assad away from his regional allies are not new, officials said. A European, a regional and a former U.S. official told The Times that the previously established back channels for negotiations, hosted or mediated by Gulf officials, in particular the United Arab Emirates, are being utilized again.

But regional diplomats and experts warn that continued Israeli bombardment to try to lure Mr. al-Assad away from Iran at a time when he faces a renewed insurgency risks escalating violence that could unleash chaos with fallout beyond Syria.

Syria is now territorially divided among Mr. al-Assad, Islamist militants, U.S.-backed Kurdish groups and Turkish-backed rebels. Unsettling that precarious equilibrium could embolden other groups to attack al-Assad-held territory, potentially rekindling the civil war and causing a new outpouring of refugees or a resurgence of jihadist groups, similar to the rise of the Islamic State in 2014.

Israel needs a strong central government in Syria to carry out its plan to pressure Mr. al-Assad and cut off supply routes from Iran to Lebanon, two of the Israeli officials said. Israel and the United States are continuing their efforts, but the chances of success for this plan appear to have diminished even further, they said.

Israel had also been pressing for assistance from Moscow, arguably Mr. al-Assad’s most important military ally. He is in turn critical to Russia because of the warm water port he allows it to operate on Syria’s coast.

Moscow had made gestures about limiting Iranian influence, the two European diplomats said, by increasing patrols in southern Syria near the Israeli border, ostensibly blocking Iranian-backed groups from operating there. Most regional experts saw this as futile: Iranian-aligned forces still operate along Syria’s southern border..

Russia and Iran have a complicated relationship, competing for resources in Syria. But Russia is also dependent on Iran for cheap drone technology for its war in Ukraine and for help with military operations to support Mr. al-Assad, a role ever more critical as he comes under renewed rebel pressure.

“Russia knows that without Iranian boots on the ground, it would have to be theirs,” said Mr. al-Abdeh.

Mr. al-Assad is not only dependent on Iran and Hezbollah militarily, but also financially.

The oil Iran provides Syria in defiance of international sanctions not only supports the formal economy but also the black market networks that many regime figures profit from, regional experts said. Many military leaders and militias aligned with Mr. al-Assad are deeply involved in the lucrative production of the stimulant Captagon, a booming drug trade facilitated by networks linked to Hezbollah and Iranian-backed groups.

These illicit and secretive networks, diplomats said, make it hard for Gulf Arab states to simply entice Mr. al-Assad’s government with aid and reconstruction funds.

Even if he still wanted to try to disentangle these patronage and security networks, Mr. al-Assad may be unable to, said Emile Hokayem, the director for regional security at the International Institute for Strategic Studies.

“He probably doesn’t know that well who in his first and second circle is in the pockets of Iran — or the Russians,” he said. “That’s one thing we don’t fully understand, which is Iran’s coercive power within these structures. Iran is still embedded in a lot of security agencies and militias, and it can threaten the edifice from within.”

Aaron Boxerman contributed reporting from Jerusalem.

The offer was as enticing as it was unexpected for a relative political newcomer. Three years ago, Prime Minister Justin Trudeau asked Mélanie Joly to become foreign affairs minister, among the most prestigious and highest profile portfolios in Canada’s cabinet.

But Ms. Joly, who at the time held a significantly less influential ministerial role, turned him down flat.

Her refusal wasn’t because of the fact that she lacked foreign policy experience. She said no because she feared that the travel involved in the globe-trotting job would force her to abandon her yearslong quest to conceive a child through in vitro fertilization.

But Canada’s leader refused to give up.

Mr. Trudeau offered to make whatever arrangements necessary to maintain Ms. Joly’s treatment anywhere in the world. “‘If you become pregnant,’” she remembers him telling her, “‘it would be a fantastic message you would send to the world.’”

After consulting her husband, parents and siblings, Ms. Joly relented, becoming Canada’s top diplomat.

Like her counterparts around the world, Ms. Joly has since had to grapple with Russia’s invasion of Ukraine and the Israel-Gaza conflict.

Then there are the diplomatic stresses specific to Canada.

She is still trying to heal a rift with China that developed after that country jailed two Canadians in apparent retaliation for Canada’s arrest of a Chinese executive at the request of the United States.

Now she’s at the center of Canada’s greatest diplomatic crisis in recent years: accusations that the government of India and its diplomats worked with criminal gangs to intimidate and even murder Canadian citizens who are supporters of a separate Sikh state.

And the return of President-elect Donald J. Trump, and his threat to impose large tariffs on Canadian goods, poses so many diplomatic, economic and immigration issues that Mr. Trudeau has revived a cabinet committee on U.S. relations that includes Ms. Joly.

Her handling of all these challenges has brought Ms. Joly, 45, both praise and criticism.

But what is less open to debate: The high-profile job has placed her among the likely successors to Mr. Trudeau, whose political popularity has cratered over the past year.

Like all members of Mr. Trudeau’s cabinet, Ms. Joly is publicly supportive of the prime minister. But other members of the Liberal Party have urged him to resign to let a new voice lead the party into elections that must be held by next October.

Mr. Trudeau has rebuffed these calls to quit as party leader, which would also mean resigning as prime minister. But speculation in the Canadian news media about who his successor will be — whenever that time comes — invariably includes Ms. Joly.

“I’ve known Trudeau for a long, long time, and he has my hundred percent support — period,” she said. “But the middle class is hurting, and Canadians expect us to be there for them.”

She added: “We need to be able to adapt.”

After graduating from law school, Ms. Joly landed a position at Stikeman Elliott, one of Canada’s largest law firms.

“I didn’t like it — period,” she said. “I was a litigator and I love, I love, being able to debate. But at the end of the day, I was debating for money and I wanted to have more impact on my community.”

Before quitting the law, Ms. Joly submitted a letter in 2007 to La Presse, a Montreal newspaper, condemning a wave of anti-immigrant sentiment then sweeping much of Quebec. Immigration, she wrote, “is not just a necessity, but an enrichment.”

After a brief stint in television journalism, Ms. Joly moved into public relations. Among her clients was a scion of the Bronfman family, which made its fortune with Seagram’s whisky, during the heir’s unsuccessful bid to buy the Montreal Canadiens hockey team.

That sort of work raised Ms. Joly’s profile to the point where she launched a bid in 2013 to become mayor of Montreal, her hometown, running on an anti-corruption platform. Despite zero political experience, she finished second.

Through her fund-raising for the arts, Ms. Joly met Alexandre Trudeau, a filmmaker, author and brother of Justin Trudeau. He invited her into a group that led his brother’s successful bid for the leadership of the Liberals in 2013.

Two years later, Ms. Joly was not only a newly minted member of Parliament, representing a district in Montreal, but also part of Mr. Trudeau’s first, gender-balanced cabinet. Her open and friendly manner fit with the new prime minister’s promise of a “sunny ways” approach to governing.

Her first position was also high profile: the minister responsible for cultural matters. But a deal she struck with Netflix to invest in Canadian film productions created outrage in Quebec because it included no commitments to French language programming. She was soon demoted to tourism minister and then held a series of other minor posts.

Ms. Joly had studied international law as a graduate student at Oxford but never practiced it. If she had been harboring an interest in global affairs as a lawmaker, she never made it public and was largely focused on domestic policy issues before accepting the foreign minister role.

Within a month of her promotion, there was another life-changing event: She was pregnant.

“So the two main dreams of my life were happening at the same time,” Ms. Joly said in her modest walk-up apartment in Montreal’s bohemian Plateau neighborhood. “When you’re pregnant, you feel empowered. I felt empowered.”

But before she even had much time to settle into her demanding new job, she suffered a miscarriage. She has continued with her I.V.F. treatments since, including meeting with physicians as she travels the world.

“There is a second room that is still under construction that could be ready for a baby,” she said, gesturing to the other side of the apartment, before briefly losing her composure and excusing herself for a moment.

From her first day on the job, Ms. Joly faced the same fundamental issue that has confronted all her predecessors: defining a place in the world for a middle-sized power with a relatively large economy, huge landmass and relatively small military.

Ms. Joly’s answer is what she calls “pragmatic diplomacy,” which includes the idea that “we need to work with countries that we don’t see eye-to-eye with.”

Ms. Joly recently said that the government’s previous experience with Mr. Trump, as well as its efforts to develop relationships with members of his new administration, have made it something of a model of how to deal with his White House.

“If there’s a country in the world that understands the United States, it’s Canada,” Ms. Joly said this month at the Asia-Pacific Economic Cooperation summit in Peru. “That’s why there are so many delegations, so many countries, coming to see us.”

Under Ms. Joly, Canada did try to work with India, if unsuccessfully, before ultimately expelling six diplomats.

While relations with China have slid further following intelligence leaks indicating that it attempted to interfere in Canadian elections, Ms. Joly went to Beijing in July to meet her Chinese counterpart, Wang Yi.

“There’s that movement — which I an profoundly against — which is if you don’t engage with countries, you’re sending a message that you’re strong,” she said. “I think that to be strong is to be able to have the tough conversations.”

Not everyone agrees.

Lawrence Herman, a fellow with the C.D. Howe Institute, a policy group, wrote in The Globe and Mail newspaper that the trip to Beijing was “one of the most ill-conceived and self-defeating Canadian foreign-policy initiatives in recent memory.” By traveling to China, he wrote, Ms. Joly “makes Canada look like a supplicant.”

But Ms. Joly insists diplomacy is no different than any other part of life.

“For me, international relations is, first, about human connections and, second, it’s about being able to understand the different interests at stake,” she said. “What I’ve learned through my professional life is how to look at very complex situations and make them simple for people.”

While there are already skeptical voices about the prospects of her still-hypothetical leadership campaign, Ms. Joly has encountered similar doubts before.

“It’s been the story of my life, you know, being underestimated,” she said.