Ever since the Korean War was halted in an uneasy truce in 1953, South Koreans have lived under an American promise to defend their country, if necessary, with nuclear weapons. President Biden emphatically reiterated that commitment last year, vowing that any nuclear attack by North Korea would lead to the destruction of its government.

But decades of American assurances have failed to deter North Korea from building a nuclear arsenal and then expanding it. Led by Kim Jong-un, North Korea has also become more provocative, testing missiles powerful enough to reach the United States. And it has rattled South Korea by reviving a Cold War-era defense agreement with Russia, another nuclear-armed state.

The South has long considered it a taboo to pursue atomic weapons in defiance of Washington’s nonproliferation policy. But jitters about security here have been intensified by the possible re-election of former President Donald J. Trump, whose commitment to the alliance between Washington and Seoul appears to be shaky at best.

Now, a growing majority of South Koreans say their country needs its own nuclear weapons instead of relying on the United States for protection. The idea, although still disavowed by the South Korean government, is increasingly becoming part of mainstream political debate.

Polls show that many South Koreans say they can no longer trust the American nuclear umbrella to guard them from North Korea. They doubt that Washington would come to their aid in the event of a conflict with North Korea now that Pyongyang is racing to develop the ability to attack American cities with nuclear warheads.

“We cannot expect — and should not ask — the American president to use his nuclear weapons to defend an ally at the risk of sacrificing his own people,” said Cheong Seong-chang, who leads a group of 50 analysts pushing for a domestic nuclear arsenal in South Korea. “We must defend ourselves with our own.”

South Korea abandoned its nuclear weapons program in the 1970s, as Washington pushed nonproliferation, and chose to rely on the United States to defend it against the North. Tens of thousands of American troops have been garrisoned for decades in the South, which for many years also hosted U.S. nuclear weapons. Washington withdrew those arms in 1991, hoping the disarmament would incentivize Pyongyang to stop pursuing its own nuclear weapons.

For a while, Washington had two important partners in that effort: China and Russia. But in recent years, it has found itself increasingly at odds with both of those countries on issues such as trade tariffs and the war in Ukraine. Now, neither cooperates in American-led efforts to roll back North Korea’s nuclear ambitions.

Mr. Kim’s regime has tested both atomic weapons and intercontinental ballistic missiles. It is developing technology to deliver multiple nuclear warheads with a single missile. It is also escalating its threat to target South Korea with a fleet of nuclear-capable, short-range ballistic missiles, which Mr. Kim said this month he would deploy near the border with South Korea.

In June, the Stockholm International Peace Research Institute estimated that North Korea had built roughly 50 nuclear warheads and had enough fissile material to build another 40 or so. It was also focusing on tactical nuclear weapons, which have a smaller payload.

“There is a growing concern that North Korea might intend to use these weapons very early in a conflict,” wrote Matt Korda, a researcher at the institute.

It was fears such as these that President Yoon Suk Yeol of South Korea tried to address when he met Mr. Biden at the White House last year. The two leaders deepened their alliance and signed the Washington Declaration to show that the American defense commitment was ironclad. Last month, they reaffirmed that any nuclear attack by North Korea would be met with “a swift, overwhelming and decisive response.”

“For the first time, it has been written down in a document that American nuclear assets will be tasked with deterring and countering North Korea’s nuclear force,” said Kim Tae-hyo, Mr. Yoon’s deputy national security adviser.

But that has done little to tamp down misgivings in South Korea about the American nuclear umbrella, which also covers Japan.

A poll in February showed that the percentage of respondents who said Washington would defend their country with nuclear weapons even though North Korea could attack the mainland United States with nuclear missiles had dropped to 39 percent from 51 percent last year. Another survey, which has been conducted annually for a decade, found a historical shift. Asked to choose between having nuclear weapons or U.S. troops on their soil, more South Koreans, for the first time, picked the former.

Other surveys have found as many as 70 percent of all South Koreans supporting an independent nuclear arsenal. It has become increasingly common for conservative politicians and private and government analysts to support or discuss the idea, especially after Russia’s invasion of Ukraine highlighted the extent to which a nuclear-armed power could get away with invading a nonnuclear neighbor.

“The call for nuclear weapons will be anything but short-lived because ‘going nuclear’ sounds sexy as a slogan,” said Lee Byong-chul, who has studied nuclear nonproliferation at the Institute for Far Eastern Studies in Seoul. “But there is a huge gulf between high public support and a lack of technical capabilities and political intention to build nuclear weapons.”

South Korea has neither facilities to produce fuel for nuclear bombs nor the technical know-how to design nuclear weapons. And while Mr. Yoon has been more antagonistic toward the North than his recent predecessors and briefly warmed to the idea of going nuclear, there is little political will in the South to pursue atomic weapons.

Strengthening reconnaissance and missile abilities, analysts say, would serve South Korea better and give it the ability to launch pre-emptive strikes against the North.

Building nuclear weapons would be “redundant” and “would not make South Korea any safer,” said Chun Yung-woo, a former national security adviser, “as long as the South Korea-U.S. alliance is alive and well.”

But the future of that alliance is likely to be volatile if Mr. Trump — who tried to negotiate with Mr. Kim face to face — is re-elected in November.

“It’s nice to get along when somebody has a lot of nuclear weapons,” Mr. Trump said of Mr. Kim when he accepted his party’s presidential nomination last month. “I think he misses me, if you want to know the truth.”

For supporters of a domestic nuclear force in South Korea, Mr. Trump’s potential return to power could be a good thing. He once said he would be open to allowing Japan and South Korea to build their own nuclear arsenals rather than depend on the American nuclear umbrella.

“It could open a window of opportunity,” said Mr. Cheong, the pro-nuclear analyst.

High-level talks to halt the war in Gaza ended without an immediate breakthrough on Friday, but the United States, Egypt and Qatar said the negotiations would continue next week as mediators raced to secure a truce that they hope will avert a wider regional conflagration.

The announcement came after top American, Israeli, Egyptian and Qatari officials ended two days of talks in Doha, the Qatari capital, aimed at trying to resolve remaining disagreements between Israel and Hamas. U.S. and regional officials hope that movement in the negotiations will blunt or stop a widely anticipated Iranian-led retaliation for the killing of senior leaders of Hamas and Hezbollah, militant groups backed by Iran.

U.S., Iranian and Israeli officials said on Friday said that Iran had decided to delay its reprisal against Israel to allow the mediators to continue working toward a cease-fire in Gaza.

After the first day of talks ended on Thursday night, Mohammed bin Abdulrahman Al Thani, the Qatari prime minister, called the acting Iranian foreign minister, Ali Bagheri Kani, to encourage Iran to refrain from any escalation given the cease-fire talks in Doha, according to two Iranian officials and three other officials familiar with the call who spoke on condition of anonymity because they were not authorized to speak publicly.

Mr. Al Thani spoke with Mr. Bagheri Kani again on Friday, and both officials “stressed the need for calm and de-escalation in the region,” according to the Qatari Foreign Ministry. Mr. Bagheri Kani said in a statement that the Qatari prime minister had described the cease-fire negotiations on Thursday as being at a “sensitive” phase.

On Friday, Egypt, Qatar and the United States said in a joint statement that the mediators had presented Israel and Hamas with “a bridging proposal” consistent with the terms laid out by President Biden on May 31 and later endorsed by the U.N. Security Council.

“This proposal builds on areas of agreement over the past week, and bridges remaining gaps in the manner that allows for a swift implementation of the deal,” the statement said. All three governments characterized the talks in Qatar as “serious, constructive and conducted in a positive atmosphere.”

Speaking at the White House on Friday, Mr. Biden said: “We are closer than we have ever been. I don’t want to jinx anything.” He added: “We are not there yet. But it’s much, much closer than it was three days ago.”

Mr. Biden also spoke with the emir of Qatar and, separately, with President Abdel Fattah Al-Sisi of Egypt to review the progress made in Doha on the Gaza cease-fire and hostage-release deal.

Senior officials will convene next week in the Egyptian capital, Cairo, in the hopes of finalizing the deal based on the terms laid out in Qatar, the joint statement said. In the meantime, lower-ranking officials will continue to hammer out technical details on how the cease-fire proposal would be carried out, Egypt, Qatar and the United States said.

Details of the bridging proposal were not immediately known. But Mr. Biden previously described a three-phase plan that would free the remaining hostages seized during the Oct. 7 Hamas-led attack on Israel in exchange for Palestinian prisoners held in Israel, and would ultimately lead to the “cessation of hostilities permanently” and the rebuilding of Gaza.

In a statement on Friday, Prime Minister Benjamin Netanyahu of Israel continued to blame Hamas for blocking a deal. But he has also stiffened Israel’s terms for an agreement in recent weeks, including calling for Israeli troops to remain on the Gazan side of the territory’s border with Egypt to prevent Hamas from rearming itself.

“Israel appreciates the efforts of the U.S. and the mediators to dissuade Hamas from refusing a hostage-release deal,” Mr. Netanyahu said. “Israel’s fundamental principles are well known to the mediators and the U.S.” He added that Israel hoped that the pressure would lead Hamas to accept an Israeli proposal outlined in May.

There was no immediate comment from Israeli or Hamas officials on whether they would participate in the upcoming talks in Cairo.

Hamas officials, who have accused Mr. Netanyahu of bargaining in bad faith, did not participate directly in the talks in Doha. But two Hamas officials said on Friday that mediators had updated the group on the negotiations. The officials said, without elaborating, that the current proposal did not conform to terms the group had agreed to last month.

Ghazi Hamad, a senior Hamas official, said in a televised interview that “none of the points of contention” had been resolved in Doha. “Israel either added new conditions, or asked for new wordings or complicated matters,” Mr. Hamad told Al Mayadeen, a Lebanese broadcaster seen as closely aligned with Iran and its allies. “There was no advancement.”

The push for a cease-fire has taken on heightened significance as the region braces for Iran to retaliate after an explosion in its capital, Tehran — widely attributed to Israel — killed Ismail Haniyeh, Hamas’s political leader. Hezbollah, Iran’s armed ally in Lebanon, also has promised to avenge the death hours earlier of a senior commander, Fuad Shukr, in an Israeli airstrike in the southern suburbs of Beirut.

A cease-fire in Gaza, U.S. and Middle Eastern diplomats have said, could help persuade Iran and Hezbollah to rein in their promised strikes. Israel has vowed to respond powerfully to any attack on its territory, potentially dragging the region into an escalatory spiral.

As of Friday, Israeli intelligence had assessed that Iran and Hezbollah had lowered the level of alertness in their rocket and missile units, according to five Israeli officials. Israel now believes the Iranian-led response will take place at a later date, the officials said. Still, officials cautioned that their information and assessments were rapidly changing given the fluidity of events.

Over the past few days, international diplomats have shuttled across the region trying to head off a larger conflict. The United States has also sent additional combat aircraft, an aircraft carrier and a guided-missile submarine to the region, as it vows to defend Israel in the event of an attack.

On Friday, Israel Katz, the Israeli foreign minister, called on his country’s allies to threaten Iran more directly.

“The right way to deter Iran and prevent war is by announcing that if Iran attacks, they will stand with Israel not only in defense, but also in striking targets in Iran,” Mr. Katz said in a statement after he met with his British and French counterparts in Jerusalem.

A senior U.S. official said that it would be “ironic” if Iran launched an attack that would derail a deal to end the fighting and bring home the hostages. He said that when it came to support for a cease-fire deal, Iranian leaders had “an opportunity to put their money where their mouth is.”

Adding to the international pressure, the World Health Organization and UNICEF on Friday asked all parties to the war in Gaza to observe humanitarian pauses to allow more than 640,000 children in the territory to be vaccinated against polio. The request came as the first case of polio in the enclave in many years was confirmed by the Gazan Health Ministry.

The W.H.O. said the risk of the disease spreading was high because the war had prevented many children from receiving routine vaccinations.

Next week, Secretary of State Antony J. Blinken was expected to arrive in Israel for more diplomatic talks, including a meeting with Mr. Netanyahu, the Israeli prime minister’s office said in a statement.

Mr. Biden said in a statement on Friday that Mr. Blinken was traveling to the Middle East in part “to underscore that with the comprehensive cease-fire and hostage release deal now in sight, no one in the region should take actions to undermine this process.”

Reporting was contributed by Michael Levenson, Euan Ward, Ephrat Livni and Michael D. Shear.

The announcement that a new version of mpox had been discovered in Sweden this week was the first indication that the disease had slipped out of Africa, where it has caused an escalating crisis in the Democratic Republic of Congo.

The announcement on Thursday about the disease formerly known as monkeypox came just a day after the World Health Organization declared a global health emergency, and it confirmed fears that a further spread was inevitable.

The person with the disease in Sweden had traveled to an area affected by the disease.

The European Center for Disease Prevention and Control said it is “highly likely” that more imported cases would be confirmed, in large part because of frequent travel between Europe and Africa. The center advised member countries to increase preparedness and to issue travel advisories recommending that people traveling to affected areas see if they are eligible for vaccination.

Pamela Rendi-Wagner, the E.C.D.C. director, warned that as long as the outbreak in Africa was not under control, cases would continue to appear in Europe and North America too.

“We have to be concerned, even outside Africa, because with the increasing number and the fast spread, the likelihood of the introduction of cases in Europe and the U.S. will increase,” Dr. Rendi-Wagner said in an interview on Friday.

The E.C.D.C. on Friday raised the risk of people in the European Union contracting the new version from “very low” to “low,” but emphasized that people traveling to and from the affected areas in Africa need to take precautions and are at a high risk.

What do we know about the case in Sweden?

The new version of the disease that is dominant in Congo is known as Clade I. The older version, a form of which caused a global outbreak in 2022, is known as Clade II. (A clade is a genetically and clinically distinct group of viruses.)

The Swedish patient was the first Clade I case diagnosed outside of Africa.

The person was quickly diagnosed, treated and isolated in the Stockholm area, while health workers began contact tracing, according to Magnus Gisslen, a state epidemiologist with the Public Health Agency of Sweden. While Dr. Gisslen said no new cases have been identified, fears of a wider transmission remain.

“People are afraid. There are flashbacks to the Covid 19 pandemic,” Dr. Gisslen said, adding that his office had fielded concerned calls from people who had planned to travel to the affected region.

Sweden, Italy and Britain have all issued public health warnings and preparedness strategies.

Is this outbreak different from the one in 2022?

The short answer is: Yes.

Dr. Paul Hunter, an epidemiologist at Norwich University in England, notes that “we’ve got two epidemics going on.”

The 2022 outbreak was driven by a version called Clade IIb, which is predominantly spread through sexual contact. Men who had sex with men proved to be the most at-risk population, but behavioral changes and vaccinations curbed the spread. New infections are still occurring, and the W.H.O. reported 100 new cases in Europe in June and 175 in the Americas.

The deadlier Clade I version has caused 15,600 infections and 537 deaths in the Democratic Republic of Congo, according to African health authorities.

Clade I is further differentiated by how it is transmitted, and who is most vulnerable. Clade Ia is spread through household contact and exposure to affected animals, in addition to sexual contact. So far, it is young children who are most vulnerable to this subtype. It is unclear if children on other continents will be as susceptible because it’s not yet certain how the children in Africa are contracting the disease.

So far, Clade Ib appears to spread mainly through heterosexual sex. Swedish doctors confirmed that the patient in Stockholm has this subtype.

Mpox may resemble ordinary respiratory illnesses at first but later manifests as a raised rash in the mouth, hands, feet or genitals. The virus spreads mainly through close contact — directly with the skin or fluids of an infected person, or with contaminated bed linens and other items.

Two doses of the mpox vaccine Jynneos, made by the Danish drugmaker Bavarian Nordic and used against the 2022 version, should protect against all versions of the virus, experts said.

As with many other infections, most people with healthy immune systems are unlikely to become severely ill with mpox.

Has this new version of mpox spread elsewhere?

So far, Sweden is the only country outside of Africa that has identified a case of the new version.

Pakistan announced a new case of mpox Thursday, but health workers were still trying to figure out which form of mpox the patient has. A senior health official in Peshawar said the infected person was a 34-year-old who had recently traveled from a Gulf state and was the first case reported in the country since the beginning of the year.

For the moment, Dr. Giovanni Rezza, Italy’s former director general for prevention, and now a public health professor at San Raffaele University in Milan, considers the latest mpox outbreak a “regional emergency” in Africa, but that other places need to prepare now.

“It’s clear that Europe needs to keep its eyes open,” Dr. Rezza said.

What can Europe do to slow the spread of Mpox?

Besides trying to stop the spread in Europe by raising awareness among health professionals, by treating patients promptly and by testing close contacts, European countries can also try to help stem the disease in Africa.

The European Union said on Wednesday that it would donate more than 175,000 doses of the mpox vaccine to countries in Africa, Bavarian Nordic will donate 40,000 doses that will be distributed by the Africa Centers for Disease Control and Prevention and the United States is donating 50,000 doses. France also said it would donate vaccine doses to the affected countries in Africa.

Apoorva Mandavilli, Emma Bubola, Zia ur-Rehman Rachel Chaundler and Ségolène Le Stradic contributed reporting.

Iran is expected to delay planned reprisals against Israel for the assassination of a top Hamas leader in Tehran to allow mediators time to make a high-stakes push for a cease-fire to end the war in Gaza, U.S., Iranian and Israeli officials said on Friday.

Top American, Israeli, Egyptian, and Qatari officials met in Doha, the Qatari capital, for a second day of talks on Friday in an attempt to resolve remaining gaps between Israel and Hamas. As those talks concluded, a joint statement from the United States, Egypt and Qatar said a “bridging proposal” had been presented to both parties. Senior officials from those three governments are expected to reconvene in Cairo before the end of next week.

It was not immediately clear if this timeline would change Iran’s assessments.

For more than two weeks, the region has anxiously awaited Iranian-led retaliation for the assassination of Ismail Haniyeh, the leader of Hamas’s political branch, and Fuad Shukr, a top commander in Hezbollah, the Lebanese armed group backed by Iran. Iran and Hezbollah have both vowed revenge, raising fears of regional all-out war.

After the first day of talks ended on Thursday night, Mohammed bin Abdulrahman Al Thani, the Qatari prime minister, called the acting Iranian foreign minister, Ali Bagheri Kani. Mr. Al Thani encouraged Iran to refrain from any escalation given the cease-fire talks in Doha, according to two Iranian officials and three other officials familiar with the call, who spoke on condition of anonymity because they were not authorized to speak publicly.

By Friday, Israeli intelligence had assessed that Hezbollah and Iran had lowered the level of alertness in their rocket and missile units, according to five Israeli officials. Israel now believes the Iranian-led response — already apparently delayed several times — will take place at a later date, the officials said. The officials have cautioned that their assessments are rapidly changing given the fluidity of events. Intelligence has been sparse and changes frequently, and Iran and Hezbollah are known to be constantly assessing the situation.

Mr. Al Thani spoke with Mr. Bagheri Kani again on Friday after the talks in Doha concluded, the Qatari foreign ministry said in a statement. Both senior officials stressed the need for “calm and de-escalation in the region,” the ministry said.

Fears of a wider regional conflict threaten to compound the devastation caused by Israel’s offensive in Gaza, which has killed tens of thousands of Palestinians and destroyed large swaths of the enclave. Israel launched the war after Hamas carried out an expansive surprise attack on southern Israel that killed roughly 1,200 people and saw 250 others abducted to Gaza, according to the Israeli authorities.

Israel and Hamas have been negotiating on and off for months over a three-phase cease-fire deal which would see the gradual release of the remaining 115 living and dead hostages held in Gaza for Palestinian prisoners. Under the terms of the deal, Israel would withdraw forces from Gaza and both sides would ultimately reach a permanent truce.

Several key points of contention between Israel and Hamas remain unresolved despite repeated rounds of talks.

Hamas refused to participate in the latest round of deliberations, which it labeled a delaying tactic by Benjamin Netanyahu, the Israeli prime minister. But Hamas officials had voiced willingness to speak with mediators if significant progress was made in the summit, according to officials familiar with the matter.

Mr. Netanyahu has stiffened Israel’s terms for an agreement in recent weeks, including calling for Israeli troops to remain on the Gazan side of its border with Egypt to prevent Hamas from rearming itself.

Over the past few days, Western diplomats have repeatedly shuttled across the region in an attempt to head off the anticipated escalation between Israel and Iran.

On Friday, the British and French foreign ministers arrived in Israel to discuss the ongoing cease-fire talks, as well as attempts to avoid all-out war between Israel and Hezbollah. And Egypt’s foreign minister, Badr Abdelatty, who met with Lebanese officials in Beirut on Friday, said that a cease-fire in Gaza was “the basis for stopping the escalation” in the region, according to Lebanese state-run media.

And the U.S. secretary of state, Antony J. Blinken, announced that he would make his ninth visit to the region since the Gaza war began more than 10 months ago. The Israeli prime minister’s office said Mr. Netanyahu would meet with Mr. Blinken on Monday.

Aaron Boxerman contributed reporting from Jerusalem and Euan Ward from Beirut.

A day after the assassination of a senior commander of the Lebanese militant faction Hezbollah, the group vowed to retaliate against Israel. More than two weeks later, however, the response has not come as Hezbollah strikes a delicate balance between the vengeance it seeks and the risks of a backlash at home.

Lebanon is already deep in turmoil from a yearslong political and economic crisis, and its citizens are tired of strife. The country has careened from one crisis to the next since a 15-year civil war broke out in 1975. And if Hezbollah ends up in another punishing war with Israel now, the nation could well turn against it.

The Lebanese state is made up of a multitude of factions and sects and it has been controlled for years by an ineffectual caretaker government. Hezbollah, an Iran-backed Shiite Muslim group, is both part of that coalition government and considered the real power underpinning Lebanon.

As the dominant political and military force in the entire country, Hezbollah has everything to lose and knows it must tread carefully.

The group has cemented its position over the last three decades after outmaneuvering its domestic foes in a political system that divides power by sect. The group has amassed a large and potent arsenal and is more powerful than the national military. It controls or has oversight of the country’s most important infrastructure. And it has lifted up its constituents in the process, empowering, enriching and providing services to Shiites in Lebanon, a historically marginalized sect.

Many of Lebanon’s Shiites now benefit from a plethora of services run by Hezbollah, including quality health care, free education and even a boy scouts program. Meanwhile, a broken and broke Lebanese state struggles to provide even the most basic services, such as electricity, for all its citizens. And no other political party has the funds or organization to provide for their own sect as well as Hezbollah.

Hezbollah must balance its allegiances to Iran and the Palestinian cause with the tolerance, if not support, of the Lebanese people. If the group miscalculates in its retaliation, Israel has vowed a response that could devastate Lebanon again.

“Hezbollah is stuck,” said Alain Aoun, a Christian member of Lebanon’s parliament who is allied with Hezbollah. “They have to avenge the assassination of their commander, but the taste of 2006 is still in their mouths. And they know the Lebanese people cannot take it anymore.”

In 2006, Hezbollah and Israel fought a bloody, monthlong war that destroyed large swaths of southern Lebanon. Israel’s harsh response saw many Lebanese factions rally around Hezbollah. But the risk now is that many in the country may blame the militants for any further destruction rather than close ranks behind them.

Hezbollah has already been engaged in a low-level war with Israel for the last 10 months in support of Hamas, the armed Palestinian group that attacked on Israel on Oct. 7, setting off the war in Gaza. Hamas, like Hezbollah, is an Iranian ally.

Analysts say Israel and Hezbollah have carefully calibrated their attacks on each other so as not to provoke an all-out war. But there has been an ever-present danger that a single mistake or miscalculation could push one side or the other over the brink.

Those risks grew late last month when a rocket from Lebanon hit a soccer field in Majdal Shams, a Druse village in the Israeli-controlled Golan Heights, and killed 12 teenagers and children. Hezbollah denied that the rocket was its own, while U.S. and Israeli assessments concluded that it belonged to the group.

Israel retaliated in Beirut by assassinating the Hezbollah commander Fuad Shukr — a strike on the Lebanese capital seen as a potentially dangerous escalation.

That assassination came a day before a senior Hamas political leader, Ismail Haniyeh, was killed in Tehran, the Iranian capital. Iran and Hamas blamed Israel, which has not publicly taken responsibility for Mr. Haniyeh’s killing.

Western and Middle Eastern governments have been waiting anxiously to see how and when Hezbollah and Iran might retaliate while U.S. and Arab mediators redoubled efforts this week to reach an Israel-Hamas cease-fire in hopes that it would cool regional tensions.

The fear is that whatever comes next could snowball into a more intense, intractable and widespread regional war.

What matters most is not when Hezbollah will retaliate but how. Analysts say that the militants believe any attack on Israel needs to be strong enough to force Israel to rethink striking Beirut again, but not so spectacular that it provokes a devastating response against Lebanon.

“Hezbollah needs to respond in a big way to stretch Israel’s red lines but without crossing the threshold that will lead to an all-out war,” said Amal Saad, a lecturer at Cardiff University and leading Hezbollah scholar.

Any attack that kills Israeli civilians risks a potentially catastrophic counterattack on Lebanon.

Hezbollah hinted in June that it may have the intelligence and the military capabilities to penetrate deep inside Israel. It released drone footage of sensitive facilities, including an air base, in and around the city of Haifa.

Unlike Hamas in Gaza, Hezbollah has a much larger and more powerful arsenal at stake — tens of thousands of rockets and precision-guided missiles that can pummel towns and cities in Israel.

Hezbollah leader Hassan Nasrallah is well aware of the risks. Shortly after Mr. Shukr’s assassination, he addressed Israel and the world in careful language.

“I am not saying that the goal of this battle is to eliminate Israel,” Mr. Nasrallah said, softening his usual approach of calling for the annihilation of Israel, a long-term Hezbollah objective.

“The goal of this battle is to prevent Israel from winning” and from “eliminating the Palestinian resistance,” Mr. Nasrallah added, drawing a separation between the war in Gaza and Hezbollah’s support for Hamas, on the one hand, and the group’s larger, longer-running conflict with Israel.

Mr. Nasrallah said Hezbollah could retaliate separately from Iran, underscoring his group’s ability to act independently from its patron. He also said that forcing Israel to wait for a response was part of the group’s psychological warfare.

The attack that killed Mr. Shukr last month was in Dahiyeh, a Shiite neighborhood in Beirut’s southern suburbs that was flattened during the 2006 war, the last high-intensity conflict between Israel and Hezbollah. Israel also struck important national infrastructure.

Mr. Nasrallah said in 2006 that he would not have ordered the capture of two Israeli soldiers — the incident that sparked the conflict — if he had known it would lead to such a war.

In subsequent years, oil-rich Gulf nations led by Saudi Arabia spent billions of dollars to rebuild Lebanon. But if all-out war breaks out between Israel and Hezbollah now, the Gulf is unlikely to help reconstruct Lebanon on the scale it did then.

Saudi Arabia and Iran had engaged in a decades-long war of influence across the Middle East, and Lebanon was often ground zero. Iran-backed Hezbollah eventually won out against the Saudis’ Lebanese allies about a decade ago. For those reasons, robust Gulf support is unlikely this time around, even if tensions between Saudi Arabia and Iran have eased lately.

By the time the latest warfare erupted around the region, Lebanon was already severely weakened from years of political paralysis and economic decline.

Its economy collapsed in 2019, with the currency losing more than 95 percent of its value, wiping out the savings of many. That crisis precipitated a political collapse, and the caretaker government put in place at the start of 2020 was too broke to provide the most basic services to the country.

For all those reasons and more, most Lebanese do not have appetite for another big war with neighboring Israel.

In Dahiyeh last week, the usually packed Beirut suburb was eerily quiet. Normally bustling shops and streets were empty as many appeared to have fled the area, worried about a new conflict.

Sabah Suleiman was working as a seamstress next to the building Israel struck when it killed Mr. Shukr. She said she was trapped in her workshop when the strike destroyed much of the block.

Ms. Suleiman urged Hezbollah to retaliate but, at the same time, said she had deep concerns.

“I worry about my family,” she said, adding that she did not know where they would seek refuge if the conflict intensified.

Fatima, 50, lives near the Lebanese-Israeli border and said her house had been badly damaged by Israeli shelling in the past months. She recently fled for Beirut, but said she does not feel safe anywhere, fearing what a Hezbollah retaliation may bring in terms of an Israeli response.

“We are terrified,” said Fatima, who asked to be identified by her first name only so she could speak freely about Hezbollah. “Lebanon is weak economically and if we open another war, how are we going to face it? We have no water and no electricity,” she added.

“I have lost count of the retaliations. We are heartbroken. But this war is bigger than us.”

This could have been a new era for Thai democracy.

The public resoundingly ended a near-decade of military rule last year, handing an electoral mandate to a progressive party and a forceful prime minister candidate who represented none of the old power makers.

Just 15 months later, things are entirely different, and the voters had nothing to do with it. The winning party has been banned, and its candidate barred from holding office. The consensus choice who emerged then to form a government as prime minister was abruptly ousted by a top court this week.

On Friday morning, Parliament dealt the next card up, choosing Paetongtarn Shinawatra — the 37-year-old heir to a powerful and polarizing Thai political dynasty — to be the country’s new prime minister.

For many Thais, the decisions made in the past week were the latest evidence that the country is controlled by a military and royalist establishment that is bent on denying the people’s will, using the courts and the army’s presence to winnow the field.

The sudden rise of Ms. Paetongtarn has seemingly settled a period of political limbo, at least for a while. But it has added to the frustration of voters and political activists who had worked within the democratic system.

“I don’t understand what kind of games they are playing,” said Nawaphon Thoopkaew, 23, a student at Kasetsart University. “And for what?”

The selection of Ms. Paetongtarn was a result of a two-day backroom negotiation that began hours after the former prime minister, Srettha Thavisin, was ousted by the Constitutional Court on an ethics violation charge. She received 319 votes in the House of Representatives, surpassing the 247 she needed. There were no other candidates.

“I hope I can do my best to make this country go forward,” a visibly nervous Ms. Paetongtarn told reporters, adding, “my hands are shaking.”

Ms. Paetongtarn’s acceptance of the nomination surprised some observers. People close to her had previously said she was reluctant to jump into the fray. A former deputy chief executive of a family-run hotel management company, Ms. Paetongtarn’s résumé is thin for someone seeking national leadership, having played only advisory roles rather than directly governing.

But she is the daughter of Thaksin Shinawatra, the tycoon who once led the country as prime minister. After he was ousted by a military coup in 2006, his supporters battled anti-Thaksin forces in violent street protests that carried on for years. Even through the roughly 17 years he was in self-imposed exile, his political parties and his chosen candidates continued to win elections.

Ms. Paetongtarn was one of those chosen candidates in the election last year, an early front-runner for Pheu Thai. Her youth presented a possible appeal for a generation of voters that has gravitated toward the mostly young opposition.

On Thursday evening, when her nomination to become prime minister was put forward, Ms. Paetongtarn told reporters that she is close to her father, who always gives her advice.

If her main asset is that she is a Shinawatra, it is also one of her biggest troubles. Thailand’s politics are perilous, and few understand that as intimately as her family.

Her aunt, Yingluck, Thailand’s first female prime minister, was ousted in a 2014 coup and had to flee the country. Her uncle, Somchai Wongsawat, was also removed as prime minister when the Constitutional Court ordered the dissolution of his People Power Party in 2008.

Ms. Paetongtarn’s ascension means that Mr. Thaksin is again at the forefront of Thai politics, a prospect unthinkable until a few years ago. His return was in part set in motion by his rivals, beginning with last year’s victory by the Move Forward Party.

The election results stunned an establishment that saw that party, which had championed changes to a law that makes criticism of the monarchy a crime, as a dire threat. Blocking its rise required teaming up with Mr. Thaksin, whose Pheu Thai Party was the second-biggest in the winning coalition.

Pheu Thai ultimately defected and joined the conservatives. After Mr. Thaksin made a surprise return to Thailand, it was soon clear what the quid pro quo was. Although given an eight-year sentence for corruption and abuse of power, he never had to serve a day in jail.

But Mr. Thaksin has seemingly fallen out with the establishment again. In June, he was indicted on accusations of insulting the monarchy. At the same time, the case against Prime Minister Srettha, his protégé, began moving forward, ending with his ouster by the Constitutional Court on Wednesday.

Now it is Ms. Paetongtarn’s turn in the spotlight, and she will be closely scrutinized by Mr. Thaksin’s rivals and by the establishment.

For the 72 million Thais stuck in an exhausting cycle of elections, party dissolutions, protests and coups, there is a dreary sense of déjà vu.

The political upheaval has taken a toll on Thailand’s once-surging economy, now among the region’s weakest. Many of the country’s young professionals are determined to leave Thailand, in part because of the politics.

“It tells you that the Thai people’s vote doesn’t really matter, because in the span of one week, the court disenfranchised more than 14 million voters and unseated a democratically elected prime minister,” said Napon Jatusripitak, a visiting fellow with the Thailand Studies Program at Singapore’s ISEAS-Yusof Ishak Institute.

“To me, this amounts to a judicial coup that not only nullified the election results, but also establishes a very dangerous legal precedent that allows judicial institutions to intervene and check the power of future democratically elected governments for many years to come.”

But others say there is still room for optimism. One striking feature of Thailand is that despite all the repression at the top, voter and civic engagement remains high. It is home to a vibrant opposition and civil society organizations unafraid to speak up.

“The one thing that, for better or worse, is really enshrined in this system, is the idea of having elections, regardless of how seriously those elections are taken,” said Michael J. Montesano, associate senior fellow of the Thailand Studies Program at the ISEAS-Yusof Ishak Institute.

The public has not come out in the streets to protest the latest machinations, a difference from previous instances when democracy was interfered with. The Move Forward Party, which won the most votes in last year’s election and then was banned, has constantly reminded people to make their voices known at the ballot box.

The party has a successor already vowing to keep up the fight: the People’s Party. Their supporters believe that a repeated election victory for the party in three years’ time could make it harder for the establishment to repudiate the results.

Within hours of its launch last Friday, it exceeded its fund-raising target, three weeks ahead of schedule.

Kasit Piromya, a former foreign minister, points out that most of the generals and the heads of Thailand’s political parties are in their 70s, while the People’s Party is made up of people in their 30s and 40s, with new ideas and a firm ideology.

“This is the last hurrah of the establishment to retain power,” he said.

Muktita Suhartono contributed reporting.

Thailand’s Parliament chose Paetongtarn Shinawatra, 37, to become the country’s prime minister on Friday, elevating a candidate with no governing experience to the leadership of a nation in profound political turmoil.

Here is what to know:

Heir to a Powerful Political Dynasty

Ms. Paetongtarn, also known by her nickname, Ung Ing, is the third and youngest child of the tycoon Thaksin Shinawatra, 75, who was prime minister from 2001 to 2006. The political parties he founded, including the Pheu Thai party his daughter now represents, consistently won elections. He was removed in a coup but has wielded influence even while living in exile to escape corruption charges.

Ms. Paetongtarn’s uncle, Somchai Wongsawat, was also removed as prime minister in 2008, when the Constitutional Court ordered the dissolution of his party.

Her aunt, Yingluck Shinawatra, 57, is a former prime minister who has faced the same fate. A younger sister of Mr. Thaksin, she became prime minister in 2011 and was removed in a coup in 2014 and fled the country in 2017 to avoid criminal negligence charges.

Background and Education

As a child, Ms. Paetongtarn shadowed her father while he campaigned and played golf. She graduated from Chulalongkorn University, one of Thailand’s top schools, with a degree in political science. She studied international hotel management at the University of Surrey in England.

She was 20 when she witnessed the Thai army’s coup against her father. She helped lead a family-run hotel management company. And then she was drafted into politics last year, joining the populist Pheu Thai party and becoming a front-running candidate for prime minister. The campaign fell during the last trimester of her pregnancy with her second child.

“My passion is hotel,” she said in an interview in March 2022. “But after having a child, my thinking changed,” she added. “I want to make the country livable for my children.”

Her Leap to Center Stage

Ms. Paetongtarn’s rise has kindled a nostalgia for the legacy of her family among its supporters. Among critics, it has also fueled condemnation of its past scandals and questions about her credentials besides her family name.

“I have a solid team, a team that once was a government, once served the people, once pushed policies successfully,” she said in an interview in March 2023. “That made me dare to say that I am ready.”

Despite her influential family ties, many, including party insiders, considered her unready to lead the nation because of her lack of political experience. Pheu Thai ultimately chose Srettha Thavisin as its candidate. But it later named Ms. Paetongtarn as its party leader.

Her Rise to Prime Minister

Pita Limjaroenrat, a politician of the Move Forward Party, won the most votes in the election with a pro-reform agenda that, among other issues, called for changes to a law that made it a crime to criticize the Thai monarchy. But the military-appointed Senate rejected the results, voting not to let him become prime minister. The Constitutional Court also banned his party.

Mr. Srettha became prime minister in 2023. But less than a year later, on Wednesday, the Constitutional Court ousted him, finding that he had violated ethics standards. Pheu Thai on Thursday chose Ms. Paetongtarn as its candidate to be Mr. Srettha’s successor, and she accepted the nomination.

Ms. Paetongtarn faces a floundering economy, and as she takes office, she is seen as likely to continue some of Mr. Srettha’s economic stances, including advocating for lower interest rates and less autonomy for the central bank.

And hanging over her is the possibility of pressure from the military and its royalist allies. Many accuse them of repeatedly undermining the democratic process, and they have seemingly turned against their recent and uneasy understanding with her father.

Muktita Suhartono contributed reporting.