A general in charge of the Russian military’s nuclear and chemical weapons protection forces was killed by a bomb on a Moscow street on Tuesday, in one of the most brazen assassinations since Russia’s full-scale invasion of Ukraine nearly three years ago.

The general, Igor Kirillov, 54, died along with an aide after an explosive device planted in a scooter was detonated on Tuesday morning near the entryway to a residential building, Russia’s Investigative Committee, a law enforcement agency, said in a statement.

An official with Ukraine’s security service, known as the S.B.U., said that Ukraine was responsible for the killing. The official, who spoke on the condition of anonymity to discuss a sensitive intelligence operation, confirmed the details of the assassination given by Russia.

The S.B.U. considered General Kirillov a legitimate target, the official said.

A day before the general’s killing, Ukraine had accused him of criminal activity, saying he was responsible for the “massive use of banned chemical weapons” in Ukraine. The security service said that Russian troops had dropped ammunition with toxic compounds onto Ukrainian positions in efforts to force Ukrainian soldiers out of their trenches.

According to the Russian military, the division that General Kirillov oversaw carries out specialized tasks like protecting Russian troops when chemical and nuclear weapons are used, as well as offensive operations like attacks with incendiary weapons.

General Kirillov was the head of Russia’s radioactive, chemical and biological defense forces. He helped develop a thermobaric rocket launcher, the TOS-2, according to a biography published by RIA Novosti. The Russian military frequently reports its use in Ukraine.

His apparent assassination represents the highest-profile such death of a Russian military official far from the battlefield since the start of the invasion of Ukraine in 2022. While other Russian generals have died in occupied Ukraine or near the front line, he is the highest-ranking military official to have been killed inside Russia.

General Kirillov, who once headed a Russian military academy, was also prominent in Russia’s propaganda campaign against Ukraine and the West, frequently addressing the news media and appearing on television with unfounded claims. In 2023, for instance, he said that the United States was planning to use drones “designed to spread infected mosquitoes.”

General Kirillov also claimed that Russian forces had uncovered a Ukrainian chemical weapons production laboratory near Avdiivka, a Ukrainian city that Moscow’s troops captured in February. Part of the buildup to the war was an effort by Russia to portray Ukraine, without evidence, as a hub for producing weapons of mass destruction at the behest of the West. Ukraine vigorously denied the claim.

The explosion that killed General Kirillov occurred about 6:12 a.m. and was so powerful that it damaged windows as far up as the third floor and shattered them in a building across the street, the RIA Novosti state news agency reported.

Another state news agency, Tass, said investigators had found a hidden camera used to monitor General Kirillov in a car-sharing vehicle nearby.

In a video that the S.B.U. official shared with The New York Times and other news outlets, recorded from the interior of a car, two people can be seen leaving a building just moments before a blast. The New York Times verified that the video was recorded from a vehicle used for short-term rentals and it matched the details in the footage with the location and time when General Kirillov was killed.

In the clip, a scooter stands next to the building’s door, where the explosion appeared to have taken place, matching a description given by Russian investigators about where the explosive was planted.

The bomb had the force of more than two pounds of TNT, Tass said, citing investigators.

There was no comment from the Kremlin in the hours after the killing on Tuesday, though Russian state television carried it as a top story in daytime news broadcasts, calling it a “tragedy.”

At Russia’s lower house of Parliament, the body’s chairman, Vyacheslav Volodin, held a moment of silence for the general and described him as “not only a military leader, but first and foremost a scientist.”

A senior American official said on Tuesday that the United States was not informed about the planned assassination. The official said it could be counterproductive because it might trigger a severe reaction from Russia’s president, Vladimir V. Putin. U.S. officials have generally disapproved of sabotage and targeted killings inside Russia for that reason.

Other American officials cautioned that General Kirillov was not a key commander and did not play an important role in the war. One official predicted Russia would seek to retaliate by taking out a similarly positioned Ukrainian military officer, but the officials are skeptical that the assassination will lead to any significant escalation on the battlefield.

The S.B.U. is Ukraine’s main domestic security agency, with responsibilities that include counterintelligence and tackling organized crime and terrorism. During the war, its duties have extended to conducting sabotage operations and killings inside Russia, in a campaign targeting prominent pro-Kremlin figures and military officials.

Unable to halt a grinding Russian advance on the battlefield, Ukraine has increasingly carried out deadly covert actions. Just last month, the S.B.U. took credit for a car bombing that killed a senior commander of the Russian Black Sea Fleet in Russian-occupied Crimea. The same agency carried out attacks on the bridge connecting Crimea to Russia in 2022, disrupting flows of military supplies.

U.S. officials believe Ukraine’s security services were behind the 2022 killing of Daria Dugina, the daughter of a prominent Russian nationalist. And the S.B.U. claimed responsibility for the assassination last month of Valery Trankovsky, a senior Russian naval officer, who Ukraine said had ordered missile strikes at civilian targets. Both were killed in car bombings.

Ukraine uses these kind of covert operations to help compensate for its disadvantages against its larger, better equipped adversary, analysts say.

John Foreman, a former British defense attaché in Moscow and Kyiv, said the assassination had two main goals: retaliating for the use of chemical weapons on the Ukrainian battlefield and sending “a clear message to all those politicians and military officers responsible for planning, directing and supporting Russia’s illegal war in Ukraine” that they too are at risk.

But for all the concern the killing may raise in the Russian Army, it is unlikely to change the situation on the battlefield, Mr. Foreman added. The Kremlin remains determined to fully occupy the four Ukrainian regions it has declared its own and “is not backing down,” he said.

The S.B.U. said that Russian forces, on General Kirillov’s orders, had used chemical weapons on the battlefield more than 4,800 times since the war began. Russia denied the accusations during a July meeting of the Organization for the Prohibition of Chemical Weapons.

Ukraine has said the chemical weapons used by Russia often include combat grenades equipped with the irritant chemical agents CS and CN. Those tear gases, most commonly used by riot police officers to control crowds, are banned in warfare under the Chemical Weapons Convention, an arms control treaty ratified by more than 150 countries, including Russia.

The Conflict Intelligence Team, a Russian open-source research group operating from exile, has said that Russian forces have used tear gas on the battlefield in violation of international conventions. The group has said that photo and video evidence has suggested that Russian troops used grenades with tear gas against Ukrainian soldiers.

The U.S. State Department said this spring that Russia had used chloropicrin, a choking agent widely used in World War I, as well as tear gas on the battlefield. Britain imposed sanctions on General Kirillov this fall for his responsibility in deploying chemical weapons in Ukraine.

The Organization for the Prohibition of Chemical Weapons in May called the situation in Ukraine “volatile and extremely concerning regarding the possible re-emergence of use of toxic chemicals as weapons.” But it said that accusations of chemical weapons use in the war were “insufficiently substantiated.”

Maria Varenikova contributed reporting from Kyiv, Alina Lobzina from London, Aric Toler from Kansas City, Helene Cooper and Julian Barnes from Washington and Nataliya Vasilyeva from Istanbul.

On the second floor of the Shababeek cafe, overlooking the clock tower square in the city of Idlib, the side reserved for men was empty except for two young men nursing cups of Turkish coffee. The family side, where women are allowed, was nearly full.

There was no music — just the hiss of an espresso machine and the clinking of cups — and unlike cafes elsewhere in Syria, the air was clear of hookah smoke. That is because of an agreement the owner had to sign with Hayat Tahrir al-Sham, the Islamist group that has ruled for years in much of Idlib Province, in northwestern Syria, and which now controls most of the country with other rebel factions.

“Hookahs and music were banned from the beginning,” said Yahia Naeme, the owner of the cafe, who said the ban had lost him business because many people used to come to his cafe specifically to smoke hookahs. “If we can’t offer it, they’ll get bored and go elsewhere,” he said.

Other cafes in Idlib have skirted the law by offering hookahs in speakeasy-type environments behind closed doors. But Mr. Naeme did not want to risk running afoul of the area’s rulers.

The bans on hookahs and music at cafes were part of a few religious laws initially imposed on Idlib by Hayat Tahrir al-Sham when it took power there in 2017, which also included attempts to impose a stricter dress code for women and a ban on the sale and purchase of alcohol.

The group has ruled Idlib with an authoritarian hand, imprisoning and torturing some critics, according to residents and human rights groups. But even those who chafe under its rule say that Hayat Tahrir al-Sham has been pragmatic and shown flexibility.

The group has brought order to a devastated region, and reversed some laws after a backlash from residents. Early on, for instance, a morality police patrolled streets and government buildings, but that practice was later ended.

It also did not adopt the brutal methods of extremist groups like the Islamic State, which sometimes punished people with public executions, instead imposing mainly fines for people breaking laws.

The group has also been desperate to shed its image as a group once affiliated with Al Qaeda. Despite that and attempts to gain international legitimacy, the group is still designated as a terrorist organization by the United States and the United Nations.

In Idlib, Hayat Tahrir al-Sham has sought to win over hearts and minds and prove its governing credentials by undertaking public works. It has paved roads, provided regular running water and electricity and repaired war damage — things that are lacking in the rest of Syria.

Traffic police officers direct busy intersections and roundabouts while street cleaners keep the roads clean. Homes, apartments and even the tents of people displaced by war have been numbered in a project to assign addresses to millions of residents.

Next to the stenciled-on address numbers hang bright green electricity meters — with the power coming from Turkey. That starkly contrasts with areas of Syria that were until recently under the control of the Assad government, where residents mostly rely on generators for power.

After consolidating control over Idlib Province by attacking other rebel groups, Hayat Tahrir al-Sham brought order to a chaotic region. It has also enjoyed a reputation for avoiding corruption, a relief for many in a country where the government ran on bribes and connections.

For now, there is excitement — and a bit of apprehension — about what comes next. Even some of the group’s critics are waiting to see how it evolves and grows to manage a whole country, one that is more diverse and less conservative than Idlib.

In a display case at the Shababeek cafe is a new offering: caramel layer cake with icing in the colors of the changed Syrian flag.

That flag now decorates much of the city, along with reminders to the population about who has provided their public services up to now.

On Friday, after weekly prayers, couples, families and young men in camouflage — a few carrying Kalashnikovs — descended on a central roundabout to celebrate the ouster of the Assad regime.

In a small park in the center was a plaque installed by the Hayat Tahrir al-Sham government: “Renovation of the Seven Seas Roundabout and the area around it — 2021.”

The roundabout was also the scene months earlier of demonstrations against the group’s administration by hundreds of residents, one of many protests that took place across Idlib Province.

They were protesting the imprisonment and torture of critics and the imposition of taxes that have been a heavy burden for many residents, according to Syrians for Truth and Justice, a human rights advocacy group.

Muhammad Ali Basha, a 30-year-old rebel fighter and resident of Binnish, a town in Idlib Province, said he had participated in some of the protests.

“Security-wise, we saw that their behavior was starting to resemble the behavior of the Assad regime,” he said in his house, adding that Hayat Tahrir al-Sham and its security arm would raid homes without notice.

On a dresser next to him were three guns — two AK-47s and a handgun — a Syrian flag and a slew of gold decorative butterflies, positioned like a shrine.

In some cases, Hayat Tahrir al-Sham responded to the protests with force, according to Syrians for Truth and Justice.

The rebel group has denied taking harsh action against residents of Idlib during the protests.

“When people say there was a violent response, no there was not,” Ahmed al-Shara, the group’s leader, formerly known by his nom de guerre, Abu Mohammad al-Jolani, said in an interview with The New York Times. “There was a response to some people who were destroying people’s properties.”

He conceded that some of the calls of the protesters were valid, in that certain laws were putting undue economic pressure on residents. “We remedied these and appeased a large part of the population,” he said.

Custom taxes, which were imposed on people coming from other parts of Syria, were done away with, residents said.

Residents and human rights groups also say that repression against critics has relented in recent months following the protests.

The experiences of Muna Armanazi, the 63-year-old principal of a private school in the city of Idlib, underline the mixed feelings many residents have about the rebel group.

On a residential street on Saturday, Ms. Armanazi was overseeing workers repairing and rebuilding walls and classrooms damaged in one of the last airstrikes carried out by the Syrian regime before its ouster. The strikes also killed two people, she said.

In the days after the strike, Ms. Armanazi went to the city’s public works ministry to ask for help rebuilding the damage to her school. She was told to bring the receipts for the damage and that the government would help cover it, she said.

“The institutions are working well,” she said, even if she was sometimes frustrated with how slowly things happened. “Their social services are good.”

“But,” she added, “in the beginning, when they first came, there was chaos.”

She cited the hard-line religious stance initially taken and later dropped by the group, including trying to force women to wear face coverings.

Ms. Armanazi, as an observant Muslim, wears a white hijab, a head scarf that leaves her face uncovered, and an ankle-length black robe outdoors. But her clothing was not conservative enough for members of the group, she said.

Once, as she was walking down the street, she passed a Hayat Tahrir al-Sham fighter. He chided her for how she was dressed — “Fear God, sister,” she said he told her.

“I said, ‘You fear God and lower your gaze and keep walking,’” she recalled saying defiantly back to him. But he did not respond further.

Before they were disbanded a few years ago, the morality police would not only harass women but also men with tattoos, said Salwa Jabaan, 51, a journalist with various local media, including the Aleppo Today TV channel.

“They were interfering in every part of our lives,” said Ms. Jabaan, who also took part in some of the protests against the rebel administration.

There had been some efforts in the past to revive the morality police, she said. But those efforts were abandoned after opposition from women and as the group began to evolve. Now she sees an even more drastic evolution in the group and in Mr. al-Shara, its leader, as they seek greater international legitimacy.

“Things have changed a lot over the past few years,” Ms. Jabaan said.

Muhammad Haj Kadour contributed reporting.

The authorities in the French archipelago of Mayotte introduced a curfew on Tuesday as they rushed to get food and water into the territory in the aftermath of a tropical cyclone that killed at least 22 people and flattened entire neighborhoods.

Hundreds or even thousands are feared dead as a result of Tropical Cyclone Chido, which barreled into Mayotte, a series of islands off the eastern coast of Africa, over the weekend. French officials have said it could take days to know the true death toll, because roughly a third of the territory’s 320,000 residents are undocumented immigrants, and many live in shanty towns.

The cyclone also slammed into Mozambique with heavy rains and strong winds, killing at least 34 people and completely or partly destroying over 35,000 houses, according to the United Nations Office for the Coordination of Humanitarian Affairs. Aid agencies fear that number also may increase as the scale of the disaster becomes clearer.

Officials who toured Mayotte said the devastation had spared no corner of the tiny archipelago, France’s poorest territory. Videos released by France’s interior ministry showed emergency workers sawing through fallen trees to disentangle them from power lines and clear roads. About 70 percent of the road network has been cleared of debris from the storm, the ministry said on Tuesday.

Communication in the territory is still hampered by downed networks. The International Federation of Red Cross and Red Crescent Societies said on Tuesday that it had lost contact with over 200 volunteers in Mayotte.

The curfew will be enforced from 10 p.m. to 4 a.m., France’s interior ministry said, although it said that unrest and looting had been minimal. President Emmanuel Macron of France is expected to visit in the coming days.

Ambdilwahedou Soumaila, the mayor of Mamoudzou, the capital, told RFI radio on Tuesday that more than 1,400 people had been injured in the storm. About 8,000 people have taken shelter in schools, the authorities said.

The territory is often sheltered from the brunt of storms by neighboring Madagascar, he noted — but this time, the cyclone passed above the tip of Madagascar and hit Mayotte with full force.

“This natural phenomenon didn’t give our territory a chance,” Mr. Soumaila said.

He said that rescue workers had not yet reached many of the hillside shanty towns around Mamoudzou, where the storm uprooted trees and left piles of twisted, corrugated metal.

“Some areas are completely devastated,” he said. “The priority today is food and water.”

Réunion, a French island about 900 miles southeast of Mayotte, has become a staging area for rescue efforts and aid equipment, including thousands of tarps. France’s interior ministry said on Monday evening that it expected half of Mayotte’s drinkable water supplies to be restored within the next 48 hours, and 95 percent within the week. The authorities also said that the territory’s single hospital would be bolstered by a field hospital in the coming days.

But the local authorities worry about the spread of disease if aid does not reach residents and if rescue workers cannot pull dead bodies out of the wreckage quickly enough.

“We could be facing a health crisis very soon,” Ben Issa Ousseni, the president of Mayotte’s local council, told local television.

As the rain has dissipated, aid agencies worry that stagnant water could lead to the spread of diseases like cholera and malaria. Mozambique had just recently overcome the worst cholera outbreak in 25 years.

In recent years, Mayotte has experienced high levels of illegal immigration from nearby Comoros. Bruno Retailleau, France’s departing interior minister, said on Monday that some undocumented residents had not gone to officially designated shelters in time. That has raised questions about whether fears of arrest or deportation hampered the territory’s preparedness efforts.

In Mozambique, the coastal province of Cabo Delgado was worst affected, with 28 people killed by the storm and at least 300 injured.

The region is already struggling to house thousands of people displaced by a yearslong insurgency waged by a group backed by the Islamic State. The fighting has already displaced more than half a million people in the region of Northern Mozambique, leaving more people vulnerable to extreme weather and natural disasters.

Lynsey Chutel and Nazaneen Ghaffar

The Pentagon has seen “indications” that the North Korean forces who have been sent to Russia to help the Kremlin in its war against Ukraine have suffered their first casualties, according to a U.S. official.

Air Force Maj. Gen. Pat Ryder, the Pentagon spokesman, told reporters on Monday that the North Koreans had entered combat last week in the Russian region of Kursk.

Russia has been trying to recapture territory in the region after Ukraine seized parts of it in a surprise cross-border offensive launched in August.

“We do assess that North Korean soldiers have engaged in combat in Kursk,” General Ryder said. He added: “We do have indications that they have suffered casualties, both killed and wounded.”

General Ryder gave the assessment a day after Ukraine’s military intelligence agency said that at least 30 North Korean soldiers had been killed or injured along the front line in Kursk over the weekend, in the Russian villages of Plekhovo, Vorozhba and Martynovka. The claims could not be independently verified.

The move this fall to deploy thousands of North Korean forces in Russia’s war against Ukraine rattled Kyiv’s allies and set the stage for a larger conflict between Moscow and the West.

Ukrainian officials said initially that they were frustrated by what they described as a muted response from allies after they learned of the deployment of North Korean forces to Russia.

But last month, President Biden directly responded, granting Ukraine permission to use American long-range missiles against certain military targets across the border because Russia had brought North Korean troops into the war, U.S. officials said at the time.

In June, President Vladimir V. Putin of Russia and Kim Jong-un, North Korea’s leader, revived a mutual defense pledge, deepening ties that stretch beyond the Cold War.

Ukraine and South Korea first warned about the movement of North Korean troops to Russia in mid-October. In early November, General Ryder said that at least 10,000 North Korean troops had traveled thousands of miles from eastern Russia to the Kursk region, which borders Ukraine.

The Pentagon said the Kremlin had amassed a combined force of 50,000 Russian and North Korean troops to push out Ukrainian forces from Russia.

There have been daily rumors about the North Koreans — about what they are eating, where they are and how they are communicating with Russians.

The remarks on Monday, however, represented the first official confirmation by the Pentagon that the North Koreans are engaged in combat in Kursk. So far, the deployment of the North Koreans has been limited to Russian territory.

Oleksiy Melnyk, a military analyst and former Ukrainian commander, said the number of troops was relatively small, but it could have huge implications if Russia gives North Korea any advanced technology for its help.

The move also was designed to provoke the West, he said. “It’s just testing the ground,” said Mr. Melnyk, now a senior official at the Razumkov Center, a nonprofit institute in Kyiv. “What will the Western reaction be?”

President Volodymyr Zelensky of Ukraine said on Saturday that Russia had begun to use a significant number of North Korean soldiers in assaults in Kursk. He also said that Ukraine had information “suggesting their use could extend to other parts of the front line.”

Yurii Shyvala contributed reporting.

The leader of the rebel coalition that took power in Syria this month said that all armed opposition groups in the country would be dissolved, Syrian state media reported on Tuesday, as the new government worked to build a functioning state.

Ahmed al-Shara, the head of the coalition, said that the rebel fighters would be brought under the authority of the defense ministry. It was not clear how or when this would be achieved, or whether the competing armed factions would agree.

But Mr. al-Shara said, “Everyone will be subject to the law,” according to Syria’s state news agency, SANA.

His comments came more than a week after the fall of Bashar al-Assad’s regime, as the new authorities in Damascus sought to project stability after 13 years of civil war, while aiming to shore up international recognition through a series of meetings with diplomats from Europe, the United Nations and the Middle East.

As regional powers continued to jockey for control and influence in Syria, Prime Minister Benjamin Netanyahu of Israel made a trip on Tuesday to territory in southwestern Syria that his country’s military seized after rebels toppled the Assad regime. Israeli forces have pushed beyond Israeli-controlled areas in the Golan Heights and a buffer zone along the border for the first time in decades, capturing an area that includes the summit of Mount Hermon.

Mr. Netanyahu said Israeli forces would remain on the mountain “until another arrangement is found that guarantees Israel’s security.”

He was accompanied by Israel’s defense minister, Israel Katz, and other officials. A statement issued later by Mr. Katz’s spokesman, Adir Dahan, said they had visited “outposts on the peak of Mount Hermon,” about six miles from the border of the Golan Heights.

The statement offered an expanded rationale for an ongoing Israeli presence there, saying that holding the mountain summit would enable the military to better observe Hezbollah militants in the Bekaa Valley of neighboring Lebanon. The Israeli military must complete the construction of fortifications and arrangements for soldiers “to fully prepare for the possibility of an extended presence at the site,” Mr. Katz said in the statement.

Syria’s new leadership is likely to view the Israeli move into Syrian territory and the officials’ unannounced trip as provocative. The visit and the military maneuvers showcase some of the challenges facing the former rebels now holding Damascus, the Syrian capital, as they struggle to consolidate territorial control in the face of outside interests.

In an interview with The New York Times and other news outlets on Monday, Mr. al-Shara criticized the Israeli military’s advance into and beyond the buffer zone, and said Syria would continue to abide by the 1974 agreement that followed the end of the 1973 war. He called on the international community to make sure that Israel followed it, too.

Domestically, Mr. al-Shara’s attempts to consolidate power are accelerating with the announcement that rebel groups would be disbanded. The United States, other countries and the United Nations still consider the rebel group led by Mr. al-Shara, Hayat Tahrir al-Sham, to be a terrorist organization. That label severely limits the aid that countries and organizations can provide to the new government. Mr. al-Shara has called on nations to remove the designation.

Secretary of State Antony J. Blinken said over the weekend that the United States had been in direct contact with the rebels and that the United States was prepared to help them “succeed.”

While pushing to maintain law and order, Mr. al-Shara also appears to be trying to get public institutions back up and running, and to restore vital infrastructure in the country. “Syria is tired of wars, and we want to build a state and institutions away from conflicts,” he said in the interview on Monday.

Those state-building efforts are beginning to take shape.

Preparations are underway to reopen Syria’s two main airports, in Damascus and Aleppo, and Syria’s state news agency has been broadcasting administrative bulletins about central bank exchange rates and recruitment calls for the police, once a feared tentacle of the Assad regime’s security apparatus.

The new Interior Ministry announced that applicants could enroll in police academies in Damascus and other major cities, and directed them to a registration link to begin the process.

SANA, once an arm of the Assad government, has been posting daily updates in an apparent attempt to allay concerns over potential instability. On Monday, the state-run news agency posted pictures of clean floors and welcome signs at the Aleppo airport, a sharp contrast with the images of armed fighters roaming the terminal just days earlier, after they captured it in a lightning-fast advance across the country.

The news agency also reported a meeting between top British diplomats and Mr. al-Shara, who urged Britain to lift sanctions imposed on Syria under the Assad regime and to restore relations between the two countries.

More widely across Europe, Ursula von der Leyen, president of the European Commission, said on Tuesday that the European Union would have to continue its engagement with Hayat Tahrir al-Sham and other factions in Syria to help the country rebuild.

“We would need to start a discussion on sanctions reliefs,” she said, speaking alongside President Recep Tayyip Erdogan of Turkey in Ankara. “But this can only happen if real progress on a peaceful transition is seen on the ground.”

Ms. von der Leyen also said that Europe was committed to supporting Syria’s reconstruction and that the first delivery of supplies donated from Europe would arrive in the coming days. The European Commission said last week that it would give more than 100 tons of food, medicine and health supplies to Syria.

Mr. Katz, Israel’s defense minister, seemed to strike a much more pessimistic tone on Tuesday about the new Syrian government, referring in his statement to “rebels in Damascus who claim to portray a moderate facade but are among some of the most extreme branches of Islamists.”

In addition to taking territory in the Golan Heights and southwestern Syria, Israel has conducted waves of airstrikes over the past week aimed at destroying Syrian military assets, including tanks, weapons production facilities and air-defense systems. Israel said it aimed to keep those assets out of the hands of “extremists.”

The Israeli government also approved a plan this week to expand settlements in the part of the Golan Heights that it controls, a move that could double the area’s population. Israel seized the Golan Heights during the Arab-Israeli War of 1967, and the area is considered illegally occupied under international law.

Johnatan Reiss contributed reporting from Tel Aviv.

Kim Jong-un, the leader of North Korea, has taken his boldest diplomatic gamble by supplying an estimated 11,000 troops and stockpiles of weapons to Russia to support its war against Ukraine.

The deployment provides timely foreign aid for Russia’s war efforts, with North Korean troops fighting alongside Russian forces in the Kursk region to help them retake territories lost to Ukraine. On Monday, Maj. Gen. Pat Ryder, the Pentagon spokesman, said the Pentagon had seen “indications” that an unspecified number of North Korean soldiers had been killed and wounded there.

Sending the troops brings a range of benefits for North Korea, including much-needed cash and diplomatic leverage. Mr. Kim is receiving billions of dollars’ worth of food, oil, cash and advanced weapons systems from Russia that will help his regime endure international sanctions and upgrade its conventional armed forces, analysts say.

Mr. Kim had been in desperate need of such a breakthrough.

A triple whammy of incidents has rocked his dynastic regime over the past decade. First, American-led U.N. sanctions devastated North Korea’s economy by banning all its major exports, including coal, seafood, textiles and workers, as well as sharply curtailing its oil imports. Mr. Kim sought to lift the sanctions through direct diplomacy with former President Donald J. Trump. But the negotiations collapsed without an agreement in 2019,​ tarnishing Mr. Kim’s domestic image as an infallible leader. Then, the pandemic further crippled the North’s economy.

Pyongyang provides troops, missiles and howitzers.

North Korea looked more isolated than ever when it saw opportunities opening up as President Vladimir V. Putin’s invasion of Ukraine dragged on. Russia was using up troops and ammunition, and North Korea had plenty of both to offer. Its military is one of the world’s largest conventional armed forces, with 1.3 million members. And it kept huge stockpiles of artillery shells, rockets and other conventional weapons — many of them outdated — as well as new ballistic missiles it developed under Mr. Kim’s ambitious arms-buildup program.

The courtship started when North Korea invited Russia’s then-defense minister, Sergei Shoigu, to a massive weapons parade in Pyongyang in July last year. North Korean weapons began flowing into Russia soon afterward. When Mr. Putin invited Mr. Kim to a summit meeting in the Russian Far East in September last year, Russia showed off what it could offer North Korea in return, taking Mr. Kim on tours of a space launch facility, an aircraft factory and a naval ​port.

In June, Mr. Kim and Mr. Putin signed a treaty of mutual defense and cooperation in Pyongyang. North Korea began sending troops to Russia afterward.

North Korea has also provided Russia with 20,000 shipping containers’ worth of weapons, including millions of artillery shells, newly developed ballistic missiles, multiple-launch rocket systems and long-range howitzers, South Korean officials have said.

Mr. Kim met with Russia’s new defense minister, Andrei R. Belousov, in Pyongyang on Nov. 29, vowing to continue support for Russia and “vigorously expand” ties.

That meeting heralded more troops and weapons supplies from North Korea, said Yang Moo-jin, president of the University of North Korean Studies in Seoul.

Brisk weapons exports to Russia are bringing life to North Korea’s munitions industry. Mr. Kim has called for increased production when he visited weapons factories in recent months and for mass manufacturing of attack drones. North Korea is also expanding a missile-manufacturing factory in an apparent effort to produce more KN-23 missiles, which it has supplied to Russia to use against Ukraine, according to researchers at a U.S.-based think tank.

Russia pays with oil, food and weapon upgrades.

The North has earned up to $5.5 billion through arms deals with Russia,​ according to Olena Guseinova, a researcher at the Hankuk University of Foreign Studies in Seoul​. In a report published in October​, she also estimated that North Korea could ​bring in up to $572 million annually through deploying troops — a huge sum by the ​North’s standards​. The country’s official exports amounted to $330 million only last year.

Neither Russia nor North Korea has revealed how Moscow was paying North Korea.

But North Korean oil tankers have been bringing in far more oil from Russia than is allowed under U.N. sanctions, according to an analysis of satellite imagery published last month by the UK-based Open Source Center and the BBC.

On the ground, North Korea’s military is also gaining valuable battlefield insights for the first time in decades, including innovations in drone use that are changing modern warfare. The war against Ukraine is providing North Korea with its first opportunity to test its newer KN-23 and KN-24 ballistic missiles against Western air defense systems in live combat. Its technicians traveled with the missiles to identify the deficiencies​ and collect data to take home, according to officials in South Korea.

One fear in Seoul is that in the future Mr. Kim may be able to bargain for Russian help to master technologies needed for nuclear missiles that could hit targets across the Pacific.

“I don’t think they have yet reached the stage where Russia would provide sensitive nuclear and missile technologies and components,” said Jang Seho, an analyst at the Seoul-based Institute for National Security Strategy.

The new stream of revenues and weapons technologies from Russia will cushion North Korea from U.N. sanctions and embolden Mr. Kim​’s postures toward Washington and its allies. It remains to be seen if President-elect Trump seeks to resume his personal diplomacy with Mr. Kim.

What are the risks for Mr. Kim?

But the deployment also carries several risks for Mr. Kim.

The North Korean special forces have been fighting alongside Russian paratroopers and marines to help Russia retake territories lost to Ukraine in its Kursk region, South Korean intelligence officials said. They were trained to infiltrate by sea and river and across Korea’s hilly terrain. It was unclear how well they were prepared for a war of attrition fought in trenches and on flatlands with artillery and drones, military experts said.

South Korean officials are closely monitoring how the North’s weapons and troops fare in the war — with the potential for battlefield desertions — to glean insights into ​its military’s preparedness. Many of the North Korean artillery rounds were decades old and have proven to be duds.

The drain on its supplies may weaken North Korea at home.

​North Korea has already sent so many conventional weapons and ammunition to Russia “it cannot fight a war ​in Korea right now even if it wanted to,” said Doo Jin-ho, a senior analyst at the Korea Institute for Defense Analyses in Seoul.​ “That may be Kim Jong-un’s biggest vulnerability now.”

​Some South Korean analysts doubt that collaboration between Pyongyang and Moscow will endure.​ The two economies have so little to offer each other that Russia would account for less than 2 percent of North Korea’s international trade other than arms deals, while China accounts for more than 90 percent, according to a report by researchers at the Korea Institute for International Economic Policy.

But even bilateral trade between North Korea and China slowed to $1.5 billion in the first nine months of the year, down from $1.6 billion during the same period a year ago.

That may reflect another gamble by Mr. Kim. North Korea has long sought to play Beijing against Moscow, but some analysts say that North Korea’s deepening military ties with Russia could damage its relations with China.

Hamas said on Tuesday that “serious and positive talks” were taking place to reach a deal with Israel to finally end the war in Gaza and free the remaining hostages held there.

Officials from countries involved in the talks say both sides might be nearing a truce in the war that began with Hamas’s attacks on Oct. 7 last year. It would be the first pause in the fighting since November 2023 when Israel and Hamas agreed to a weeklong cease-fire that gave Gazans a brief reprieve and freed 105 hostages.

But months of negotiations have seen hopes rise repeatedly, only to be dashed days later by a fresh impasse.

Here’s what we know so far.

What’s on the table?

In a change from previous negotiations, both sides have generally refrained from leaking the details of the talks to the media. Some analysts said they believed the blackout indicated that Israel and Hamas were more serious about an accord this time around.

According to officials familiar with the talks, mediators have floated a cease-fire beginning with a 60-day truce. During this phase, Hamas would release some of the 100 or so hostages still held in Gaza — some of them dead — in exchange for Palestinians jailed in Israel.

Qatari and Egyptian mediators, who have brokered the talks alongside the United States, hope the initial truce will continue into a permanent cease-fire.

Israel has demanded that its forces largely remain in two segments of Gaza: one, known as the Netzarim corridor, through central Gaza, splitting the northern and southern parts of the enclave; and the other, called the Philadelphi corridor, along the territory’s border with Egypt.

Hamas has previously demanded a swift and complete Israeli exit from the enclave. But the group is now willing to tolerate an extended Israeli presence in parts of those two corridors as long as Israel eventually withdraws, according to a person familiar with Hamas’s thinking.

Why has the war gone on so long?

For months, Israel and Hamas were deadlocked.

Israeli leaders, including Prime Minister Benjamin Netanyahu, vowed to eradicate Hamas in Gaza after the Oct. 7 attacks killed about 1,200 people in Israel, the deadliest day in the country’s history.

Hamas said it would not release any more hostages unless Israel agreed to end the war, completely withdraw its forces and release scores of Palestinians in Israeli jails.

Qatar and Egypt, as well as the Biden administration, pitched both sides on a three-phase agreement, hoping to build momentum. Those efforts repeatedly broke down.

Israeli critics accuse Mr. Netanyahu of putting his own political fortunes and the desires of his political allies above the fate of the hostages. His governing coalition relies on far-right parties that have opposed ending the war, hoping to control Gaza and build Jewish settlements there; they could topple the government if they reject a cease-fire the prime minister approves.

Mr. Netanyahu says he is doing everything he can to free the hostages, although he has said that he will not compromise on eliminating Hamas.

Hamas has also kept fighting despite the enormously heavy price for Gaza’s civilians: about 45,000 people killed and many more wounded, Gaza health authorities say, and about two million forced from their homes amid widespread destruction. Some Palestinians say Hamas is now battling to salvage its own postwar rule in Gaza, rather than for any larger cause.

What might have changed?

Over the past few months, the momentum in the Middle East has radically shifted, creating what some officials and diplomats are calling favorable conditions for a deal.

In early December, President-elect Donald J. Trump vowed on social media that there would be “ALL HELL TO PAY” unless the hostages were released by his inauguration on Jan. 20. “Those responsible will be hit harder than anybody has been hit,” he wrote.

Many in Israel saw that message as aimed at Mr. Netanyahu as well as Hamas. Mr. Trump has called on Israel to “finish up” the war, although his vision for a postwar settlement in Gaza remains unclear. The pace of talks accelerated after Steven Witkoff, whom the president-elect has named his Middle East envoy, met with Mr. Netanyahu and the Qatari prime minister in November.

U.S. officials have suggested that Israel has accomplished nearly everything possible through military might in Gaza. Many Israelis are also deeply worried about the fate of the remaining hostages, whose families fear they might not survive another winter in captivity.

At the same time, many of Hamas’s leaders and fighters have been killed, and the group is more isolated than ever. Israeli officials say they hope that could push the group toward a compromise.

Hamas’s ally Hezbollah had insisted that it would keep firing rockets and drones at Israel until it ended the war in Gaza. But after Israel killed many of Hezbollah’s leaders and operatives, the Lebanese militant group buckled and consented to a separate peace last month.

Soon afterward, rebel forces swept into the Syrian capital of Damascus, toppling the decades-long rule of Bashar al-Assad. Mr. al-Assad was a key ally of Iran, which also backs Hamas and Hezbollah. Both groups now see their patron in retreat across the region.

Hamas’s leaders once dreamed of a regional war against Israel alongside other Iran-backed militias. But they now realize that the “cavalry is not coming to the rescue,” Secretary of State Antony J. Blinken said in early December.