Just hours after President Bashar al-Assad boarded a plane for Russia on Sunday, thousands of Syrians who had fled to escape his rule and the civil war to unseat him celebrated in the streets across Germany.

The political reaction in Berlin came nearly as quickly. By Monday, far-right and even some mainstream politicians were calling for the return of some of the nearly one million Syrians who have made Germany home.

“Many refugees who have found protection in Germany are now finally hopeful of being able to return to their Syrian homeland and rebuild their country,” said Nancy Faeser, the German interior minister, who is responsible for refugees.

Several European countries, including Britain, Germany, Greece, Italy and Sweden, swiftly announced that they would temporarily suspend legal proceedings considering asylum status for Syrians. Austria went a step further and announced that it would also prepare to deport Syrians whose claims for asylum fail.

The primary reason cited by the various authorities was that the Assad regime from which the asylum seekers had fled no longer exists. For now, they added, it was unclear whether Syria would remain as oppressive and as unsafe as before.

But there was also little disguising the enthusiasm in parts of Europe that Mr. al-Assad’s ouster might help ease Europe’s migration problem by allowing Syrians to return home or by turning new applicants away.

Jens Spahn, a German health minister under former Chancellor Angela Merkel, alluded to that possibility in a TV interview on Monday. “What if the German government said: ‘We will charter planes for anyone who wants to go back to Syria, and we will give them 1,000 euros to get them started’?” he said, referring to a sum worth about $1,000.

To the many Syrians who have successfully and painstakingly integrated in European society, such comments were troubling.

“It was shocking that on the same day that the Assad regime fell, we immediately heard politicians from Germany and all over Europe, talk about when and how the Syrians should go back,” said Anas Aboura, 38, a curator and artistic director in Hamburg who arrived from Syria in 2015 and was granted asylum.

“No, I’m sorry,” he added, “We are an established community, and we are established here as individuals, and it is up to us to decide when and how to go and help rebuild Syria.”

No other European nation has welcomed as many Syrian refugees as Germany. As chancellor, Ms. Merkel refused to close the borders in 2015 when nearly a million fled to her country.

While more than 100,000 are now German citizens, the influx is blamed for helping to fuel the rise of the xenophobic far-right Alternative for Germany party, which routinely denigrates single young men from Syria and Afghanistan.

Since a deadly knife attack during a street fair in Solingen in August by a Syrian asylum seeker, even mainstream politicians have called for tighter restrictions on migration. As Germany prepares for elections early next year, nearly all parties, including the left-leaning Greens, are in favor of curbs.

Gerald Knaus, a migration expert who has advised the German government, said that any discussions about sending Syrians established in Europe back home was largely political posturing. In reality, courts would most likely prevent such deportations because many European countries prohibit sending asylum seekers back to dangerous situations.

“Nobody falls for the idea that you could get someone to move back to Syria just for €1,000,” he said.

Susan Fratzke, a Germany-based senior policy analyst at the Migration Policy Institute, a think tank, said it was unsurprising that countries would pause decisions on asylum claims given that the situation had changed substantially. Still, given the uncertainty in Syria, any decision to reject providing a form of protection would be premature, she noted.

Yet in much of Europe, countries have adopted or are considering harsher policies than before, and the decisions to suspend Syrian asylum applications are taking place in the context of heated debates over irregular immigration.

Yvette Cooper, home secretary for the center-left Labour government in Britain, said in a statement posted on social media on Monday that her country would join others in suspending decisions on asylum applications from Syrians.

“We have seen some people returning to Syria,” Ms. Cooper said. “We also have a very fast-moving situation that we need to closely monitor.”

“That is why,” she added, “like Germany, like France and like other countries, we have paused asylum decisions on cases from Syria while the Home Office reviews and monitors the current situation.”

The French national asylum agency said on Monday that it was “closely following” the situation in Syria but stopped short of a blanket suspension of all applications from Syrians. The agency said that requests would be examined on a case-by-case basis.

“As is always the case when the situation in an asylum seeker’s country of origin changes, this may lead to a temporary suspension of decisions on certain asylum applications from Syrian nationals,” the agency said in a statement.

On Wednesday, Greece, too, announced that it would be halting asylum claims for Syrians. “We’ve announced a freezing of the whole process,” the country’s migration minister, Nikos Panagiotopoulos, told Greek radio. “Until we see, weigh the facts and see how things develop on the ground.”

He added: “At the moment, one thing is certain: Asylum can no longer be given to a Syrian citizen when they cite persecution by the Assad regime from the moment that the Assad regime no longer exists.”

The decisions to suspend asylum applications for Syrians will leave thousands in a legal limbo. At the moment, for example, 9,500 await decisions in Greece, 7,300 in Austria, 6,500 in Britain, and 700 in France.

But in Germany alone, 47,270 people are on the list.

Tareq Alaows, 35, fled to Germany in 2015 and now works for Pro Asyl, a nongovernmental organization helping refugees. “I sense great fear and instability in the community because Germany could think of nothing better than to start a debate about a return less than 24 hours after the fall of the regime,” he said.

Since arriving, Mr. Alaows has learned to speak near-perfect German. He even ran for Parliament in 2021 as a Green Party candidate though later dropped out. He watched the Assad ouster unfold from Berlin, devouring social media and sharing the news with friends and family.

He said that the most poignant moment was when he saw video of Syrians tearing down a statue of Mr. al-Assad’s father, Hafez al-Assad: He knew it well because it stood just several hundred yards from the house where he grew up in Damascus.

“When I was born, that statue was there, and I’ve been wanting to remove it my entire life,” he said. “I wished I could have been there with my people for that moment.”

Germany has its own experience with repressive regimes, he noted, and would do better helping Syrians with the fallout than talking about repatriation.

“We need support because peace in Syria will only be possible when there is justice,” he said.

Reporting was contributed by Aurelien Breeden from Paris, Emma Bubola from Rome, Stephen Castle from London, Jenny Gross from Brussels and Niki Kitsantonis from Athens.

President Emmanuel Macron on Friday tapped François Bayrou, a veteran centrist politician and one of his top allies, as the new prime minister, a move that few expect would stabilize France’s roiling politics.

Mr. Bayrou becomes the country’s fourth prime minister this year — an ominous record. The task ahead is immense: He must now form a cabinet capable of shepherding bills through a fractured, cantankerous lower house of Parliament that ousted his predecessor last week.

Most urgently, he will have to finalize an emergency budget to avoid a shutdown of essential state services before the new year as France wrestles with ballooning debt and a large budget deficit.

Mr. Macron has said he wants a broad cross-section of parties, excluding extremes on the right and left, to work together in the country’s interest. But his pick suggested a reluctance to stray too far from his agenda — despite his party’s defeat in snap elections this summer — and will do little to quell fury from his opponents.

“I am fully aware of the Himalaya of difficulties that lie before us,” Mr. Bayrou said in a speech before taking office. But he said he would strive to achieve a “necessary reconciliation” of France’s divided society.

Mr. Bayrou, 73, is a fixture of French politics — a former lawmaker and three-time presidential candidate who was first elected to local office four decades ago. He is the longtime mayor of Pau, in southwestern France, and he was education minister in the 1990s.

He is the founder and leader of the Mouvement Démocrate, or MoDem, a centrist party that is part of a coalition alongside Mr. Macron’s Renaissance party.

As a politician who battled to create an independent middle party, Mr. Bayrou helped pave the way for Mr. Macron’s first-term victory in 2017, bowing out of the race and endorsing Mr. Macron instead. Since then, Mr. Bayrou has played the role of mentor — an ally, but not an indebted one.

“He won’t be a servant of Macron,” said Vincent Martigny, a political science professor at the University of Nice, Côte d’Azur, adding that at a time of great uncertainty, Mr. Bayrou could seem “a reassuring choice for many people.”

“He knows the right and the left, he’s talked to both sides forever,” Mr. Martigny added, comparing Mr. Bayrou to President Biden. “People will pick up the phone for him.”

His weakness, however, is that “he will be held responsible for everything that Macron has done till now,” Mr. Martigny said.

Mr. Macron did not need parliamentary approval to appoint Mr. Bayrou. But to survive, the new prime minister must avoid a no-confidence motion in the lower house, which could be supported by the left and the far right. That unusual pairing brought down the previous prime minister, Michel Barnier, last week.

France’s nationalist, anti-immigrant far-right National Rally party, which had accused Mr. Barnier’s budget of hurting the purchasing power of French people, said on Friday that it was waiting to see how Mr. Bayrou would proceed.

“I’m not brandishing the threat of a no-confidence vote morning, noon and evening,” Ms. Le Pen, who heads National Rally lawmakers in the lower house, told reporters. But, she warned, “I am not renouncing that tool.”

There were varied reactions from the New Popular Front, an alliance of left-wing parties that came ahead in the snap election and is still furious Mr. Macron has not asked them to govern.

Representatives of France Unbowed, a leftist party that is one of the alliance’s main drivers, immediately rejected Mr. Bayrou as an extension of Mr. Macron and his pro-business agenda.

“The country has two clear choices: continuing ill-fated policies with François Bayrou, or making a clean break,” Mathilde Panot, a top France Unbowed lawmaker, wrote on X as she called for a no-confidence vote against him.

Other members of the left-wing alliance were more measured. Socialist and Communist leaders criticized the appointment of a major Macron ally but said they were waiting to see whether Mr. Bayrou would compromise with other parties.

In particular, they will insist that he refrain from pushing bills through without a final vote, as Mr. Barnier did this month over the budget, setting in motion the no-confidence vote that made him the shortest-tenured prime minister in modern French history

Some of Mr. Macron’s opponents have called for his resignation, placing the blame for the political deadlock on his decision to call the snap elections in the summer.

Mr. Macron has rebuffed those calls. But the repeated delays in appointing Mr. Bayrou reflected the complicated political equation he faces. No party or bloc has a majority in the lower house, and few are inclined to work together.

On Thursday, Mr. Macron even cut short a visit to Poland to appoint the new prime minister, only to postpone a decision yet again, fueling hours of feverish speculation on news channels.

Mr. Macron’s choice, in the end, is a familiar one — both for voters and for himself.

“The more the president loses ground, the more he clings to those closest to him,” Marine Tondelier, the head of France’s Green party, told BFMTV.

Rémi Lefebvre, a political science professor at the University of Lille, said Mr. Bayrou could claim strong support from only about 160 centrist lawmakers, just a little more than a quarter in the 577-seat lower house.

Most of the left sees him as too right wing, and some on the right see him as too moderate — or even as a traitor to a longtime partnership between conservative and centrist parties, especially after he voted for a Socialist candidate in 2012.

“This government is even more fragile than the preceding one,” Mr. Lefebvre said, adding that Mr. Macron’s pick showed he was adrift.

“He doesn’t accept that he lost power, but at the same time, he has lost,” he said. “So we are all stuck in this contradiction.”

Mr. Bayrou’s predecessor was unable to pass a budget — the left and far right had railed against proposals to save $60 billion through a mix of budget cuts and tax increases — and his government’s first order of business will be to pass the emergency finance bill.

That bill is designed to avoid a state shutdown on Jan. 1, allowing the government to collect taxes at their current level and to borrow money on financial markets.

Civil servants would be paid and state institutions would continue to function, but no investments could be made and little would be done to address the country’s troubled finances.

Parties across the spectrum have suggested that they would support the emergency bill to prevent a calamitous budget crunch.

Still, Mr. Bayrou will face strong political headwinds next year when he tries to push through an actual budget and other bills.

“I think he has a chance of not being censured for six months,” Mr. Martigny, the analyst, said. “But I’d be surprised if his government lasts more than a year.”

Ségolène Le Stradic contributed reporting.

Everything happened so fast. On their first in-person date, they went to see a play, and she whispered in his ear, “I think I’ve fallen in love with you.” Soon after, they were married. And shortly after that, he was sent back to the front.

When Damina Serbyn and Roman Myronenko met at a theater in Kyiv, the Ukrainian capital, last year after a short online courtship, they dreamed of spending their lives together in domestic bliss. But with Mr. Myronenko fighting Russian forces on the front line, that has yet to happen. Ms. Serbyn lives alone, and has to travel for hours every two weeks to see her husband, a deputy commander of a drone battalion based near the northeastern city of Kharkiv.

On a recent cold winter evening, she was on a train rolling into Kharkiv that was carrying other women coming to see their loved ones at the front — a dangerous journey to a city that has come under constant attack by missiles and drones. When the door opened, Ms. Serbyn jumped off the train and into her husband’s arms, kissing him.

When she is away, he does not feel like he is truly living, said Mr. Myronenko, 38. Ms. Serbyn, also 38, is a clerk with the government gas company. “Without her, nothing makes sense,” he said.

As the war drags on, and as Russian forces make steady advances into Ukraine, soldiers are fighting with little hope of being demobilized any time soon and returning home to their loved ones. Many women, determined to maintain their relationships and keep their families strong, make risky trips to areas near the front, often taking children along.

Some travel to places like Kharkiv, which are usually more dangerous than the cities and towns where they live. Others travel to frontline bases, where they are often in even more peril.

“I was scared,” said Kateryna Kapustina, 32, a journalist, who brought Yaroslav, her 9-year-old son, to spend their vacation in a frontline village where her husband, Ihor Kapustin, 34, is based. In civilian life, Mr. Kapustin was a mechanic; in the war, he often has to tow broken vehicles from perilous positions facing Russian forces, she said.

“My son and Ihor are all I have,” Ms. Kapustina said. Before she began making regular trips to the front, she said, “I felt like we were getting too used to living without one another.”

Yulia Hrabovska, 35, a voice actress from Kyiv, was four months pregnant when her husband, Volodymyr Hrabovsky, went to war. When she visits him near the front line, they usually stay indoors and try to have a homey life — lying in bed or watching a movie together. Sometimes she cooks his favorite banana pancakes. “We try to imagine that for these two days, there is no war,” she said.

They became friends when she was his teacher at a drama school, but never thought of starting a romantic relationship until Russia’s full-scale invasion of Ukraine in February 2022.

Along with other friends, the two sheltered in the first days of the invasion at her parents’ home.

In mid-March, when Russian tanks were roaring past on the highway next to her village, Semenivka, in the Poltava region of eastern Ukraine, she took his hand. “I thought to myself, please God, let us all survive. If we will all survive, I will kiss him.”

Mr. Hrabovsky was thinking of kissing her, too, while holding her hand in her parents’ garden and listening to the Russian tanks.

They did survive and kiss, and have been dating ever since.

Ms. Hrabovska said the news that her husband was going to deploy to the front came just after she got pregnant.

“Those were very difficult days,” she said. “It was scary to imagine the baby growing up without a father.” But then she said realized that other women were going through the same thing. “Other girls manage it somehow, so I will, too. There are a lot of us.”

Kharkiv, close to the battle lines and full of soldiers, has become a hot spot for frontline dates. The train station has two flower shops whose main clients are soldiers.

Not far from the flower shop is a hairdressing salon. Karina Semenova, 42, said that nearly all of her clients were soldiers, and that “they all miss love and care.” (She found a romantic partner from the front line, a soldier, when he came in to get a haircut.)

Some women come bearing food for their husbands and their comrades.

Before traveling recently to see her husband, a soldier based outside the contested town of Vovchansk, northeast of the city of Kharkiv, Yevheniya Dukhopelnykova, 47, spent an entire day cooking.

She made at least six different dishes for her trip, including mushroom pâté, baked pork, baked duck and a hot chile sauce that her husband’s entire unit now loves, she said. She also prepares dried meat and bakes croissants.

The next day, she made the eight-hour journey by car from the central Ukrainian village of Pavlysh to see her husband, Mykhailo Chernyk, 44, a junior sergeant. When she arrived, it was already dusk. Her husband walked toward her along the village street, where military vehicles are visible outside houses where soldiers are quartered.

She stopped the car and ran out to kiss and hug him. “I need him to keep me warm,” she said. They brought the food inside the house where he lives with other soldiers, and he opened the bag with croissants and took a bite of one, smiling.

Hanna Zaporozhchenko, 40, made the trip to the front to bring her husband, Sgt. Stanislav Zaporozhchenko, a surprise present for his 38th birthday. He ran to meet her train with a bouquet.

The family has two children, 11 and 5. They miss their father, but she said she would not risk taking them along.

Of their dates, she said, “He has a totally different life now, but when we speak, often he starts falling asleep, as he says he starts feeling relaxed.”

She feels like she must now give her exhausted husband support. “I came because I love him,” she said. “I am his wife and his mental health support.”

Women also say they are willing to make the risky journeys since they know they may never see their husbands again if they do not.

Alina Otzemko, a clinical psychologist, said she visited her husband, Vasyl Otzemko, nine times in a year and a half. She always took her son along.

In June, Mr. Otzemko was killed in action. But because of their trips, the couple’s 4-year-old son at least remembers his father, she said.

“Now I understand that I did everything right,” she said. “It’s good that I didn’t listen to anyone who tried to talk me out of it. It was the only way to keep my son’s memory about his daddy,” she said.

Before her husband was killed, Ms. Otzemko published a book for children and their parents to help explain “why daddy is not at home.”

She has now written a new one that she said helped her come to grips with her loss: “Why Daddy Died.”

Olha Konovalova contributed reporting from Kyiv, Ukraine.

Her brother was pulled from his car at a military checkpoint nearly a decade ago, her brother-in-law dragged from his house by the police. Two of her cousins were arrested near the airport in the Syrian capital, Damascus. She said she never had heard from any of them again.

So after the fall of President Bashar al-Assad on Sunday, Ghusun Juma, 35, began a quest for answers that led her to an underground prison in one of Syria’s most notorious detention centers, a drab collection of buildings in southeastern Damascus.

“I am looking to see if there is anything that belonged to my brother, his ID card, or something with his name on it,” she said, guiding herself through a dark, dank cell block with a cellphone flashlight. “I have been looking since the first day, but I haven’t found anything anywhere.”

Mr. al-Assad’s ouster, and his troops’ abandonment of their bases as rebels stormed through Damascus, has exposed the black boxes of one of the Arab world’s most repressive regimes. While some Syrians have wandered through his luxurious palace, many more have combed through the vast network of detention centers whose repression helped keep him in power.

An untold number of Syrians disappeared into the maw of that security apparatus over the decades. As the rebels broke into prisons and freed prisoners over the last few weeks, many Syrians hoped that their missing relatives would soon return home.

In Damascus, families have set out to look for their loved ones. All week, they have been driving around the city, asking at hospitals and clawing their way through dirty cells in now empty detention centers, hoping to find some trace of their relatives, alive or dead.

One of those notorious facilities — a security complex known as Branch 235, or Palestine Branch — was run by military intelligence in southeastern Damascus. The complex sits behind forbidding concrete blast walls on a main boulevard and contains nearly a dozen buildings, including offices and barracks for soldiers and officers, many of them just a few floors up from the prison.

In 2012, Human Rights Watch said inmates there were regularly beaten, electrocuted and hung upside down. Three years later, the group found that conditions inside were so bad that prisoners often died from gastrointestinal infections, skin diseases, torture and starvation.

Now, the complex stands empty. Guarded by rebels, its buildings have been ransacked by looters or charred black and gray from fires.

During a visit this week, reporters from The New York Times found entire rooms packed with munitions — hand grenades, bullets, explosives and tear gas canisters — indicating a heavily armed force.

In the basement below a soldiers’ barracks were a dozen underground cells that were barely long enough for a tall man to lay down. They had low, concrete ceilings and no light source other than small holes in the heavy metal doors.

Graffiti on the wall of one cell included a bouquet of flowers and a pack of Hamra cigarettes, a Syrian brand. Drawings in another cell included large female eyes and a heart with an arrow piercing it.

The main prison, however, was on the two underground floors of an unimposing seven-story building nearby.

There, large cells once held many dozens of prisoners who shared a pit toilet with no door and most likely slept close together on the floor. Cockroaches ran across the walls, and the smell of sweaty bodies still hung in the air.

Other cells were smaller, likely for isolation. In a separate wing, women’s clothing was strewed across the floor next to tiny plastic sandals, indicating mothers jailed with their children.

“I was here, in this room!” screamed a veiled woman in a long black dress who was peering into a cell by the light of her cellphone flashlight. “This is where they put me for four and a half months.”

She said she had been locked in the small, windowless room in 2020 with dozens of other women. She did not say what she had been accused of.

“We slept on top of each other,” she said. “They did not feed us, they beat us.”

She confirmed that children had been present, with mothers from Lebanon, Iraq and Chechnya whom the government had accused of terrorism.

Although Mr. al-Assad had fled Syria and his military and security forces had melted away as the rebels advanced on Damascus, she was still scared, and she gave only her first name, Hanaa.

“They will come back and kill us,” she said.

Many of the facility’s offices still contained voluminous paperwork, including investigation reports, case files, personnel lists and prisoner registries. Scattered in the mess left by looters who came after the guards fled and before the rebels took control were dozens of Syrian and Iraqi passports, ID cards and photos, probably of former inmates.

Rights groups hope that such paperwork will be preserved, potentially to serve as evidence in war crimes trials or to help families determine what became of their missing loved ones.

In an interview, Stephan Sakalian, head of the International Committee of the Red Cross in Syria, said that since the start of the Syrian conflict in 2011, the committee had received more than 30,000 tracing requests from families looking for relatives.

Those included people arrested by the government and by armed groups as well as those who had disappeared at sea while trying to migrate to Europe, he said. Most of them had not been found.

Documents from prisons, hospitals and other institutions captured by rebels could provide critical clues to the fate of many of the missing, he said. But only if they are preserved.

“So far, no one has taken charge of the custody of these important documents,” Mr. Sakalian said. “Every single document could be the key to helping a family find someone who’s missing.”

In the prison’s lowest level, Mohammed Kanaz, 62, wept as he walked from cell to cell, looking for any trace of his son, Mohammed, who he said had been arrested at age 18 in 2012.

“I raised him and loved him and he shined in my eyes,” he said. “What did he do?”

Mr. Kanaz’s brother, too, had been arrested, at a military checkpoint in 2014, and the family was informed two years later that he had died in this prison.

“He died of a heart attack,” he said sarcastically, assuming the real cause of death had been mistreatment. “All the Syrian people died of heart attacks.”

But Mr. Kanaz had never received any information about his son.

In a large storeroom where prisoners had surrendered their belongings, he found a large registry with inmates’ names and their dates of admission.

“If he is dead, may God have mercy,” he said, flipping frantically through its pages to look for his son’s name. “If he is alive, where is he?”

Russia launched a missile attack on Ukraine’s energy infrastructure early Friday, in an assault that President Volodymyr Zelensky described as “one of the largest strikes” on his country’s power facilities.

The attack consisted of 93 missiles and 200 drones, Mr. Zelensky said on social media, “including at least one North Korean missile.”

Ukraine’s energy minister, Herman Halushchenko, said on Facebook, “Once again, the energy sector across Ukraine is under massive attack.”

Of the 81 missiles that Ukraine managed to shoot down, 11 were intercepted by F16 fighter jets provided by allies, Mr. Zelensky said. He once again urged Ukraine’s partners to respond, saying, “The world can stop this madness.”

The International Atomic Energy Agency had made a renewed call on Thursday for Russia to stop targeting Ukraine’s energy infrastructure: The agency’s board of governors signed a resolution addressing the threats that the attacks pose to nuclear safety.

“The international community must increase pressure on Russia for its deliberate attempts to create a radiation disaster on the continent,” the resolution said.

The agency said after Friday’s attack that five of Ukraine’s nine operating nuclear reactors had to reduce their power output because of Russia’s “renewed attacks on energy infrastructure.”

The first reports of damage after the assault came from western Ukraine. The Lviv and Ternopil regions reported power outages, and Svitlana Onyshchuk, the head of the Ivano-Frankivsk military administration, said on social media that her region had experienced “the most massive attack since the start of the full-scale war.”

Russia launches exploding drones at Ukraine nightly. The larger waves, which combine various types of missiles along with the drones, have come every few weeks and are typically aimed at electrical infrastructure such as power plants, in a long-running campaign to black out the country.

Military analysts had speculated this week that President Vladimir V. Putin of Russia could try to escalate these attacks as a show of force after the fall of President Bashar al-Assad of Syria, Russia’s ally.

Some analysts have said, however, that Russia is at the limits of its capacity for launching missiles, having depleted its stockpiles and firing as many missiles as its industry can produce.

On Wednesday, Sabrina Singh, a Pentagon spokeswoman, said it was possible that Russia could fire another of a new type of intermediate-range ballistic missile, the Oreshnik, in the coming days. Russia fired an Oreshnik missile at a rocket factory in Dnipro in November after Ukraine began using American-provided missiles to hit targets in Russia.

Anastasia Kuznietsova contributed reporting.

In the days since the abrupt and unexpected obliteration of Iran as a dominant presence in Syria, the government has faced a fierce public backlash over the billions of dollars spent and the Iranian blood shed to back the Assad regime.

The criticism has come from unexpected corners, including conservatives, and is flowing freely on television channels and talk shows, and in social media posts and virtual town halls attended by thousands of Iranians. It also appears on the front pages of newspapers every day.

One former lawmaker, Heshmatollah Falahatpisheh, said in a social media post that Iranians should rejoice at the fall of Iran’s longstanding ally, President Bashar al-Assad of Syria. “No one will be able to waste Iran’s dollars for maintaining a spider web any more,” he said.

While opponents of the government have long bristled at the money Iran has sent all over the Middle East, the sentiment now seems to have spread. Even some who fought on their government’s behalf in Syria or lost family members in the civil war there are asking if it was worth it.

The Assad regime, some noted, was not the only loser to emerge from the uprising.

Ebrahim Motaghi, a professor of international relations at Tehran University, said on a talk show that Iran had been reduced from regional power to merely another country.

Some questioned the very foundation of Iran’s strategy over the past decades for making itself a dominant regional force that would confront Israel and its main backer, the United States: Tehran’s support for the array of militant groups across the Middle East that it called the axis of resistance.

In a front-page opinion piece in the newspaper Ham Mihan, a former Iranian representative to the intergovernmental Organization of Islamic Cooperation lashed out at his government. The defeat of Mr. al-Assad, wrote the cleric Mohammad Shariati Dehghan, exposed Iranian’s strategy as misguided and “built on weak foundations.”

Mr. Shariati Dehghan demanded a new approach that prioritized building alliances with countries instead of propping up militant groups, and redirecting money and resources back to the people of Iran.

The brash public debate is nothing short of extraordinary, given that for years Iranian leaders portrayed their support for Syria and allied militant groups fighting Israel as a nonnegotiable principle of the Islamic revolution and critical for national security.

“The Syria debate is happening at all levels of society, not just in the media and social media, but in daily interactions everywhere,” one prominent analyst, Hassan Shemshadi, said in a telephone interview from Tehran. “People are asking: Why did we spend so much money there? What did we achieve? What is our justification now that it’s all gone?”

Mr. Shemshadi, who is close to the government and until last year served as the head of the Iran-Syria Joint Chamber of Commerce, said that while the shape of future Iranian and Syrian relations was now uncertain, a strategic partnership built over four decades was now clearly history.

Gone, too, he said, is the unfettered access to supply routes in Syria that Iran had long had to equip militants across the region with weapons and other material.

The reaction from official Iran has been muddled.

President Masoud Pezeshkian and Foreign Minister Abbas Araghchi have sought to distance the nation from the events next door.

The Syrian people, the president and foreign minister said, have the right to determine their political future. The Iranian vice president for strategy, Mohammad Javad Zarif, said his country “stands ready to have good relations with the future government of Syria, and we have always stood at the side of Syrian people.”

But Iran’s supreme leader, Ayatollah Khamenei, in his first public address about events in Syria, took a harsher tone on Wednesday. He blamed the United States and Israel for Mr. al-Assad’s downfall, referring to the rebels who toppled him as “aggressors” with competing motives who were serving their masters. He also alluded to Turkey’s support for some of the rebels in Syria.

“By God’s blessing, the territories occupied in Syria will be freed by the brave young people of Syria,” Mr. Khamenei said. “Have no doubt that this will happen.” He predicted that the “resistance” would spread widely across the region, and Iran would grow stronger.

“God willing,” chanted the audience of several hundred men and women sitting on the floor in the visitor’s hall of his compound.

But Mr. Khamenei’s speech flew in the face of the reality on the ground in Syria, where the army quickly folded as the rebels advanced and Syrians — young and old, men and women — celebrated the downfall of a tyrannical ruler by dancing in the streets chanting, “Freedom.”

Even Hamas, the Gazan militants for whom Iran and its ally Hezbollah in Lebanon went out on a limb, issued a statement congratulating the Syrian rebels on their victory and declared it was standing with the Syrian people. Hamas had a brief falling out with Iran over a decade ago, when the Syrian uprising started, because each supported different sides.

Mr. Khamenei appeared outraged at the open criticism. The comments, he said, were “a crime” because they were sowing fear among the public. Within hours, Iran’s judiciary announced a criminal investigation into a list of prominent figures and news outlets that have been leading the criticism. The list included Mr. Falahatpisheh, the former lawmaker, who revealed that Syrian debt to Iran amounted to about $30 billion.

For over 40 years, Syria served, in effect, as Iran’s central command base in the region. Its access to territory, shipping ports and airports was so unimpeded that a senior military commander once described Syria as a province of Iran.

Iran controlled military bases, missile factories, tunnels and warehouses that served the supply chain for its network of militants. From Syria, Iran funneled weapons, cash and logistical support to Hezbollah in Lebanon, Hamas in Gaza and militants in the Israeli-occupied West Bank and Iraq.

“Syria was a linchpin to Iran’s regional plan, the encircling of Israel in a ring of fire,” said Matthew Levitt, director of the counterterrorism program at the Washington Institute for Near East Policy, a research organization. “The axis of resistance was a three-legged stool of Iran, Syria and Hezbollah, and it no longer stands. ”

Mr. Levitt said Iran also counted on Syria economically. Its purchases of Iranian crude and refined oil, despite U.S. sanctions on Iran, helped Tehran pay for its military operations in the region.

Five Iranian officials said that after Syria fell, many colleagues, reeling, privately disclosed that Iran had lost everything in just 11 days. The officials said the government was still “disorientated,” “befuddled” and trying to find a way forward with Syria.

The officials, including members of the elite Revolutionary Guards Corps who have spent time in Syria, insisted on anonymity because they were discussing sensitive matters. They said that Iranian leaders were now resigned to accepting any level of diplomatic presence, however small, that Syria’s new leaders allowed. Two of the officials said Iran was keen to avoid the embarrassment of being completely ousted from Syria, with diplomatic ties cut and its embassy there shuttered.

Mr. Araghchi, the foreign minister, said in an interview with state television on Sunday that Iran would base its next steps on the actions of Syria’s transitional leaders. He confirmed that Iran and the rebels had already exchanged messages, with the Syrians agreeing to requests that they protect Shia religious shrines and Iranian diplomatic outposts.

“Iran wants to move toward a direction that would eventually normalize its relations with Syria, but it’s going to be very difficult,” Rahman Ghahremanpour, a political analyst based in Tehran, said in a telephone interview. “The first priority right now is to make sure Syria does not turn into a base against Iran and a launchpad to attack its interests in Iraq or Lebanon.”

Mr. Ghahremanpour said the public reckoning that had erupted over Iran’s conduct in Syria could not be contained, and any official sugarcoating would not soften the severe blow. Some families of fighters killed when Iran deployed forces to Syria to help keep Mr. al-Assad in power are now asking if their loved ones had died in vain.

Alireza Mokarami, an Iranian veteran who fought in Syria’s civil war and now runs a local news site, posted a scathing takedown of Iran’s “catastrophic failure” in Syria in a widely circulated essay.

“Why were you spending billions of dollars of oil revenues that belong to the Iranian people on Assad until the very end if he wasn’t even listening to you?” he asked. He added, “At least on the topic of Syria, stop lying and be honest with the people.”

For the moment, the prospects of replicating the ties Iran once had with the Syria appear dim.

After the Assad regime was overturned, Syrians stormed the Iranian Embassy in Damascus, tearing down pictures of Iranian leaders and bringing down its flag. And Ahmed al-Shara, the Islamist rebel leader who spearheaded the insurgency, chastised Iran publicly.

The Assad regime, he said, brought many ills to his country — among them turning Syria into “a farm for Iranian greed.”

Leily Nikounazar contributed reporting.