A crowd gathers to hear a recorded speech from Hezbollah’s leader, Hassan Nasrallah, commemorating dead fighters. Hezbollah’s future is linked to Bashar al-Assad’s regime. “If Bashar goes down, we’re next,” a commander said.Photograph by Moises Saman / Magnum

The bodies of the two young fighters from Hezbollah were already in the ground when the memorial service began. They’d been killed days before, and their smiling portraits hovered above an outdoor stage in their village, Sohmor, in Lebanon’s Bekaa Valley. The stage was framed by huge banners, portraying Hassan Nasrallah, Hezbollah’s secretary-general, and Ayatollah Ali Khamenei, Iran’s Supreme Leader. In the portraits, the two fighters—Ali Hussein al-Khishen and Ali Mustafa Alaeddine—looked barely their age, nineteen. Khishen had chubby cheeks and a boyish smile; Alaeddine’s countenance was sterner and more knowing. “You are the proof of martyrdom!” one of the posters said.

The mourners, thousands of them, shuffled to their seats, the black-clad women drifting to the back. The atmosphere was not sombre but upbeat, undefeated, like a football stadium before kickoff. Boys in blue shirts and white kerchiefs—Mahdi Scouts—poured coffee from ornate decanters and handed out bottles of water. A Hezbollah brass band bleated out what sounded like a Sousa march. Khishen and Alaeddine were being celebrated in death.

At the time of the service, late last year, Hezbollah had spent months denying that its men were crossing the border into Syria to fight for Bashar al-Assad’s murderous regime. Yet evidence was mounting that they were. The day before the funeral, Syrian rebels announced that they had killed a Hezbollah commander and at least two of his men. Hezbollah acknowledged that the commander, Ali Hussein Nassif, had died, but refused to disclose where or how, saying only that he had been “performing his jihad duties.”

Like the fallen commander, the two dead fighters in Sohmor had been killed under murky circumstances. Hezbollah said that the two had died at an ammunition depot inside Lebanon, in an accidental explosion, four days before. But the service in Sohmor was a thikra usbu’, an Islamic ceremony held seven days after death. At the burial, the bodies of Khishen and Alaeddine had been kept inside their caskets, invisible even to their families.

The crowd stirred as guards began appearing on rooftops, clutching soft violin cases with the butts of machine guns poking out. Then a bearded man in a black turban walked onto the stage with his hands clasped, like a cleric. It was Hashem Safieddine, the head of Hezbollah’s Executive Council. The audience grew silent.

“Don’t cry, Sohmor,” Safieddine began. “You can’t have dignity without young blood.” He didn’t say how Khishen and Alaeddine had been killed, and he made no mention of an ammunition depot. Instead, he told the people that their sons had died for a noble cause, and that Hezbollah was built on sacrifices such as these. Then he talked about Syria. “We are more sure every day that the challenges we face from Israel, America, and the Arab countries are huge—and that the Arab countries are spending money to destroy Syria and Hezbollah,” he said.

Safieddine wasn’t exaggerating: after decades of belligerence, Hezbollah is surrounded by existential threats. In an Arab world dominated by Sunni Muslims, Hezbollah agitates on behalf of Shiite identity—forming, along with Syria and Iran, a column of resistance sometimes called the Shiite Axis. For thirty years, Syria has offered protection and facilitated a pipeline of money and arms from Iran. With Syrian and Iranian help, Hezbollah has become the most powerful force in Lebanon. Too strong to be challenged even by the government, it has set up its own mini-state and built one of the world’s most sophisticated guerrilla armies. It has kept up a relentless campaign to confront Israel, even provoking a war in 2006.

Now the civil war in Syria is threatening to break the axis. Without Syria, Hezbollah would have no bolster against its Sunni enemies, within Lebanon and throughout the region. Worse, it would be left alone to face Israel. In front of the crowd in Sohmor, Safieddine didn’t have to elaborate this point. He said only, “We are aware of what is happening in Syria, and we are courageous and more ready than ever for resistance.”

Back in Beirut, a Hezbollah officer conceded that the explanation for the young martyrs’ death—the explosion at the ammunition depot—had been contrived. They had been killed in Syria, he said: “There were a lot of bodies coming back.” It was something that no one was permitted to discuss, for obvious reasons: Hezbollah could not afford to anger Sunnis, but neither could it allow its allies in Syria to fall. “If Bashar goes down,” a Hezbollah commander told me, “we’re next.”

The Hezbollah commander, who called himself Dani (a pseudonym required to maintain his safety), met me in a private home around the corner from “the secure area,” a cluster of buildings that serves as Hezbollah’s headquarters in the southern Beirut neighborhood of Al Ghobeiry. Dani walked in wearing jeans, a tight black T-shirt, trail shoes, and a Quicksilver cap; his hair was short and his fair-skinned face was shaved clean. I was struck by his appearance, so unlike the cliché of an Islamic militant, and Dani did not fail to notice. “We’re not all bearded fanatics, you know,” he said. Dani, who is about forty years old, looked more like a good-natured auto mechanic, which he is, most of the time. One of eleven siblings, he is married and has two children of his own.

Dani grew up in a village within sight of the Israeli border, but, as he remembers it, his family had no anti-Israeli feelings. His father traded wheat and olives and often crossed over to buy and sell in the Israeli port of Haifa. “My dad had a lot of Jewish friends back then,” Dani said. “He didn’t think a lot about occupation.”

Throughout Dani’s childhood, the Palestine Liberation Organization was based in Lebanon. A Sunni-dominated group, it treated the Shiites harshly, and was an increasingly unwelcomed presence. Then, in 1982, the Israel Defense Forces poured across the border, in a huge military operation aimed at destroying the P.L.O., and soldiers made their way to Dani’s village. At first, the villagers, like many Lebanese, welcomed the Israelis, whom they hoped would rid them of the P.L.O. “I ate the candy they threw us,” Dani said. But it wasn’t long before Israeli soldiers began to sweep the region’s Shiite villages for weapons, detaining men with no connection to the P.L.O. Soon Dani needed written permission from the Israelis to move in and out of town. “They made us prisoners in our own country,” he said.

Ever since the nineteen-twenties, when the colonial French carved Lebanon from the remnants of the Ottoman Empire, it has been a political playground for its more powerful neighbors: Israel, Syria, the Palestinians, and Saudi Arabia, each of which has routinely manipulated Lebanese politics through local proxies. Lebanon’s vulnerability lies in its intense polarization, which has bedevilled every government that has tried to run the place. The country was intended by the French as a kind of sanctuary for Maronite Catholics. Over time, the Catholics and other Christians, who were once a majority, clung to power even as they were surpassed in numbers by Muslims. Now eighteen officially recognized religions and sects thrive among four million people, in a country the size of Connecticut. Sunnis, Shiites, and Christians predominate, but none has a majority. In 1975, sectarian tensions, aggravated by the growing militancy of the P.L.O., exploded into a civil war. The war lasted fifteen years, devastated the country, and killed a hundred and twenty thousand people. In the midst of the war, in 1982, came the Israeli Army.

As Dani looked for a way to resist the invaders, the obvious option, the Lebanese Army, was closed. The Army—indeed, most of the government—had all but ceased to exist. Then a new group arose, dedicated to opposing Israel; it was known as Hezbollah, from the Arabic for “Party of God.” The group dates its beginning to November 11, 1982, when a teen-ager named Ahmad Qassir approached the Israeli headquarters in Tyre and blew himself up. Its true origins aren’t so simple. Hezbollah emerged from a collection of disparate armed groups, but almost immediately the fighters began receiving training, direction, and money from Iran’s Revolutionary Guard. “The Iranians were looking for an opening in Lebanon, and the Israeli invasion gave it to them,” David Crist, a historian for the U.S. government and the author of “The Twilight War,” an account of the American-Iranian rivalry since 1979, said. “The Iranians’ great success is that they took all these disparate groups that were fighting the Israelis and brought them together.”

The Iranian regime spent as much as two hundred million dollars a year supporting Hezbollah, according to a U.S. Defense Department report. For Iran, Hezbollah was an appealing proxy. Like the Iranian regime, it was composed of Shiites, a minority throughout most of the Islamic world and historically its downtrodden class. Hezbollah’s founders, adhering to the doctrine of wilaayat al faqih, recognized Iran’s Grand Ayatollah as the leader of the global Islamic revolution. But mostly the Iranians wanted Hezbollah as an advance force to confront Israel. In Hezbollah’s first manifesto, published in 1985, its leaders proclaimed their dedication to fighting until Israel was “obliterated.” Paul Salem, the director of the Carnegie Middle East Center, in Beirut, said, “Hezbollah is an Iranian aircraft carrier parked north of Israel. ‘You hit us, we hit you.’ That is what Hezbollah gets the big bucks and the missiles for.”

Among the fighters in the early days was Hassan Nasrallah, a round-faced cleric whose magnetism captivated almost everyone he met. Nasrallah, then in his early twenties, was a son of Karantina—“the Quarantine”—one of the most impoverished neighborhoods in Beirut. His father sold fruit from a pushcart. He was an avid reader of theology as a boy, and he later attended the fabled Shiite seminaries of Najaf, in Iraq, and Qum, in Iran. In 1992, Israeli forces assassinated Abbas al-Musawi, the leader of Hezbollah, by firing a missile at his car. Nasrallah took his place, only months after returning from Iran.

Soon after Hezbollah was founded, Dani, though still a boy, left home and joined. “I vowed never to return to my village until it was liberated,” he said. Over the next eighteen years, Hezbollah waged a guerrilla war against Israeli soldiers who occupied southern Lebanon. Dani fought all the time. “I became a soldier,” he said. American troops came in to help the Lebanese government, and Hezbollah struck against them as well. According to U.S. officials, two of the bloodiest attacks against Americans in the nineteen-eighties were carried out by Hezbollah operatives with Iranian support: the suicide attack on the American Embassy in Beirut, in April of 1983, which killed sixty-three people; and the truck bombing of Marine barracks that October, which killed two hundred and forty-one Americans. (Hezbollah has denied involvement in either attack.) In 1985, Hezbollah militants kidnapped Colonel William R. Higgins, an American officer overseeing United Nations peacekeepers on the Israeli border, and tortured him to death. “We were under military occupation at the time, as far as I see it, and so therefore I don’t think those were terrorist attacks,” Dani said.

A few days after we first spoke, Dani took me on a tour of southern Lebanon, where war with Israel festered for decades. We drove south out of Beirut, along the Mediterranean coast, past Sidon’s sea castle, the stone fortification built by the Crusaders in the thirteenth century, and through the ancient city of Tyre. “All of this,” he said, pointing out the window, “used to be in Israeli hands.” Martyrdom posters lined the roadside, along with other indications that Hezbollah was governing the place. “Hezbollah welcomes the Pope!” one poster said.

We stopped in a village, at a café called Al Bas, where a young man who introduced himself as Hussein Hodeh was standing behind an espresso machine. When I asked him about the village’s allegiances, he shrugged and said, “It’s a Hezbollah town.” I asked how he knew, and he reached under the counter and unfurled a yellow Hezbollah battle flag. “I’m Hezbollah myself,” he said, with a laugh. “I’m a fighter.”

“Maybe I’m too big to fail, but I’m not too big to have my feelings hurt.”

About ten miles from the Israeli border, we turned inland, moving across a hilly landscape of limestone bluffs and olive trees. Dani pointed out landmarks. “That bridge—the Israelis used to bomb it all the time,” he said. After a while, we reached Mleeta, a fantastical theme park dedicated to Hezbollah’s triumphs, and pulled into a parking lot next to a tour bus. In the nineties and again in 2006, Israeli soldiers and Hezbollah militiamen fought for the ground on which Mleeta sits, and the battlefield has been preserved, in the manner of Normandy or Gettysburg. The grand opening, in 2010, was attended by a representative of the Lebanese Prime Minister. Down a path from a gift shop that sells Hezbollah T-shirts and coffee mugs adorned with Nasrallah’s face, Dani pointed into a wide pit and said, “This is the destroyed Israeli tank.” There lay the carcass of an enormous Merkava, Israel’s finest, its bottom blown out by a bomb and its barrel tied in a knot. It was surrounded by a small sea of Israeli helmets. “It’s all real here, all real,” Dani said. “I know—I remember.”

We walked past a tunnel network and an array of Katyusha rocket batteries, alongside a group of European tourists snapping photos. Here and there, Dani paused. “The Israelis were right here,” he said. “Sometimes they would advance, sometimes we would advance. Sometimes the fighting was face to face.” Dani spoke with predictable contempt for Israel. “It’s a cancer,” he said. “It’s a parasite.” But he had nothing but admiration for the soldiers he had faced in battle. “The Israeli fighters are very fierce and very brave. They knew every inch of this ground, better than we did. We respect them. We don’t take them lightly. That’s why we were able to beat them.”

Everywhere in Mleeta there are placards and inscriptions, all with the same theme: before Hezbollah, there was nothing but humiliation. “From 1948 until the invasion of Lebanon, in 1982, the Israeli enemy imposed on Lebanon and the region only one choice,” one of the placards said. “Surrender, defeat, and subjugation.” Hezbollah, the sign went on, “announced the birth of a different course: Resistance.” In 2000, the last Israeli troops withdrew from southern Lebanon. Dani went back to his village, which his relatives had fled. “I was the first one from my family to enter our village,” he said.

Nasrallah gave a speech in the Hezbollah stronghold of Bint Jbeil that was triumphant and anti-Zionist, if not overtly anti-Semitic. “We must acknowledge the grace of the fighting, the resisting and the sacrificing of the people who left their homes, families, and universities,” he said. With the Israeli withdrawal, Nasrallah became a hero in Lebanon and throughout the Arab world. “Nasrallah’s legitimacy in the Shiite community is almost unquestioned,” Salem, of the Carnegie Middle East Center, told me. “He is one of those historic figures, like Nasser in Egypt, whose identity merges with the people. He’s a messiah figure.”

When I asked Dani what Iran and Syria were doing in Lebanon, he went quiet; the subject is taboo in public and in the press. He would say only, “Assad is our friend; we don’t deny that. If he goes down, it’s bad for us.” On the Syrian civil war, Dani held to the Hezbollah line: it was true that Bashar didn’t treat his people well—“We recognize this,” he said—but the real trouble in Syria was caused by Western nations that were backing the rebels in order to take pressure off Israel. Yet the prospect of a Sunni majority, even a fundamentalist regime, coming to power in Syria was so alarming that at one point Dani seemed to be siding with Israel. “You wait and see,” Dani told me. “You’re going to have Salafists in Syria attacking the Golan Heights. What are you going to do then?”

It was clear that Hezbollah’s leaders had concluded that any change in Syria was almost certain to wash across the border, and that they were getting ready. “If the Sunnis take over Syria,” Dani told me, “we’re going to be fighting them in Beirut.”

To better understand the link between Hezbollah and Syria, I paid a dinner visit to the Beirut home of Walid Joumblatt, the leader of a tiny religious group, the Druze, and perhaps Lebanon’s most nimble and sophisticated politician. Joumblatt is an unprepossessing man—with a bald head, weary eyes, and a tiny mustache, he looks like a latter-day Edgar Allan Poe. But, with his small bloc of parliamentary seats, he has spent his career moving from one faction to another, making and breaking Lebanese governments.

We dined on ‘assafeer, roasted larks so small that you don’t need to remove the bones, and Joumblatt reached frequently for a decanter of sake. His dining room was filled with books; on a side table sat a copy of “Description of Egypt,” Napoleon’s attempt to catalogue Egypt’s archeological history. Oscar, Joumblatt’s Shar-Pei, was underfoot. “My best friend,” he said.

As Joumblatt told it, the Syrians had destroyed his family, and afflicted his country for decades. The Syrian Army first rolled across the border in 1976, in the early part of the Lebanese civil war, on the pretext of restoring order. But, as the civil war continued, the troops remained. Led by Hafez al-Assad, and then his son, Bashar, the Syrians dominated Lebanon’s society and its economy, extracting billions of dollars in tithes, bribes, and drug money. The Assads intervened regularly in Lebanon’s democratic political system, often calling on local proxies to carry out assassinations. Joumblatt’s father was the first. In March of 1977, Kamal Joumblatt, then the leader of the Druze, was shot dead as he was driving home. His militia had been resisting the Syrian troops, and the suspicion has always been that Hafez al-Assad ordered the killing.

Walid, then twenty-seven, took over as leader and, barely a month later, found himself sitting next to Assad. “I still had some hair—I was not yet bald—and Hafez looked at me and said, ‘How strange, you look like your father,’ ” Joumblatt told me. “I was hiding my anger. I had to do it for the sake of my community. I had no choice but to fix up a pact with the devil. So I shook hands with this man. I looked at him. And he did not move—he was known not to move, like a pharaoh.” Joumblatt sighed. “Lebanon is not an independent country. We have the sea, we have Israel, and we have Syria.”

In the nineteen-eighties, Syria’s relationship with Hezbollah was strained, and sometimes devolved into street fighting. But when the civil war ended, in 1990, Hafez al-Assad decided to allow Hezbollah to carry on its fight against the Israelis and to use the group as a local ally. For Hezbollah, an alliance with the Syrians meant that it could go on building its military without interference from the Lebanese government.

Over the years, growing numbers of Lebanese came to regard the Syrians as overbearing and exploitative—an inland relative bullying and mooching off a smaller, more sophisticated cousin. Around 2000, Rafik Hariri, a two-time Lebanese Prime Minister and a charismatic businessman with ties to the Saudi royal family, began trying to pull the country out of Syria’s orbit. In August, 2004, Hariri visited Damascus, where Bashar al-Assad warned him that his efforts were putting him in grave danger. “We will break Lebanon,” Bashar said. When Hariri returned to Lebanon, according to Joumblatt, who was a close friend of his, “he said, ‘Either Bashar is going to kill me or he is going to kill you.’ He was resigned to fatalism. God decides. And it happened.” On February 14, 2005, Hariri was driving along the Corniche, Beirut’s spectacular coastal drive, when a suicide truck bomber crashed into his motorcade. He and twenty-two others were killed.

For Assad, the murder of Hariri appeared to be a routine act of political manipulation. But, instead of quashing Lebanese desires for independence, the killing intensified them. Hundreds of thousands of Christians and Sunni Muslims poured into downtown Beirut to demand an end to the Syrian occupation. (Across town, Hezbollah staged enormous rallies of Shiites calling for the Syrians to stay.) In April of 2005, as outrage over the assassination grew—and as pressure mounted from the United States and the United Nations—Syrian troops departed, ending the occupation after twenty-nine years. “The Syrians came in on the blood of Kamal Joumblatt and left on the blood of Rafik Hariri,” Joumblatt said.

Hezbollah, with its protector gone, was forced to make an uncomfortable move: it got into government. The group had been fielding candidates for parliament since 1992, but only reluctantly, as members insisted that their first duty was to confront Israel. Hezbollah’s parliamentarians have learned to play politics—Nasrallah has dropped the sectarian language of his predecessors and stopped deploying suicide attacks—but they still stand apart. In the national assembly, they typically huddle across the floor from their fellow-Shiites in the Amal Party, whose Westernized members talk freely with women and drink alcohol. And they do not speak without permission from their leaders. (None were willing to coöperate with this article.)

After the assassination of Hariri, Lebanon split into two camps: an anti-Syrian faction led by Hariri’s son, Saad; and a collection of pro-Syrian groups, including Hezbollah. The anti-Syrian faction has taken an increasingly aggressive position toward Hezbollah, demanding that the group give up its weapons and become an ordinary political party. Hezbollah has resisted, sometimes violently. The result has been near-perpetual crisis. In 2008, the Lebanese government, led by the Hariri bloc, voted to outlaw Hezbollah’s private communications network. Within hours, Hezbollah gunmen fanned out across western Beirut, precipitating clashes with Christians and Sunnis that left scores dead. As the violence raised fears of outright sectarian war, Hezbollah and its allies struck a deal that gave them far greater representation in the government. “Hezbollah is in government to make sure there is no decision to take away their arms,” Alain Aoun, a member of the Lebanese parliament and a coalition partner of Hezbollah, said. “This is their main concern.”

The Hariri assassination continues to haunt Hezbollah. Both the Bush and the Obama Administrations believe that Assad was deeply involved, and that he used Hezbollah to help. In 2005, Lebanon detained the heads of four of its security agencies—regarded as Syria’s close allies—for their alleged involvement; they were held for nearly four years and released. Then, in June of 2011, a tribunal backed by the U.N. indicted four members of Hezbollah. According to the indictment, the Hezbollah operatives served as spotters as Hariri’s car drove along the Corniche. Investigators were evidently led to the men because one of them made a cell-phone call to his girlfriend during the stakeout.

Hezbollah insists that the tribunal is biased and invalid. In 2011, with Hariri’s anti-Syrian faction in control of the government, Hezbollah demanded a meeting to discuss the investigation. When Hariri refused, Hezbollah and its allies in the cabinet orchestrated the collapse of the government. “They wanted a government that was not against them on this issue,” Aoun said. After months of negotiation, Hezbollah’s bloc, which already had a large number of parliamentary seats, controlled a majority of the cabinet; Hezbollah members were charged with overseeing the agriculture ministry and the reform of the Lebanese bureaucracy.

Dani told me, “The only reason we get into politics is because we have to. But we hate politics—we hate it.” And yet Hezbollah has found itself charged with such mundane duties as delivering electricity and collecting garbage. “Running a government is not their primary concern,” Mohamad Chatah, a senior member of Hariri’s party and a former ambassador to the United States, said. “Obviously, their stature comes primarily from the battlefield and their hostility to Israel, but their success in doing other things adds to their support, and they have been generally good at doing other stuff. But you have to remember that Lebanese standards are not very high.”

Hezbollah’s emergence as a force in Lebanese politics has put the Obama Administration in a difficult spot. Since 1997, the United States government has deemed Hezbollah a terrorist organization, and thus off limits to American diplomats. In January of 2011, a new Prime Minister, Najib Mikati, who has Hezbollah members in his government but is not affiliated with the group, took office. Officials with the Obama Administration have met with him but not with his Hezbollah partners.

“Let’s not forget who wears the plumage in this family.”

As Hezbollah solidifies its official power, anxiety over assassination still permeates Lebanon’s political class. In April, Samir Geagea, the leader of a Christian party known as Lebanese Forces, narrowly survived a sniper attack while strolling outside his house. No one could prove anything, of course, but many people I talked to assumed that Hezbollah agents, working with Syrians, carried out the attack. In October, General Wissam al-Hassan, a senior intelligence official and an ally of the United States, was killed by a car bomb in Beirut. Hassan had led the investigation into Hezbollah’s role in Hariri’s killing, and had recently ordered the arrest of a pro-Syrian politician named Michel Samaha, for trying to smuggle explosives into Lebanon at the behest of Syrian intelligence. “We think Hezbollah did the killing,” an Israeli official told me. “They are the only ones with the motive and the technical sophistication.”

When I pressed Joumblatt about who might be carrying out the assassinations, he gave me a weary look. “Look, I am not now, morally speaking, someone who is entitled to give lessons,” he said. After his father’s murder, he became one of the most ruthless commanders in Lebanon’s civil war, presiding over shelling in Beirut and sectarian killings. “I was a warlord. My people committed crimes, under my command, sometimes obeying orders, sometimes not obeying orders. Because it was a civil war. War is horrible, but civil war is something worse. I am also someone who has a black past.”

Now, Joumblatt told me, he, too, was worried about his safety. But, despite having lost his father and his friend Hariri to assassination, he wasn’t doing much to protect himself. “I have some guards here,” he said. “But these people—they have the technology to kill you even inside your own home.”

At Wadi Naim, three miles from the Israeli border, a vast Hezbollah bunker complex is hidden in a valley wall, camouflaged by limestone and bush. It’s invisible from the road, two hundred feet below, invisible from the air, invisible even to the visitor standing on top of it. The only way to find it is by using a G.P.S. programmed with the precise coördinates. Under a foot of dirt and rubble is a trap door, and a ladder leading down to the main tunnel. Inside, the only sign of life was a colony of black bats, dangling silently from the ceiling. Startled by my entry, they dropped down, then glided up the shaft toward the light.

Underneath the limestone, the bunker is supported by walls of reinforced steel. There was a kitchen, a bathroom, and space for twenty people to sleep. Standing inside, a hundred feet underground, it was not difficult to imagine a group of Hezbollah fighters sitting out a bombardment for days, even weeks, the Israelis unaware of their location or unable to penetrate it.

In July of 2006, Nasrallah ordered his men to stage an attack inside Israel. They captured a pair of soldiers, and, for the next thirty-four days, the Israel Defense Forces mounted an enormous response. Israel killed scores of Hezbollah’s men and destroyed its headquarters and its supply network. The attacks killed as many as twelve hundred Lebanese civilians, flattened entire blocks of southern Beirut, and destroyed many of the roads, bridges, and public buildings in southern Lebanon.

Yet Hezbollah mounted a fierce resistance, from bunkers like the one in Wadi Naim, where fighters emerged to attack with wire-guided missiles and quickly ran back inside. At the same time, thousands of Hezbollah rockets rained down on Israel from batteries hidden in forests, fortified garages, and even people’s homes. The result was a bloody draw—a revelation to the Israeli Army, accustomed to dominating wherever it fights. General Dan Halutz, the I.D.F.’s chief of staff, resigned during an investigation that identified “grave failings” in his generals’ prosecution of the war. Just how Hezbollah fighters were able to build bunkers such as the one I visited in Wadi Naim has never been fully explained. “Hezbollah will not surprise us again,” Ehud Barak, Israel’s Defense Minister, has said.

For Nasrallah, the war was both a victory and a catastrophe. Shortly after a ceasefire was arranged, he said that he would never have ordered the initial operation had he known that it would lead to war—“absolutely not.” He was nearly killed himself. Halutz told me that Israel had twice sent jets to attack bunkers where Nasrallah was thought to be hiding. “The first time, we had the right place but he was very deep underground,” he said. “The second time, he wasn’t there. The third time, we won’t miss.”

But when the war was over Nasrallah’s status was higher than ever. Israeli soldiers returned from the front lines stunned by the prowess of the Hezbollah fighters, who were sometimes equipped with night-vision goggles and sophisticated eavesdropping equipment. On the first night of the conflict, a Hezbollah missile struck an Israeli destroyer off the coast. Hezbollah fighters destroyed Merkava tanks and killed a hundred and twenty-one Israeli soldiers. “This was a strategic, historic victory, without exaggeration,” Nasrallah said in a televised speech. “We emerged victorious, where Arab armies had previously been defeated.”

Another thing that helped take the sting out of the Israeli assaults was Iranian money. At extraordinary expense, south Beirut and southern Lebanon were rebuilt; it is difficult these days to find a building that shows damage from the war. According to a Lebanese security official, the reconstruction was financed largely by Iran, which bypassed the Lebanese government. In the months after the ceasefire, Hezbollah trucks pulled into devastated neighborhoods and handed out Iranian money to Lebanese who’d lost property and kin. The security official said that the Iranians poured between two and three billion dollars into the country; the money was transported by air to Syria, he said, and then “they brought American dollars on trucks from Damascus.”

As I drove through southern Lebanon with Dani, he pointed to freshly paved roads and newly built hospitals. “Iran paid for all of this,” he said. “If we had been forced to rely on the Lebanese government, this area would still be in ruins.” Iranian money is the crucial means by which Hezbollah militants have cemented support in the Shiite community. In southern Beirut, I met a man who identified himself as Ahmed Shah, a shop owner and father of two who lived a few blocks from Hezbollah’s headquarters. For fifteen days in 2006, Shah and his family rode out the Israeli bombardment, feeling the building shake day and night, until they finally decided—like hundreds of thousands of other Lebanese—to flee. Shah moved his family to an apartment on the Christian side of the city, which the Israelis spared. When he returned, three weeks later, he found his neighborhood demolished. “A missile cut my building in half,” he said.

Shah was seated at a picnic table, drinking tea with friends. Behind him was his rebuilt apartment, paid for almost entirely by Hezbollah. The day the war ended, Shah said, Hezbollah men began walking through the neighborhood, surveying the wreckage and handing out cash. A few days later, Shah met a group of Hezbollah administrators, who laid down the terms: at a cost of forty thousand dollars, they would rebuild his apartment, and they would give him five hundred dollars a month to rent an apartment for the next year and a half. The Hezbollah administrators gave Shah ten thousand dollars more to furnish the new place. Shah figured that the Lebanese government paid for perhaps a quarter of the reconstruction, but even that money was distributed by Hezbollah.

“Everyone supports Hezbollah here—it is the only government we have,” Shah said, as his friends at the table nodded. “We don’t mind that the Iranians are paying for everything.” I asked Shah if his allegiance to Hezbollah wasn’t costing him his neighborhood. Hezbollah started the war, after all. He shrugged. “It happened in 1982, 1985, 1994, 1996, 2000, and 2006,” he said. “Every few years, this neighborhood is destroyed, usually by Israel.” His friends nodded again. “It’s about that time again.”

In late January, the Israelis struck a convoy in Syria that they said was carrying anti-aircraft missiles to Hezbollah—missiles that could make it more difficult for Israeli aircraft to fly unhindered over Lebanon. Shortly after that, a senior commander of the Iranian Revolutionary Guard was killed as he crossed the border into Lebanon; no one claimed responsibility, but Hezbollah accused Israel. Both Hezbollah and Israel are preparing for the next war—and it promises to be far more devastating than the previous one. In 2006, Hezbollah fired an estimated four thousand rockets and missiles into Israel. This time, according to American officials, Hezbollah’s arsenal stands closer to fifty thousand projectiles, many of which have ranges long enough to strike every major city in Israel. The longer ranges have allowed Hezbollah to disperse its missiles across the country—all but insuring that an Israeli response would destroy areas far outside southern Lebanon.

Israelis expect that any war with Hezbollah is likely to be short. Foreign leaders, from the United States and elsewhere, will try to bring fighting to a quick end, which gives both sides an incentive to inflict as much damage as possible before a ceasefire. In Lebanon, I was told repeatedly that Hezbollah could be drawn into war if Israel attacked Iran’s nuclear-enrichment facilities. Last year, Nasrallah threatened that, if Israel struck Iran, American targets would be attacked. “A decision has been taken to respond, and the response will be very great,” he said in a television interview. “American bases in the whole region could be Iranian targets. . . . If Israel targets Iran, America bears responsibility.”

If Hezbollah joined in such attacks, it would be catastrophic for the state of Lebanon. After the 2006 war, Israel announced the Dahiya Doctrine, which an Israeli official explained as “Lebanon is Hezbollah and Hezbollah is Lebanon. Hezbollah shoots at us and we go to war against Lebanon.” Some Lebanese believe that Hezbollah is ultimately more loyal to the Ayatollah than to its home country. “It’s the third time in history that the Persians have been on the shores of the Mediterranean,” Joumblatt said. “You have a community dominated by Hezbollah, well entrenched in Lebanon, with a formidable arsenal, and supplies and ammunition and money that are huge. You have to sit and talk with them, but what do you say? They don’t decide. It’s Khamenei and Ghassem Soleimani who decide,” he said, referring to the Supreme Leader and a powerful Iranian official in the Revolutionary Guard. “It’s beyond Lebanon.”

Halutz, the Israeli commander, believes that Hezbollah’s leaders would not necessarily respond if Israel attacked Iran. “They will wait and see the first results,” he said. “If their partners are not successful, then they will not join. They will not bet on a losing horse.” When I asked Dani about this, he said his leaders assumed that they didn’t have to waste time wondering whether they would fight on Iran’s behalf. “If the Israelis attack Iran, then they will attack us, too,” he said.

Even if there is no war, Hezbollah could lose its main link to Iran if the Assad regime falls. Nearly all of Hezbollah’s war-making material—missiles, money, and ammunition—travels through Syria. The group is already scrambling to find new supply lines. Still, the Lebanese security official said that losing Assad would be a grave blow. “Right now, Hezbollah has enough missiles for one more war—a big war—but then all their weapons are gone,” he said. “When that happens, if Assad is gone, then life will be very hard for Hezbollah. They will have to change. They will have to moderate their behavior. They will have to put away their dreams.”

In the opaque world of Lebanese politics, one path to understanding lies in the study of Hassan Nasrallah’s face. When he was younger, Nasrallah gave off the hard stare of a soldier sure of his aim. As Hezbollah grew, his features softened; he donned wire-rimmed glasses and his beard turned gray, giving him the aspect of a slightly mischievous shopkeeper. Since the war in 2006, Nasrallah has lived almost entirely indoors, often in concrete bunkers, venturing out rarely, lest the Israelis try to kill him.

“Miss Perkins, I need more lumbar support.”

In October, Nasrallah appeared on Lebanese television, and the uprising in Syria seemed to have changed his face again. It was rounder, puffier, paler—the face of a man who is not only hunted but alone. Seated in front of a bright-blue background, he wore fashionable glasses, a trimmed beard, and the black turban that indicates presumed descent from the Holy Prophet. He started by talking about a pilotless drone that Hezbollah had sent over Israel. The drone, designed by Iran and assembled by Hezbollah technicians, had made it nearly to Dimona, a city in southern Israel that is believed to contain that country’s nuclear facilities, before it was shot down. Nasrallah broke into a smile. The Israelis, he said, were “perplexed” by Hezbollah’s ability to carry off such a sophisticated stunt. “The Lebanese should be proud that they have young men with such brains!” he said. For a moment, Nasrallah seemed his old self. Then his smile vanished, and he said he wanted to talk about reports in the Lebanese press that Hezbollah men were fighting in support of Assad.

The issue of Hezbollah’s role inside Syria raises fundamental questions about its identity and purpose. Is it really a “resistance” organization, dedicated only to fighting Israel? American and Lebanese officials say that Hezbollah fighters are indeed helping the Assad regime in Syria, mainly by advising Syrian fighters. The Hezbollah operatives are working close to the front lines and may be fighting themselves, the American official said. (He added that Iran prefers Hezbollah agents because they speak Arabic, as do the Syrian fighters.) Most Lebanese I talked to took it for granted that Hezbollah operatives were helping prop up Assad, for obvious reasons of self-interest.

Siding with the Assad government has already left Nasrallah alone in the Arab world. In 2011, an American official told me, he went to Damascus to try to persuade Khaled Meshal, the leader of Hamas, to support the Syrian regime. Hamas had been an ally of Assad’s and, like Hezbollah, the recipient of extensive support from Syria and Iran. According to the official, who had knowledge of the meeting, Nasrallah reminded Meshal of their obligation to the Iranian government and pressed him to back Assad. Meshal refused, and shortly thereafter broke publicly with Syria.

In Nasrallah’s televised speech, he mentioned Lebanese news reports of secret Hezbollah funerals for fighters killed there; he spoke of one report saying that seventy-five of his fighters had been killed in a Syrian village called Ribleh. And he mentioned the Free Syrian Army’s claim that a Hezbollah commander had been killed inside Syria. Nasrallah spoke glowingly of the dead: “Dear, chaste holy martyrs!” Then he denied it all. The reports were cooked up by enemies, he said. A number of Hezbollah fighters had been killed, but they were actually Lebanese along the Syrian border, who had come under unprovoked attacks from the rebels. “This has nothing to do with fighting alongside the government,” he said. “This is truly what took place.”

The explanation seemed tortured, even ridiculous, but Nasrallah went on, his eyes narrowing and his mouth tightening. He said that the Lebanese government would not know how to protect its citizens. “What shall we do?” he said. “O our state, our government, our Lebanese parties, our political leaders, and our political and religious authorities!” By the time he brought his speech to an end, every trace of his boyish charm had departed. “Finally, I will say, Let no one bully us. Let no one try us.”

A few days later, I drove to the town of Arsal, on the Syrian border. As I approached, the civil war came into full view: a fight was on for possession of a border post held by the Syrian government. A Syrian gunship circled overhead. Explosions thundered in the distance.

The Masharia mosque, a half mile inside Lebanon, had Hezbollah flags flying, and an ambulance parked outside. Syrian refugees in Arsal told me that Hezbollah members were making regular trips across the border. “They pick up their wounded and bring them back here,” one refugee, who was camped nearby with his family, told me.

Not far from the scene of the battle, I met a mid-level commander in the Free Syrian Army, whose nom de guerre is Abu Bakr. He looked exhausted from months of fighting inside Syria, but his beard was neatly trimmed. Over coffee at his home in Arsal, Abu Bakr told me that he was a Lebanese Sunni—not a Syrian citizen. He was fighting out of solidarity with his fellow-Sunnis, who were resisting the Assad regime across the border. He said he felt confident that the rebels would prevail, but that the fighting he’d been in was horrendous. “They are being slaughtered,” he said of the rebels.

Abu Bakr understood Hezbollah operatives to be playing a significant role in helping the Assad regime, especially in training the shabiha, Assad’s brutal militia. He said that he had interrogated Hezbollah prisoners who were captured inside Syria, and that he had regularly tracked fighters as they crossed from Lebanon. A week before we spoke, comrades in Lebanon had radioed ahead that a Hezbollah convoy was heading to the border. As soon as the convoy crossed into Syria, Abu Bakr and his men struck. “We killed nine Hezbollah fighters,” he said.

The decision to wait until the convoy had entered Syria was an obvious one, Abu Bakr said. The fear of all Lebanese living along the border is that the war in Syria will spill over. So far, he said, it has not, but, the longer the war goes on, the greater the chances that it will. “We hope this will not happen, but everyone is worried about it,” he said.

On a recent Friday morning in Sidon, a crowd of three thousand Sunnis gathered at the Bilal bin Rabah mosque. They had come to hear Sheikh Ahmed al-Assir, one of the country’s best-known Sunni preachers. Sidon is a Sunni-majority city in a region dominated by Hezbollah. In recent months, as the Syrian civil war has taken on a sectarian character, Sunni-Shiite tensions have risen in Sidon, and Assir’s sermons have become inflamed. He is a striking figure: tall and thin, with an enormous wiry beard, which he sometimes sets off with black wraparound sunglasses.

Assir began by telling his listeners what was happening to Sunnis in Syria. “Just watch your television,” he said. “Children are being killed, mothers are crying, destruction is everywhere. Our people and our mosques are being destroyed in Syria.

“We should sympathize with the Syrian revolt on the basis of our religion,” Assir said. “For forty years, the Sunnis in Syria have been stepped on and humiliated. Ask yourself: What am I doing? We are asking you to support the Muslims of Syria.” Assir moved to a more delicate subject. “You know, Hassan Nasrallah says he is not involved in Syria,” he told the crowd. “And he is a liar! They rape women. They are slaughtering our children.” Hezbollah’s attempts to hide its role in Syria were preposterous, Assir said. “It is too big.”

Assir ended his sermon by turning to Lebanon. The struggle engulfing Syria was coming home, he said; the Sunnis of Lebanon have been oppressed no less than the Sunnis of Syria. Already, Assir said, Shiites under Hezbollah’s leadership have persecuted the Sunnis of Sidon, depriving them of municipal services and jobs, turning their neighborhoods into garbage dumps, attacking them and killing them without provocation. As the Sunnis rose against Assad, Assir said, so they will rise against Hezbollah. “Who has enslaved us in Lebanon for years? Who has been blackmailing us? Who killed Rafik Hariri?” he asked. “The same criminal!”

Since the civil war ended, in 1990, the Lebanese political system has relied on an exquisite balance among the main groups, and on a measure of self-restraint on the part of each. Hezbollah, with the help of its Iranian and Syrian benefactors, has pushed and sometimes broken the limits of the Lebanese system. The question for the future may be whether Hezbollah can restrain itself if it is threatened with a diminishment of its power.

The situation could come to a head during parliamentary elections in June, and many Lebanese predict that voters will return Saad Hariri’s anti-Syrian group to power. “If they win, and the Assad government is gone, then I imagine they will try to disarm Hezbollah,” Amal Saad-Ghorayeb, a Lebanese writer close to Hezbollah’s leaders, said. “Hezbollah would be forced to defend itself.” When I asked Dani what the consequences might be, he didn’t hesitate: “There would be civil war.”

In the northern Lebanese city of Tripoli, sectarian violence has broken out between Sunnis and an enclave of Alawites, killing dozens of people, but the fighting has not spread. For the moment, Joumblatt told me, a civil war is not likely, if only because Hezbollah is too strong to be challenged. “It would be suicidal to go to war with Hezbollah,” he said. Joumblatt believes that Hezbollah will one day transform itself entirely into a political party, but not anytime soon. “The calculation is that, once Bashar is gone, then Hezbollah will be weakened. But I don’t see it. They might be weakened, but, at the same time, they are still here, with their fifty thousand missiles. It took the British twenty years to persuade the I.R.A. to decommission its weapons. Here I think it will take centuries.”

Still, there are signs that Hezbollah, squeezed by the war in Syria, is beginning to cede some power. After joining the government, in 2011, Hezbollah deputies consented to fund the U.N. tribunal investigating Hariri’s murder—the same tribunal that had indicted Hezbollah’s operatives. Hezbollah has stood by while the new Prime Minister cultivated a relationship with the United States. The group has shown remarkable flexibility in negotiations over the drafting of a new electoral law, which could transform the composition of the Lebanese parliament. And, in September, Nasrallah agreed for the first time to allow the Lebanese Army to enter southern Beirut to restore order. “Domestically, they are being very compliant,” Basem Shabb, a Christian member of parliament, said. “Hezbollah’s absolute domination of Lebanon is not what it used to be. And it will only get harder.”

Dani got out of his car and looked across the border into Israel. The line between Lebanon and Israel is among the most surreal international boundaries in the world. The implacability of the dispute is surpassed only by each country’s need for space. And so, in place of rows of barbed wire and minefields, there is a single chain-link fence on the Israeli side and an occasional cement wall on the Lebanese. From where Dani stood, the Israeli soldiers were close enough to talk to. Israeli homes are a hundred yards away. A long paved road runs along the length of the border, connecting a row of villages. One of them is the village that Dani fled as a young man in 1982, when the Israeli Army swept across the border.

Dani and I watched the Israeli soldiers on the other side; one of them, shirtless, was climbing a ladder to fix a break in the fence. On our side, a group of U.N. peacekeepers from Fiji posed for pictures. A scrawl of graffiti paid tribute to Benjamin Netanyahu, the Israeli Prime Minister: “Bibi We Love You.”

“My father used to cross right here,” Dani said.

I asked Dani if Hezbollah’s dream of pushing Israel into the sea wasn’t dead, or waning fast. He shook his head. Hezbollah, I reminded him, was now governing Lebanon. It was evolving into something other than an armed group dedicated to destroying Israel. The Assad regime was collapsing, along with Hezbollah’s supply lines. Perhaps, I suggested, Hezbollah’s moment had passed. Dani’s eyes stayed fixed on Israel. “Next time, we’re going across,” he said. ♦