A former C.I.A. officer calls Suleimani, the head of Iran’s Quds Force, the “most powerful operative in the Middle East today.” Illustration by Krzysztof Domaradzki.

Last February, some of Iran’s most influential leaders gathered at the Amir al-Momenin Mosque, in northeast Tehran, inside a gated community reserved for officers of the Revolutionary Guard. They had come to pay their last respects to a fallen comrade. Hassan Shateri, a veteran of Iran’s covert wars throughout the Middle East and South Asia, was a senior commander in a powerful, élite branch of the Revolutionary Guard called the Quds Force. The force is the sharp instrument of Iranian foreign policy, roughly analogous to a combined C.I.A. and Special Forces; its name comes from the Persian word for Jerusalem, which its fighters have promised to liberate. Since 1979, its goal has been to subvert Iran’s enemies and extend the country’s influence across the Middle East. Shateri had spent much of his career abroad, first in Afghanistan and then in Iraq, where the Quds Force helped Shiite militias kill American soldiers.

Shateri had been killed two days before, on the road that runs between Damascus and Beirut. He had gone to Syria, along with thousands of other members of the Quds Force, to rescue the country’s besieged President, Bashar al-Assad, a crucial ally of Iran. In the past few years, Shateri had worked under an alias as the Quds Force’s chief in Lebanon; there he had helped sustain the armed group Hezbollah, which at the time of the funeral had begun to pour men into Syria to fight for the regime. The circumstances of his death were unclear: one Iranian official said that Shateri had been “directly targeted” by “the Zionist regime,” as Iranians habitually refer to Israel.

At the funeral, the mourners sobbed, and some beat their chests in the Shiite way. Shateri’s casket was wrapped in an Iranian flag, and gathered around it were the commander of the Revolutionary Guard, dressed in green fatigues; a member of the plot to murder four exiled opposition leaders in a Berlin restaurant in 1992; and the father of Imad Mughniyeh, the Hezbollah commander believed to be responsible for the bombings that killed more than two hundred and fifty Americans in Beirut in 1983. Mughniyeh was assassinated in 2008, purportedly by Israeli agents. In the ethos of the Iranian revolution, to die was to serve. Before Shateri’s funeral, Ayatollah Ali Khamenei, the country’s Supreme Leader, released a note of praise: “In the end, he drank the sweet syrup of martyrdom.”

Kneeling in the second row on the mosque’s carpeted floor was Major General Qassem Suleimani, the Quds Force’s leader: a small man of fifty-six, with silver hair, a close-cropped beard, and a look of intense self-containment. It was Suleimani who had sent Shateri, an old and trusted friend, to his death. As Revolutionary Guard commanders, he and Shateri belonged to a small fraternity formed during the Sacred Defense, the name given to the Iran-Iraq War, which lasted from 1980 to 1988 and left as many as a million people dead. It was a catastrophic fight, but for Iran it was the beginning of a three-decade project to build a Shiite sphere of influence, stretching across Iraq and Syria to the Mediterranean. Along with its allies in Syria and Lebanon, Iran forms an Axis of Resistance, arrayed against the region’s dominant Sunni powers and the West. In Syria, the project hung in the balance, and Suleimani was mounting a desperate fight, even if the price of victory was a sectarian conflict that engulfed the region for years.

Suleimani took command of the Quds Force fifteen years ago, and in that time he has sought to reshape the Middle East in Iran’s favor, working as a power broker and as a military force: assassinating rivals, arming allies, and, for most of a decade, directing a network of militant groups that killed hundreds of Americans in Iraq. The U.S. Department of the Treasury has sanctioned Suleimani for his role in supporting the Assad regime, and for abetting terrorism. And yet he has remained mostly invisible to the outside world, even as he runs agents and directs operations. “Suleimani is the single most powerful operative in the Middle East today,” John Maguire, a former C.I.A. officer in Iraq, told me, “and no one’s ever heard of him.”

When Suleimani appears in public—often to speak at veterans’ events or to meet with Khamenei—he carries himself inconspicuously and rarely raises his voice, exhibiting a trait that Arabs call khilib, or understated charisma. “He is so short, but he has this presence,” a former senior Iraqi official told me. “There will be ten people in a room, and when Suleimani walks in he doesn’t come and sit with you. He sits over there on the other side of room, by himself, in a very quiet way. Doesn’t speak, doesn’t comment, just sits and listens. And so of course everyone is thinking only about him.”

At the funeral, Suleimani was dressed in a black jacket and a black shirt with no tie, in the Iranian style; his long, angular face and his arched eyebrows were twisted with pain. The Quds Force had never lost such a high-ranking officer abroad. The day before the funeral, Suleimani had travelled to Shateri’s home to offer condolences to his family. He has a fierce attachment to martyred soldiers, and often visits their families; in a recent interview with Iranian media, he said, “When I see the children of the martyrs, I want to smell their scent, and I lose myself.” As the funeral continued, he and the other mourners bent forward to pray, pressing their foreheads to the carpet. “One of the rarest people, who brought the revolution and the whole world to you, is gone,” Alireza Panahian, the imam, told the mourners. Suleimani cradled his head in his palm and began to weep.

The early months of 2013, around the time of Shateri’s death, marked a low point for the Iranian intervention in Syria. Assad was steadily losing ground to the rebels, who are dominated by Sunnis, Iran’s rivals. If Assad fell, the Iranian regime would lose its link to Hezbollah, its forward base against Israel. In a speech, one Iranian cleric said, “If we lose Syria, we cannot keep Tehran.”

Although the Iranians were severely strained by American sanctions, imposed to stop the regime from developing a nuclear weapon, they were unstinting in their efforts to save Assad. Among other things, they extended a seven-billion-dollar loan to shore up the Syrian economy. “I don’t think the Iranians are calculating this in terms of dollars,” a Middle Eastern security official told me. “They regard the loss of Assad as an existential threat.” For Suleimani, saving Assad seemed a matter of pride, especially if it meant distinguishing himself from the Americans. “Suleimani told us the Iranians would do whatever was necessary,” a former Iraqi leader told me. “He said, ‘We’re not like the Americans. We don’t abandon our friends.’ ”

Last year, Suleimani asked Kurdish leaders in Iraq to allow him to open a supply route across northern Iraq and into Syria. For years, he had bullied and bribed the Kurds into coöperating with his plans, but this time they rebuffed him. Worse, Assad’s soldiers wouldn’t fight—or, when they did, they mostly butchered civilians, driving the populace to the rebels. “The Syrian Army is useless!” Suleimani told an Iraqi politician. He longed for the Basij, the Iranian militia whose fighters crushed the popular uprisings against the regime in 2009. “Give me one brigade of the Basij, and I could conquer the whole country,” he said. In August, 2012, anti-Assad rebels captured forty-eight Iranians inside Syria. Iranian leaders protested that they were pilgrims, come to pray at a holy Shiite shrine, but the rebels, as well as Western intelligence agencies, said that they were members of the Quds Force. In any case, they were valuable enough so that Assad agreed to release more than two thousand captured rebels to have them freed. And then Shateri was killed.

Finally, Suleimani began flying into Damascus frequently so that he could assume personal control of the Iranian intervention. “He’s running the war himself,” an American defense official told me. In Damascus, he is said to work out of a heavily fortified command post in a nondescript building, where he has installed a multinational array of officers: the heads of the Syrian military, a Hezbollah commander, and a coördinator of Iraqi Shiite militias, which Suleimani mobilized and brought to the fight. If Suleimani couldn’t have the Basij, he settled for the next best thing: Brigadier General Hossein Hamedani, the Basij’s former deputy commander. Hamedani, another comrade from the Iran-Iraq War, was experienced in running the kind of irregular militias that the Iranians were assembling, in order to keep on fighting if Assad fell.

Late last year, Western officials began to notice a sharp increase in Iranian supply flights into the Damascus airport. Instead of a handful a week, planes were coming every day, carrying weapons and ammunition—“tons of it,” the Middle Eastern security official told me—along with officers from the Quds Force. According to American officials, the officers coördinated attacks, trained militias, and set up an elaborate system to monitor rebel communications. They also forced the various branches of Assad’s security services—designed to spy on one another—to work together. The Middle Eastern security official said that the number of Quds Force operatives, along with the Iraqi Shiite militiamen they brought with them, reached into the thousands. “They’re spread out across the entire country,” he told me.

A turning point came in April, after rebels captured the Syrian town of Qusayr, near the Lebanese border. To retake the town, Suleimani called on Hassan Nasrallah, Hezbollah’s leader, to send in more than two thousand fighters. It wasn’t a difficult sell. Qusayr sits at the entrance to the Bekaa Valley, the main conduit for missiles and other matériel to Hezbollah; if it was closed, Hezbollah would find it difficult to survive. Suleimani and Nasrallah are old friends, having coöperated for years in Lebanon and in the many places around the world where Hezbollah operatives have performed terrorist missions at the Iranians’ behest. According to Will Fulton, an Iran expert at the American Enterprise Institute, Hezbollah fighters encircled Qusayr, cutting off the roads, then moved in. Dozens of them were killed, as were at least eight Iranian officers. On June 5th, the town fell. “The whole operation was orchestrated by Suleimani,” Maguire, who is still active in the region, said. “It was a great victory for him.”

Despite all of Suleimani’s rough work, his image among Iran’s faithful is that of an irreproachable war hero—a decorated veteran of the Iran-Iraq War, in which he became a division commander while still in his twenties. In public, he is almost theatrically modest. During a recent appearance, he described himself as “the smallest soldier,” and, according to the Iranian press, rebuffed members of the audience who tried to kiss his hand. His power comes mostly from his close relationship with Khamenei, who provides the guiding vision for Iranian society. The Supreme Leader, who usually reserves his highest praise for fallen soldiers, has referred to Suleimani as “a living martyr of the revolution.” Suleimani is a hard-line supporter of Iran’s authoritarian system. In July, 1999, at the height of student protests, he signed, with other Revolutionary Guard commanders, a letter warning the reformist President Mohammad Khatami that if he didn’t put down the revolt the military would—perhaps deposing Khatami in the process. “Our patience has run out,” the generals wrote. The police crushed the demonstrators, as they did again, a decade later.

Iran’s government is intensely fractious, and there are many figures around Khamenei who help shape foreign policy, including Revolutionary Guard commanders, senior clerics, and Foreign Ministry officials. But Suleimani has been given a remarkably free hand in implementing Khamenei’s vision. “He has ties to every corner of the system,” Meir Dagan, the former head of Mossad, told me. “He is what I call politically clever. He has a relationship with everyone.” Officials describe him as a believer in Islam and in the revolution; while many senior figures in the Revolutionary Guard have grown wealthy through the Guard’s control over key Iranian industries, Suleimani has been endowed with a personal fortune by the Supreme Leader. “He’s well taken care of,” Maguire said.

Suleimani lives in Tehran, and appears to lead the home life of a bureaucrat in middle age. “He gets up at four every morning, and he’s in bed by nine-thirty every night,” the Iraqi politician, who has known him for many years, told me, shaking his head in disbelief. Suleimani has a bad prostate and recurring back pain. He’s “respectful of his wife,” the Middle Eastern security official told me, sometimes taking her along on trips. He has three sons and two daughters, and is evidently a strict but loving father. He is said to be especially worried about his daughter Nargis, who lives in Malaysia. “She is deviating from the ways of Islam,” the Middle Eastern official said.

Maguire told me, “Suleimani is a far more polished guy than most. He can move in political circles, but he’s also got the substance to be intimidating.” Although he is widely read, his aesthetic tastes appear to be strictly traditional. “I don’t think he’d listen to classical music,” the Middle Eastern official told me. “The European thing—I don’t think that’s his vibe, basically.” Suleimani has little formal education, but, the former senior Iraqi official told me, “he is a very shrewd, frighteningly intelligent strategist.” His tools include payoffs for politicians across the Middle East, intimidation when it is needed, and murder as a last resort. Over the years, the Quds Force has built an international network of assets, some of them drawn from the Iranian diaspora, who can be called on to support missions. “They’re everywhere,” a second Middle Eastern security official said. In 2010, according to Western officials, the Quds Force and Hezbollah launched a new campaign against American and Israeli targets—in apparent retaliation for the covert effort to slow down the Iranian nuclear program, which has included cyber attacks and assassinations of Iranian nuclear scientists.

Since then, Suleimani has orchestrated attacks in places as far flung as Thailand, New Delhi, Lagos, and Nairobi—at least thirty attempts in the past two years alone. The most notorious was a scheme, in 2011, to hire a Mexican drug cartel to blow up the Saudi Ambassador to the United States as he sat down to eat at a restaurant a few miles from the White House. The cartel member approached by Suleimani’s agent turned out to be an informant for the U.S. Drug Enforcement Administration. (The Quds Force appears to be more effective close to home, and a number of the remote plans have gone awry.) Still, after the plot collapsed, two former American officials told a congressional committee that Suleimani should be assassinated. “Suleimani travels a lot,” one said. “He is all over the place. Go get him. Either try to capture him or kill him.” In Iran, more than two hundred dignitaries signed an outraged letter in his defense; a social-media campaign proclaimed, “We are all Qassem Suleimani.”

Several Middle Eastern officials, some of whom I have known for a decade, stopped talking the moment I brought up Suleimani. “We don’t want to have any part of this,” a Kurdish official in Iraq said. Among spies in the West, he appears to exist in a special category, an enemy both hated and admired: a Middle Eastern equivalent of Karla, the elusive Soviet master spy in John le Carré’s novels. When I called Dagan, the former Mossad chief, and mentioned Suleimani’s name, there was a long pause on the line. “Ah,” he said, in a tone of weary irony, “a very good friend.”

In March, 2009, on the eve of the Iranian New Year, Suleimani led a group of Iran-Iraq War veterans to the Paa-Alam Heights, a barren, rocky promontory on the Iraqi border. In 1986, Paa-Alam was the scene of one of the terrible battles over the Faw Peninsula, where tens of thousands of men died while hardly advancing a step. A video recording from the visit shows Suleimani standing on a mountaintop, recounting the battle to his old comrades. In a gentle voice, he speaks over a soundtrack of music and prayers.

“This is the Dasht-e-Abbas Road,” Suleimani says, pointing into the valley below. “This area stood between us and the enemy.” Later, Suleimani and the group stand on the banks of a creek, where he reads aloud the names of fallen Iranian soldiers, his voice trembling with emotion. During a break, he speaks with an interviewer, and describes the fighting in near-mystical terms. “The battlefield is mankind’s lost paradise—the paradise in which morality and human conduct are at their highest,” he says. “One type of paradise that men imagine is about streams, beautiful maidens, and lush landscape. But there is another kind of paradise—the battlefield.”

Suleimani was born in Rabor, an impoverished mountain village in eastern Iran. When he was a boy, his father, like many other farmers, took out an agricultural loan from the government of the Shah. He owed nine hundred toman—about a hundred dollars at the time—and couldn’t pay it back. In a brief memoir, Suleimani wrote of leaving home with a young relative named Ahmad Suleimani, who was in a similar situation. “At night, we couldn’t fall asleep with the sadness of thinking that government agents were coming to arrest our fathers,” he wrote. Together, they travelled to Kerman, the nearest city, to try to clear their family’s debt. The place was unwelcoming. “We were only thirteen, and our bodies were so tiny, wherever we went, they wouldn’t hire us,” he wrote. “Until one day, when we were hired as laborers at a school construction site on Khajoo Street, which was where the city ended. They paid us two toman per day.” After eight months, they had saved enough money to bring home, but the winter snow was too deep. They were told to seek out a local driver named Pahlavan—“Champion”—who was a “strong man who could lift up a cow or a donkey with his teeth.” During the drive, whenever the car got stuck, “he would lift up the Jeep and put it aside!” In Suleimani’s telling, Pahlavan is an ardent detractor of the Shah. He says of the two boys, “This is the time for them to rest and play, not work as a laborer in a strange city. I spit on the life they have made for us!” They arrived home, Suleimani writes, “just as the lights were coming on in the village homes. When the news travelled in our village, there was pandemonium.”

As a young man, Suleimani gave few signs of greater ambition. According to Ali Alfoneh, an Iran expert at the Foundation for Defense of Democracies, he had only a high-school education, and worked for Kerman’s municipal water department. But it was a revolutionary time, and the country’s gathering unrest was making itself felt. Away from work, Suleimani spent hours lifting weights in local gyms, which, like many in the Middle East, offered physical training and inspiration for the warrior spirit. During Ramadan, he attended sermons by a travelling preacher named Hojjat Kamyab—a protégé of Khamenei’s—and it was there that he became inspired by the possibility of Islamic revolution.

In 1979, when Suleimani was twenty-two, the Shah fell to a popular uprising led by Ayatollah Ruhollah Khomeini in the name of Islam. Swept up in the fervor, Suleimani joined the Revolutionary Guard, a force established by Iran’s new clerical leadership to prevent the military from mounting a coup. Though he received little training—perhaps only a forty-five-day course—he advanced rapidly. As a young guardsman, Suleimani was dispatched to northwestern Iran, where he helped crush an uprising by ethnic Kurds.

When the revolution was eighteen months old, Saddam Hussein sent the Iraqi Army sweeping across the border, hoping to take advantage of the internal chaos. Instead, the invasion solidified Khomeini’s leadership and unified the country in resistance, starting a brutal, entrenched war. Suleimani was sent to the front with a simple task, to supply water to the soldiers there, and he never left. “I entered the war on a fifteen-day mission, and ended up staying until the end,” he has said. A photograph from that time shows the young Suleimani dressed in green fatigues, with no insignia of rank, his black eyes focussed on a far horizon. “We were all young and wanted to serve the revolution,” he told an interviewer in 2005.

Suleimani earned a reputation for bravery and élan, especially as a result of reconnaissance missions he undertook behind Iraqi lines. He returned from several missions bearing a goat, which his soldiers slaughtered and grilled. “Even the Iraqis, our enemy, admired him for this,” a former Revolutionary Guard officer who defected to the United States told me. On Iraqi radio, Suleimani became known as “the goat thief.” In recognition of his effectiveness, Alfoneh said, he was put in charge of a brigade from Kerman, with men from the gyms where he lifted weights.

The Iranian Army was badly overmatched, and its commanders resorted to crude and costly tactics. In “human wave” assaults, they sent thousands of young men directly into the Iraqi lines, often to clear minefields, and soldiers died at a precipitous rate. Suleimani seemed distressed by the loss of life. Before sending his men into battle, he would embrace each one and bid him goodbye; in speeches, he praised martyred soldiers and begged their forgiveness for not being martyred himself. When Suleimani’s superiors announced plans to attack the Faw Peninsula, he dismissed them as wasteful and foolhardy. The former Revolutionary Guard officer recalled seeing Suleimani in 1985, after a battle in which his brigade had suffered many dead and wounded. He was sitting alone in a corner of a tent. “He was very silent, thinking about the people he’d lost,” the officer said.

Ahmad, the young relative who travelled with Suleimani to Kerman, was killed in 1984. On at least one occasion, Suleimani himself was wounded. Still, he didn’t lose enthusiasm for his work. In the nineteen-eighties, Reuel Marc Gerecht was a young C.I.A. officer posted to Istanbul, where he recruited from the thousands of Iranian soldiers who went there to recuperate. “You’d get a whole variety of guardsmen,” Gerecht, who has written extensively on Iran, told me. “You’d get clerics, you’d get people who came to breathe and whore and drink.” Gerecht divided the veterans into two groups. “There were the broken and the burned out, the hollow-eyed—the guys who had been destroyed,” he said. “And then there were the bright-eyed guys who just couldn’t wait to get back to the front. I’d put Suleimani in the latter category.”

Ryan Crocker, the American Ambassador to Iraq from 2007 to 2009, got a similar feeling. During the Iraq War, Crocker sometimes dealt with Suleimani indirectly, through Iraqi leaders who shuttled in and out of Tehran. Once, he asked one of the Iraqis if Suleimani was especially religious. The answer was “Not really,” Crocker told me. “He attends mosque periodically. Religion doesn’t drive him. Nationalism drives him, and the love of the fight.”

Iran’s leaders took two lessons from the Iran-Iraq War. The first was that Iran was surrounded by enemies, near and far. To the regime, the invasion was not so much an Iraqi plot as a Western one. American officials were aware of Saddam’s preparations to invade Iran in 1980, and they later provided him with targeting information used in chemical-weapons attacks; the weapons themselves were built with the help of Western European firms. The memory of these attacks is an especially bitter one. “Do you know how many people are still suffering from the effects of chemical weapons?” Mehdi Khalaji, a fellow at the Washington Institute for Near East Policy, said. “Thousands of former soldiers. They believe these were Western weapons given to Saddam.” In 1987, during a battle with the Iraqi Army, a division under Suleimani’s command was attacked by artillery shells containing chemical weapons. More than a hundred of his men suffered the effects.

The other lesson drawn from the Iran-Iraq War was the futility of fighting a head-to-head confrontation. In 1982, after the Iranians expelled the Iraqi forces, Khomeini ordered his men to keep going, to “liberate” Iraq and push on to Jerusalem. Six years and hundreds of thousands of lives later, he agreed to a ceasefire. According to Alfoneh, many of the generals of Suleimani’s generation believe they could have succeeded had the clerics not flinched. “Many of them feel like they were stabbed in the back,” he said. “They have nurtured this myth for nearly thirty years.” But Iran’s leaders did not want another bloodbath. Instead, they had to build the capacity to wage asymmetrical warfare—attacking stronger powers indirectly, outside of Iran.

The Quds Force was an ideal tool. Khomeini had created the prototype for the force in 1979, with the goal of protecting Iran and exporting the Islamic Revolution. The first big opportunity came in Lebanon, where Revolutionary Guard officers were dispatched in 1982 to help organize Shiite militias in the many-sided Lebanese civil war. Those efforts resulted in the creation of Hezbollah, which developed under Iranian guidance. Hezbollah’s military commander, the brilliant and murderous Imad Mughniyeh, helped form what became known as the Special Security Apparatus, a wing of Hezbollah that works closely with the Quds Force. With assistance from Iran, Hezbollah helped orchestrate attacks on the American Embassy and on French and American military barracks. “In the early days, when Hezbollah was totally dependent on Iranian help, Mughniyeh and others were basically willing Iranian assets,” David Crist, a historian for the U.S. military and the author of “The Twilight War,” says.

For all of the Iranian regime’s aggressiveness, some of its religious zeal seemed to burn out. In 1989, Khomeini stopped urging Iranians to spread the revolution, and called instead for expediency to preserve its gains. Persian self-interest was the order of the day, even if it was indistinguishable from revolutionary fervor. In those years, Suleimani worked along Iran’s eastern frontier, aiding Afghan rebels who were holding out against the Taliban. The Iranian regime regarded the Taliban with intense hostility, in large part because of their persecution of Afghanistan’s minority Shiite population. (At one point, the two countries nearly went to war; Iran mobilized a quarter of a million troops, and its leaders denounced the Taliban as an affront to Islam.) In an area that breeds corruption, Suleimani made a name for himself battling opium smugglers along the Afghan border.

In 1998, Suleimani was named the head of the Quds Force, taking over an agency that had already built a lethal résumé: American and Argentine officials believe that the Iranian regime helped Hezbollah orchestrate the bombing of the Israeli Embassy in Buenos Aires in 1992, which killed twenty-nine people, and the attack on the Jewish center in the same city two years later, which killed eighty-five. Suleimani has built the Quds Force into an organization with extraordinary reach, with branches focussed on intelligence, finance, politics, sabotage, and special operations. With a base in the former U.S. Embassy compound in Tehran, the force has between ten thousand and twenty thousand members, divided between combatants and those who train and oversee foreign assets. Its members are picked for their skill and their allegiance to the doctrine of the Islamic Revolution (as well as, in some cases, their family connections). According to the Israeli newspaper Israel Hayom, fighters are recruited throughout the region, trained in Shiraz and Tehran, indoctrinated at the Jerusalem Operation College, in Qom, and then “sent on months-long missions to Afghanistan and Iraq to gain experience in field operational work. They usually travel under the guise of Iranian construction workers.”

After taking command, Suleimani strengthened relationships in Lebanon, with Mughniyeh and with Hassan Nasrallah, Hezbollah’s chief. By then, the Israeli military had occupied southern Lebanon for sixteen years, and Hezbollah was eager to take control of the country, so Suleimani sent in Quds Force operatives to help. “They had a huge presence—training, advising, planning,” Crocker said. In 2000, the Israelis withdrew, exhausted by relentless Hezbollah attacks. It was a signal victory for the Shiites, and, Crocker said, “another example of how countries like Syria and Iran can play a long game, knowing that we can’t.”

Since then, the regime has given aid to a variety of militant Islamist groups opposed to America’s allies in the region, such as Saudi Arabia and Bahrain. The help has gone not only to Shiites but also to Sunni groups like Hamas—helping to form an archipelago of alliances that stretches from Baghdad to Beirut. “No one in Tehran started out with a master plan to build the Axis of Resistance, but opportunities presented themselves,” a Western diplomat in Baghdad told me. “In each case, Suleimani was smarter, faster, and better resourced than anyone else in the region. By grasping at opportunities as they came, he built the thing, slowly but surely.”

In the chaotic days after the attacks of September 11th, Ryan Crocker, then a senior State Department official, flew discreetly to Geneva to meet a group of Iranian diplomats. “I’d fly out on a Friday and then back on Sunday, so nobody in the office knew where I’d been,” Crocker told me. “We’d stay up all night in those meetings.” It seemed clear to Crocker that the Iranians were answering to Suleimani, whom they referred to as “Haji Qassem,” and that they were eager to help the United States destroy their mutual enemy, the Taliban. Although the United States and Iran broke off diplomatic relations in 1980, after American diplomats in Tehran were taken hostage, Crocker wasn’t surprised to find that Suleimani was flexible. “You don’t live through eight years of brutal war without being pretty pragmatic,” he said. Sometimes Suleimani passed messages to Crocker, but he avoided putting anything in writing. “Haji Qassem’s way too smart for that,” Crocker said. “He’s not going to leave paper trails for the Americans.”

Before the bombing began, Crocker sensed that the Iranians were growing impatient with the Bush Administration, thinking that it was taking too long to attack the Taliban. At a meeting in early October, 2001, the lead Iranian negotiator stood up and slammed a sheaf of papers on the table. “If you guys don’t stop building these fairy-tale governments in the sky, and actually start doing some shooting on the ground, none of this is ever going to happen!” he shouted. “When you’re ready to talk about serious fighting, you know where to find me.” He stomped out of the room. “It was a great moment,” Crocker said.

The coöperation between the two countries lasted through the initial phase of the war. At one point, the lead negotiator handed Crocker a map detailing the disposition of Taliban forces. “Here’s our advice: hit them here first, and then hit them over here. And here’s the logic.” Stunned, Crocker asked, “Can I take notes?” The negotiator replied, “You can keep the map.” The flow of information went both ways. On one occasion, Crocker said, he gave his counterparts the location of an Al Qaeda facilitator living in the eastern city of Mashhad. The Iranians detained him and brought him to Afghanistan’s new leaders, who, Crocker believes, turned him over to the U.S. The negotiator told Crocker, “Haji Qassem is very pleased with our coöperation.”

The good will didn’t last. In January, 2002, Crocker, who was by then the deputy chief of the American Embassy in Kabul, was awakened one night by aides, who told him that President George W. Bush, in his State of the Union Address, had named Iran as part of an “Axis of Evil.” Like many senior diplomats, Crocker was caught off guard. He saw the negotiator the next day at the U.N. compound in Kabul, and he was furious. “You completely damaged me,” Crocker recalled him saying. “Suleimani is in a tearing rage. He feels compromised.” The negotiator told Crocker that, at great political risk, Suleimani had been contemplating a complete reëvaluation of the United States, saying, “Maybe it’s time to rethink our relationship with the Americans.” The Axis of Evil speech brought the meetings to an end. Reformers inside the government, who had advocated a rapprochement with the United States, were put on the defensive. Recalling that time, Crocker shook his head. “We were just that close,” he said. “One word in one speech changed history.”

Before the meetings fell apart, Crocker talked with the lead negotiator about the possibility of war in Iraq. “Look,” Crocker said, “I don’t know what’s going to happen, but I do have some responsibility for Iraq—it’s my portfolio—and I can read the signs, and I think we’re going to go in.” He saw an enormous opportunity. The Iranians despised Saddam, and Crocker figured that they would be willing to work with the U.S. “I was not a fan of the invasion,” he told me. “But I was thinking, If we’re going to do it, let’s see if we can flip an enemy into a friend—at least tactically for this, and then let’s see where we can take it.” The negotiator indicated that the Iranians were willing to talk, and that Iraq, like Afghanistan, was part of Suleimani’s brief: “It’s one guy running both shows.”

After the invasion began, in March, 2003, Iranian officials were frantic to let the Americans know that they wanted peace. Many of them watched the regimes topple in Afghanistan and Iraq and were convinced that they were next. “They were scared shitless,” Maguire, the former C.I.A. officer in Baghdad, told me. “They were sending runners across the border to our élite elements saying, ‘Look, we don’t want any trouble with you.’ We had an enormous upper hand.” That same year, American officials determined that Iran had reconfigured its plans to develop a nuclear weapon to proceed more slowly and covertly, lest it invite a Western attack.

After Saddam’s regime collapsed, Crocker was dispatched to Baghdad to organize a fledgling government, called the Iraqi Governing Council. He realized that many Iraqi politicians were flying to Tehran for consultations, and he jumped at the chance to negotiate indirectly with Suleimani. In the course of the summer, Crocker passed him the names of prospective Shiite candidates, and the two men vetted each one. Crocker did not offer veto power, but he abandoned candidates whom Suleimani found especially objectionable. “The formation of the governing council was in its essence a negotiation between Tehran and Washington,” he said.

That exchange was the high point of Iranian-American coöperation. “After we formed the governing council, everything collapsed,” Crocker said. As the American occupation faltered, Suleimani began an aggressive campaign of sabotage. Many Americans and Iraqis I interviewed thought that the change of strategy was the result of opportunism: the Iranians became aggressive when the fear of an American invasion began to recede.

For years, Suleimani had sent operatives into Iraq to cultivate Shiite militias, so, when Saddam fell, he already had a fighting force in place: the Badr Brigade, the armed wing of a Shiite political party called the Supreme Council for the Islamic Revolution in Iraq. The Party’s leaders so thoroughly identified with the Iranian revolution that Badr’s militiamen had fought alongside Iranian forces in the Iran-Iraq War.

The Badr Brigade spent much of its time carrying out revenge killings against Baathists, and largely held its fire against the Americans. But another Iranian-backed militia—the Mahdi Army, headed by the populist cleric Moqtada al-Sadr—began confronting the Americans early. In August, 2004, after the Americans launched a particularly bloody counteroffensive, I walked through a makeshift graveyard in the holy city of Najaf, south of Baghdad, and found dozens of shallow graves, each marked by a tiny glass jar containing a slip of paper with the fallen fighter’s name and address. Many of them were marked “Tehran.”

Suleimani found Sadr unpredictable and difficult to manage, so the Quds Force began to organize other militias that were willing to attack the Americans. Its operatives trained fighters in Iran, sometimes helped by their comrades in Hezbollah. Suleimani’s control over some of the Iraqi militias at times appeared to be total. At one point, a senior Iraqi official, on a trip to Washington, publicly blamed the Supreme Leader for escalating the violence in Iraq. Soon after returning to Baghdad, he told me, he received messages from the leaders of two Iraqi Shiite militias. Both posed the same question: Do you want to die?

In 2004, the Quds Force began flooding Iraq with lethal roadside bombs that the Americans referred to as E.F.P.s, for “explosively formed projectiles.” The E.F.P.s, which fire a molten copper slug able to penetrate armor, began to wreak havoc on American troops, accounting for nearly twenty per cent of combat deaths. E.F.P.s could be made only by skilled technicians, and they were often triggered by sophisticated motion sensors. “There was zero question where they were coming from,” General Stanley McChrystal, who at the time was the head of the Joint Special Operations Command, told me. “We knew where all the factories were in Iran. The E.F.P.s killed hundreds of Americans.”

Suleimani’s campaign against the United States crossed the Sunni-Shiite divide, which he has always been willing to set aside for a larger purpose. Iraqi and Western officials told me that, early in the war, Suleimani encouraged the head of intelligence for the Assad regime to facilitate the movement of Sunni extremists through Syria to fight the Americans. In many cases, Al Qaeda was also allowed a degree of freedom in Iran as well. Crocker told me that in May, 2003, the Americans received intelligence that Al Qaeda fighters in Iran were preparing an attack on Western targets in Saudi Arabia. Crocker was alarmed. “They were there, under Iranian protection, planning operations,” he said. He flew to Geneva and passed a warning to the Iranians, but to no avail; militants bombed three residential compounds in Riyadh, killing thirty-five people, including nine Americans.

As it turned out, the Iranian strategy of abetting Sunni extremists backfired horrendously: shortly after the occupation began, the same extremists began attacking Shiite civilians and the Shiite-dominated Iraqi government. It was a preview of the civil war to come. “Welcome to the Middle East,” the Western diplomat in Baghdad told me. “Suleimani wanted to bleed the Americans, so he invited in the jihadis, and things got out of control.”

Still, Iran’s policy toward the Americans in Iraq was not entirely hostile—both countries, after all, were trying to empower Iraq’s Shiite majority—and so Suleimani alternated between bargaining with the Americans and killing them. Throughout the war, he summoned Iraqi leaders to Tehran to broker deals, usually intended to maximize Shiite power. At least once, he even travelled into the heart of American power in Baghdad. “Suleimani came into the Green Zone to meet the Iraqis,” the Iraqi politician told me. “I think the Americans wanted to arrest him, but they figured they couldn’t.”

As both sides sought an advantage, the shifting allegiances led to uncomfortable, sometimes bizarre encounters. The leaders of the two main Kurdish parties, Massoud Barzani and Jalal Talabani, met regularly with both Suleimani and the Americans. While the Kurds’ relationship with the U.S. was usually warm, their ties to Iranian leaders like Suleimani were deeper and more complex; the Iranian regime had sheltered Iraq’s Kurds during their war with Saddam. But it was never an equal relationship. Kurdish leaders say that Suleimani’s objective has always been to keep Iraq’s political parties divided and unstable, insuring that the country stayed weak: the Iran-Iraq War was never far from his mind. “It is very difficult for us to say no to Suleimani,” a senior Kurdish official told me. “When we say no, he makes trouble for us. Bombings. Shootings. The Iranians are our neighbors. They’ve always been there, and they always will be. We have to deal with them.”

A senior intelligence officer in Baghdad recalled visiting Talabani at his house during a trip to northern Iraq. When he walked in, Qassem Suleimani was sitting there, wearing a black shirt and black jacket. The two men looked each other up and down. “He knew who I was; I knew who he was. We shook hands, didn’t say anything,” the officer said. “I’ve never seen Talabani so deferential to anyone. He was terrified.”

In the years after the invasion, General McChrystal concentrated on defeating Sunni insurgents, and, like other American commanders in Iraq, he largely refrained from pursuing Quds Force agents. Provoking Iran would only exacerbate the conflict, and, in any case, many of the agents operated under the protection of diplomatic cover. But, as the war dragged on, the Iranian-backed militias loomed ever larger. In late 2006, McChrystal told me, he formed a task force to kill and capture Iranian-backed insurgents, as well as Quds Force operatives.

That December, American commandos raided the compound of Abdul Aziz al-Hakim, a powerful Shiite politician, and found General Mohsen Chizari, the head of operations for the Quds Force. According to “The Endgame,” by Michael Gordon and Bernard Trainor, the commandos detained Chizari, sending shock waves through Baghdad. “Everybody was stunned,” a former senior military commander told me. “All the Iranians were stunned. We had broken the unwritten law.” Nuri al-Maliki, the Iraqi Prime Minister, demanded that the Americans turn over Chizari. When they did—reluctantly—Maliki released him. After the incident, the American Ambassador told Maliki that the next time they caught an Iranian operative they were going to keep him.

A month later, McChrystal received reports that General Mohammed Ali Jafari, the head of Iran’s Revolutionary Guard, might be in a convoy heading toward the Iraqi border. According to other intelligence sources, Suleimani was riding with him. A group of Kurdish fighters were waiting to welcome them when they crossed over. McChrystal decided to allow the Iranians to cross the border. “We didn’t want to get into a gunfight with the Kurds,” he said.

McChrystal’s men tracked the convoy as it drove a hundred miles into Iraq, to the Kurdish city of Erbil, and stopped at a nondescript building, which had a small sign that read “Consulate.” No one knew that such a consulate existed, but the fact that it did meant that the men inside were operating under diplomatic cover. The Americans moved in anyway, and took five Iranians into custody. All were carrying diplomatic passports, and all, according to McChrystal, were Quds Force members. Neither Suleimani nor Jafari was there; they had evidently broken off from the convoy at the last minute and taken refuge in a safe house controlled by the Kurdish leader Massoud Barzani. “Suleimani was lucky,” Dagan, the former Mossad chief, told me, referring to the raid. “It’s important to be lucky.”

Nine days later, five new black S.U.V.s pulled up to the gates of the Karbala Provincial Center, in southern Iraq. The men inside spoke English, wore American-style uniforms, and flashed I.D.s, and so they were allowed through the gates. In the compound, they jumped out of their vehicles and ran directly to a building where American soldiers were working. They killed one and captured four, ignoring everyone else. In a few hours, the four captives were dead, shot at close range.

The raid was carried out by Asa’ib Ahl al-Haq, one of the Iranian-backed militias. American officials speculated that Suleimani had ordered the raid, in response to the capture of the Quds Force operatives in Erbil. Within two months, the Americans had killed the alleged leader of the attack and rounded up several of the participants. One of them was Ali Musa Daqduq, a Hezbollah commander who had trained in Iran. At first, Daqduq pretended to be unable to speak, and the Americans nicknamed him Hamid the Mute. But after a time, they said, he started talking, and told them that the operation had been ordered by Iranian officials. For the first time, American commanders publicly pointed to Suleimani. At a press conference, Brigadier General Kevin Bergner said, “The Quds Force knew of and supported planning for the eventual Karbala attack that killed five coalition soldiers.”

As the covert war with Iran intensified, American officials considered crossing into Iran to attack training camps and bomb factories. “Some of us wanted very badly to hit them,” a senior American officer who was in Iraq at the time told me. Those debates lasted well into 2011, until the last American soldiers left the country. Each time, the Americans decided against crossing the border, figuring that it would be too easy for the Iranians to escalate the fighting.

Around the same time, Suleimani struck up a correspondence with senior American officials, sending messages through intermediaries—sometimes seeking to reassure the Americans, sometimes to extract something. One of the first came in early 2008, when the Iraqi President, Jalal Talabani, handed a cell phone with a text message to General David Petraeus, who had taken over the year before as the commander of American forces. “Dear General Petraeus,” the text read, “you should know that I, Qassem Suleimani, control the policy for Iran with respect to Iraq, Lebanon, Gaza and Afghanistan. And indeed, the ambassador in Baghdad is a Quds Force member. The individual who’s going to replace him is a Quds Force member.” After the five American soldiers were killed in Karbala, Suleimani sent a message to the American Ambassador. “I swear on the grave of Khomeini I haven’t authorized a bullet against the U.S.,” Suleimani said. None of the Americans believed him.

In a report to the White House, Petraeus wrote that Suleimani was “truly evil.” Yet at times the two men were all but negotiating. According to diplomatic cables revealed by WikiLeaks, Petraeus sent messages through Iraqi officials to Suleimani, asking him to call off rocket attacks on the American Embassy and on U.S. bases. In 2008, the Americans and the Iraqi Army were pressing an offensive against the Mahdi Army—Moqtada al-Sadr’s Shiite militia—and, in retribution, the militia was bombarding the Green Zone regularly. Suleimani, who sensed a political opening, sent Petraeus a message lamenting the situation and saying that he had assigned men to apprehend the attackers. Petraeus replied, “I was born on a Sunday, but it wasn’t last Sunday.” Eventually, Suleimani brokered a ceasefire between Sadr and the government.

At times, Suleimani seemed to take pleasure in taunting his American counterparts, and stories of his exploits spread. In the summer of 2006, during the thirty-four-day war between Israel and Hezbollah in Lebanon, the violence in Baghdad appeared to ebb. When the fighting ended, the Iraqi politician told me, Suleimani supposedly sent a message to the American command. “I hope you have been enjoying the peace and quiet in Baghdad,” it read. “I’ve been busy in Beirut!”

In a speech in 1990, Khamenei said that the mission of the Quds Force is to “establish popular Hezbollah cells all over the world.” Although that goal has not been met, Hezbollah has become the most influential force in Lebanon—a military power and a political party that nearly supersedes the state. Some experts on the region believe that it has grown less dependent on Iran as it has matured. But, at a dinner in Beirut last year, Walid Joumblatt, a Lebanese politician, complained that Hezbollah’s leaders were still in thrall to Tehran. “You have to sit and talk with them, but what do you say?” he said to me. “They don’t decide. It’s Khamenei and Qassem Suleimani who decide.”

Hezbollah’s leader, Hassan Nasrallah, has endorsed the concept of Velayat-e Faqih, which recognizes Iran’s Supreme Leader as the ultimate authority, and he has acknowledged the presence of Quds Force operatives in Lebanon. From 2000 to 2006, Iran contributed a hundred million dollars a year to Hezbollah. Its fighters are attractive proxies: unlike the Iranians, they speak Arabic, making them better equipped to operate in Syria and elsewhere in the Arab world. Working with the Iranians, they have either launched or prepared to launch attacks in Cyprus, Azerbaijan, and Turkey.

They don’t always act together. After a Hezbollah operative attacked a tour bus filled with Israelis in Bulgaria, last July, American authorities learned that Suleimani had asked his subordinates, “Does anyone know about this?” No one did. “Hezbollah acted on its own in that one,” an American defense official told me. Nonetheless, the Quds Force appears to have been involved in a number of the most significant moments in Lebanon’s recent history. In 2006, Nasrallah ordered a group of his fighters to kidnap Israeli soldiers—an operation that the Middle Eastern security official told me was carried out with Suleimani’s help. A brief but fierce war ensued, in which the Israel Defense Forces destroyed much of Lebanon. “I don’t think Suleimani expected that reaction,” the official said.

The question of Iranian influence in Lebanon resurfaced in 2011, when the United Nations-backed Special Tribunal for Lebanon charged four senior members of Hezbollah with assassinating the former Lebanese Prime Minister, Rafik Hariri, in 2005. Hariri, a Sunni, had been trying to take Lebanon out of the Iranian-Syrian orbit. On Valentine’s Day, he was killed by a suicide truck bomb whose payload weighed more than five thousand pounds.

Prosecutors identified the alleged Hezbollah assassins by means of “co-location analysis”—matching disposable cell phones used at the time of the murder with other phones that belonged to the suspects. They refrained from indicting Syrian officials, but, they said, they had convincing evidence that Assad’s government was involved in Hariri’s killing. A senior investigator for the Special Tribunal told me that there was also reason to suspect the Iranians: “Our theory of the case was that Hezbollah pulled the trigger, but could not and would not have done so without the blessing and logistical support from both Syria and Iran.” One of the phones believed to have been used by the killers had made at least a dozen calls to Iran before and after the assassination. But investigators told me that they didn’t know who in Iran was called, and that they couldn’t persuade Western intelligence agencies to help them. As it turned out, the agencies knew quite a bit. The senior intelligence officer told me that Iranian operatives were overheard talking minutes before the assassination. “There were Iranians on the phones directing the attack,” he said. Robert Baer, a former senior C.I.A. official, told me, “If indeed Iran was involved, Suleimani was undoubtedly at the center of this.”

Meanwhile, the four Hezbollah suspects in the killing have disappeared. One of them, Mustafa Badreddine—Imad Mughniyeh’s brother-in-law and a longtime Hezbollah bomb maker—was spotted in Syria by the rebels, who say that he is fighting for Assad.

On December 22, 2010, James Jeffrey, the American Ambassador to Iraq, and General Lloyd Austin, the top American commander there, issued a note of congratulations to the Iraqi people on the formation of a new government, led by Prime Minister Nuri al-Maliki. The country had been without a government for nine months, after parliamentary elections ended in an impasse. The composition of the government was critical; at the time of the election, there were still nearly a hundred thousand American troops in the country, and U.S. commanders were still hoping to leave a residual force behind. “We look forward to working with the new coalition government in furthering our common vision of a democratic Iraq,” the two men said.

What Jeffrey and Austin didn’t say was that the crucial deal that brought the Iraqi government together was made not by them but by Suleimani. In the months before, according to several Iraqi and Western officials, Suleimani invited senior Shiite and Kurdish leaders to meet with him in Tehran and Qom, and extracted from them a promise to support Maliki, his preferred candidate. The deal had a complex array of enticements. Maliki and Assad disliked each other; Suleimani brought them together by forging an agreement to build a lucrative oil pipeline from Iraq to the Syrian border. In order to bring the cleric Moqtada al-Sadr in line, Suleimani agreed to place his men in the Iraqi service ministries.

Most remarkable, according to the Iraqi and Western officials, were the two conditions that Suleimani imposed on the Iraqis. The first was that Jalal Talabani, a longtime friend of the Iranian regime, become President. The second was that Maliki and his coalition partners insist that all American troops leave the country. “Suleimani said: no Americans,” the former Iraqi leader told me. “A ten-year relationship, down the drain.”

Iraqi officials told me that, at the time of Jeffrey’s announcement, the Americans knew that Suleimani had pushed them out of the country but were too embarrassed to admit it in public. “We were laughing at the Americans,” the former Iraqi leader told me, growing angry as he recalled the situation. “Fuck it! Fuck it!” he said. “Suleimani completely outmaneuvered them, and in public they were congratulating themselves for putting the government together.”

The deal was a heavy blow to Ayad Allawi, a pro-American secular politician whose party had won the most parliamentary seats in the elections, but who failed to put together a majority coalition. In an interview in Jordan, he said that with U.S. backing he could have built a majority. Instead, the Americans pushed him aside in favor of Maliki. He told me that Vice-President Joe Biden called to tell him to abandon his bid for Prime Minister, saying, “You can’t form a government.”

Allawi said he suspected that the Americans weren’t willing to deal with the trouble the Iranians would have made if he had become Prime Minister. They wanted to stay in Iraq, he said, but only if the effort involved was minimal. “I needed American support,” he said. “But they wanted to leave, and they handed the country to the Iranians. Iraq is a failed state now, an Iranian colony.”

According to American and Iraqi former officials, Suleimani exerts leverage over Iraqi politics by paying officials, by subsidizing newspapers and television stations, and, when necessary, by intimidation. Few are immune to his enticements. “I have yet to see one Shia political party not taking money from Qassem Suleimani,” the former senior Iraqi official told me. “He’s the most powerful man in Iraq, without question.”

Even Maliki often feels like a prisoner of the Iranians. Exiled by Saddam, Maliki lived for a short time in Iran, but then moved to Syria—in part to escape Iranian influence, Iraqis who know him say. Crocker said that Maliki once told him, “You can’t know what arrogance is until you are an Iraqi Arab forced to take refuge with the Iranians.” The Iraqi politician, who is close to both men, told me that Maliki resents Suleimani, and that the feeling is mutual. “Maliki says Suleimani doesn’t listen,” he told me. “Suleimani says Maliki just lies.”

Still, Maliki may be amply repaying Suleimani for his efforts to make him Prime Minister. According to the former senior intelligence officer, Maliki’s government is presiding over a number of schemes, amounting to hundreds of millions of dollars a year, to help the Iranian regime outwit Western economic sanctions. A prominent Iraqi businessman told me that Iranian-backed agents regularly use the Iraqi banking system to undertake fraudulent transactions that allow them to sell Iraqi currency at a huge profit. “If the banks refuse, they are shut down by the government,” he said.

The other main source of revenue for the Iranians is oil, officials say: Maliki’s government sets aside the equivalent of two hundred thousand barrels of oil a day—about twenty million dollars’ worth, at current prices—and sends the money to Suleimani. In this way, the Quds Force has made itself immune to the economic pressures of Western sanctions. “It’s a self-funding covert-action program,” the former senior intelligence officer said. “Suleimani doesn’t even need the Iranian budget to fund his operations.”

Last December, when Assad’s regime appeared close to collapse, American officials spotted Syrian technicians preparing bombs carrying the nerve agent sarin to be loaded onto aircraft. All indications were that they were plotting an enormous chemical attack. Frantic, the Americans called leaders in Russia, who called their counterparts in Tehran. According to the American defense official, Suleimani appeared to be instrumental in persuading Assad to refrain from using the weapons.

Suleimani’s sentiments about the ethics of chemical weapons are unknown. During the Iran-Iraq War, thousands of Iranian soldiers suffered from chemical attacks, and the survivors still speak publicly of the trauma. But some American officials believe that his efforts to restrain Assad had a more pragmatic inspiration: the fear of provoking American military intervention. “Both the Russians and the Iranians have said to Assad, ‘We can’t support you in the court of world opinion if you use this stuff,’ ” a former senior American military official said.

The regime is believed to have used chemical weapons at least fourteen times since last year. Yet even after the enormous sarin attack on August 21st, which killed fourteen hundred civilians, Suleimani’s support for Syria has been unbending. To save Assad, Suleimani has called on every asset he built since taking over the Quds Force: Hezbollah fighters, Shiite militiamen from around the Arab world, and all the money and matériel he could squeeze out of his own besieged government. In Baghdad, a young Iraqi Shiite who called himself Abu Hassan told me that he was recruited to fight by a group of Iraqi men. He took a bus to the Iranian city of Mashhad, where he and three dozen other Iraqis received two weeks of instruction from Iranian trainers. The men travelled to the Shiite shrine of Sayyidah Zaynab, near Damascus, where they spent three months fighting for the Assad government, along with soldiers from Hezbollah and snipers from Iran. “We lost a lot of people,” Abu Hassan told me.

Suleimani’s greatest achievement may be persuading his proxies in the Iraqi government to allow Iran to use its airspace to fly men and munitions to Damascus. General James Mattis, who until March was the commander of all American military forces in the Middle East, told me that without this aid the Assad regime would have collapsed months ago. The flights are overseen by the Iraqi transportation minister, Hadi al-Amri, who is an old ally of Suleimani’s—the former head of the Badr Brigade, and a soldier on the Iranian side in the Iran-Iraq War. In an interview in Baghdad, Amri denied that the Iranians were using Iraqi airspace to send weapons. But he made clear his affection for his former commander. “I love Qassem Suleimani!” he said, pounding the table. “He is my dearest friend.”

So far, Maliki has resisted pressure to supply Assad overland through Iraq. But he hasn’t stopped the flights; the prospect of a radical Sunni regime in Syria overcame his reservations about becoming involved in a civil war. “Maliki dislikes the Iranians, and he loathes Assad, but he hates Al Nusra,” Crocker told me. “He doesn’t want an Al Qaeda government in Damascus.”

This kind of starkly sectarian atmosphere may be Suleimani’s most lasting impact on the Middle East. To save his Iranian empire in Syria and Lebanon, he has helped fuel a Sunni-Shiite conflict that threatens to engulf the region for years to come—a war that he appears happy to wage. “He has every reason to believe that Iran is the rising power in the region,” Mattis told me. “We’ve never dealt him a body blow.”

In June, a new, moderate President, Hassan Rouhani, was elected in Iran, promising to end the sanctions, which have exhausted the country and demolished its middle class. Hopes have risen in the West that Khamenei might allow Rouhani to strike a deal. Although Rouhani is a moderate only by Iranian standards—he is a Shiite cleric and a longtime adherent of the revolution—his new administration has made a series of good-will gestures, including the release of eleven political prisoners and an exchange of letters with President Obama. Rouhani is in New York this week to speak at the United Nations and, possibly, to meet with Obama. The talks will surely center on the potential for Iran to restrain its nuclear program, in exchange for relaxed sanctions.

Many in the West are hoping that Iran will also help find an end to the grinding war in Syria. Assad’s deputy prime minister recently offered the possibility of a cease-fire, saying, “Let nobody have any fear that the regime in its present form will continue.” But he did not say that Assad would step down, which the rebels have said is a necessary condition of negotiations. There have been hints from powerful Iranians that Assad isn’t worth holding on to. In a recent speech, the former President Hashemi Rafsanjani said, “The people have been the target of chemical attacks by their own government.” (After a leaked recording of the speech caused a stir in Iran, Rafsanjani denied the remarks.) But a less sympathetic regime in Syria would split the Axis of Resistance, and radically complicate Iran’s partnership with Hezbollah. In any case, the Iranian regime may be too fragmented to come to a consensus. “Anytime you see a statement coming out of the government, just remember there’s a rat’s nest of people fighting underneath the surface,” Kevan Harris, a sociologist at Princeton who has studied Iran extensively, told me. As Rouhani tries to engage the West, he will have to contend with the hard-liners, including Suleimani and his comrades, who for more than a decade have defined their foreign policy as a covert war on the U.S. and Israel. “They don’t trust the other side,” Harris said. “They feel that any concession they make will be seen by the West as a sign of weakness.”

For Suleimani, giving up Assad would mean abandoning the project of expansion that has occupied him for fifteen years. In a recent speech before the Assembly of Experts—the clerics who choose the Supreme Leader—he spoke about Syria in fiercely determined language. “We do not pay attention to the propaganda of the enemy, because Syria is the front line of the resistance and this reality is undeniable,’’ he said. “We have a duty to defend Muslims because they are under pressure and oppression.” Suleimani was fighting the same war, against the same foes, that he’d been fighting his entire life; for him, it seemed, the compromises of statecraft could not compare with the paradise of the battlefield. “We will support Syria to the end,” he said. ♦