This article was first published in CTC Sentinel, the flagship publication of the Combating Terrorism Center at West Point.

One day in early November 2001, on a hillside south of Jalalabad, Afghanistan, Osama bin Laden bade farewell to three of his young sons. In the shade of an olive tree, he handed each boy a misbaha —a set of prayer beads symbolizing the 99 names of God in classical Arabic—and instructed them to keep the faith. The scene was an emotional one. “It was as if we pulled out our livers and left them there,” one of the boys would later recall in a letter to his father. Having taken his leave, bin Laden disappeared into the mountains, bound for a familiar redoubt known as the Black Cave, or Tora Bora in the local Pashto dialect.

The three boys who received the prayer beads that day would face three very different destinies. One, Bakr (also known as Ladin), would distance himself from al-Qaeda, both geographically and ideologically. Another, Khalid, would die protecting his father at their compound in Abbottabad, Pakistan, in May 2011. The third, Hamza, would vanish for years before reemerging in 2015 as the most likely candidate to reunite a fractured jihadi movement and lead al-Qaeda to a future still more violent than its past.

Groomed to Lead

Despite al-Qaeda’s generally dim view of women, it appears that Osama bin Laden respected and valued each of his wives. But he was surely familiar with the Qur’an’s warning that, “Try as you may, you cannot treat all your wives impartially.” It was well known that bin Laden had a favorite. This was Hamza bin Laden’s mother, Khairia Sabar, a child psychologist from the respected al-Hindi family of Saudi Arabia. The pair had been introduced when Saad, one of bin Laden’s sons by his first wife, Najwa al-Ghanem, had attended Khairia’s clinic to receive therapy for a mental disorder. Khairia was single, in her mid-30s, and in fragile health—an unpropitious situation for a woman in a conservative kingdom where teenage brides are far from uncommon. Bin Laden, by contrast, was seven years younger, the son of a billionaire, and already making a name for himself as a fundraiser for the mujahideen struggle against the Soviets in Afghanistan. Moreover, by this time, bin Laden already had two wives. But Najwa, the first of them, encouraged him to pursue Khairia, believing that having someone with her training permanently on hand would help her son Saad and his brothers and sisters, some of whom also suffered from developmental disorders.

Not surprisingly given Khairia’s age and state of health, she and bin Laden struggled to conceive. Over the first three years of their marriage, as bin Laden moved back and forth between Saudi Arabia and the theater of war in Afghanistan, she endured miscarriage after miscarriage. During this time, bin Laden added a fourth wife to the family—another highly educated Saudi woman, Siham Sabar. Then, in 1989, both Siham and Khairia bore him sons. Siham’s was called Khalid, a name that in Arabic means “eternal.” Khairia’s boy was named Hamza, meaning “steadfast.” Thenceforward, in accordance with ancient Arab custom, Khairia became known by the honorific Umm Hamza, the Mother of Hamza. The boy would remain her only child by bin Laden, but that fact has by no means diminished either Hamza’s importance or Khairia’s.

In 1991, reeling from a series of bloody embarrassments in Afghanistan and dismayed by the Saudi government’s increasing hostility toward him, bin Laden moved al-Qaeda’s base of operations to Sudan, just across the Red Sea from his home city of Jeddah. Among bin Laden’s inner circle of top lieutenants and their families, Umm Hamza soon developed a reputation for level-headedness and wise counsel. As bin Laden’s longtime bodyguard Abu Jandal put it, she was “respected by absolutely everyone.” In Sudan, Khairia set up an informal school to teach the wives and children of al-Qaeda members about Islamic theology, gave advice on religious matters, and from time to time even offered marriage counseling. At a time when al-Qaeda could easily have disintegrated under the weight of its forced exile and bin Laden’s growing fear of arrest or assassination, Khairia’s calm and optimistic influence played an important role in holding the organization together.

Hamza was seven years old when the regime of Omar Bashir finally caved to international pressure and expelled al-Qaeda from Sudan. bin Laden and his entourage decamped to Afghanistan, where they were offered safe haven first by local warlords and subsequently by the Taliban movement, which overran most of the country within a few months of bin Laden’s arrival. Al-Qaeda’s new hosts gave bin Laden the choice of several desirable residences, including a former royal palace. Characteristically, however, he chose instead a base in the mountains near Jalalabad consisting of concrete huts lacking power, water, and in many cases even doors. bin Laden eventually moved to Tarnak Farms, a camp complex outside Kandahar with almost as little in the way of creature comforts. Not everyone relishes this kind of austerity; while bin Laden was still in Sudan, his second wife, Khadija Sharif, had divorced him, citing the hardships of life in a militant camp. His first wife, Najwa, would finally leave him on the eve of 9/11. But Khairia and Siham—the mothers of Hamza and Khalid, respectively—were ready to go through significant privations for their husband, and both would be with him at the very end.

The Tehran Years

In Afghanistan, Hamza emerged as one of bin Laden’s favorite sons. Still not yet a teenager, he appeared in propaganda videos alongside his father, underwent assault training with al-Qaeda fighters, and preached fiery sermons in a young boy’s helium voice. In December 2000, aged 11, Hamza was chosen to recite a poem at the wedding of his 15-year-old brother, Mohammed. His assured performance transfixed the other guests; bin Laden family members would talk about it, and even have dreams about it, for years to come.

But already, Hamza’s time with his father was drawing to a close. On September 10, 2001, anticipating the backlash that would follow his latest and most outrageous assault on the United States, bin Laden ordered his wives and their younger children out of his Kandahar compound—a conspicuous target and one that had been bombed before—to seek shelter in Jalalabad, 350 miles northeast. There, al-Qaeda’s propagandists shot one last video featuring Hamza, in which the boy can be seen reciting a poem praising the bravery of Kabul’s Taliban defenders and handling wreckage claimed to be from a downed U.S. helicopter.

The video was, of course, a travesty. The Taliban, far from mounting a stalwart defense, were already being routed up and down the country, and the helicopter wreck, certainly not American, was most likely that of a Soviet gunship shot down before Hamza was born, probably with surface-to-air missiles supplied by the United States. As bin Laden made ready to ride south for his last stand at Tora Bora, he ordered his family east, over the border into Pakistan. This decision made sense. Al-Qaeda had found shelter there during and immediately after the war against the Soviets, and operatives like Khalid Sheikh Mohammed had long lived with impunity in Pakistani mega-cities like Karachi.

But 9/11 had changed this picture along with everything else. General Pervez Musharraf responded to the attacks by turning Pakistan into an enthusiastic supporter of the United States’ efforts against al-Qaeda and the Taliban. Faced with a rapidly narrowing range of risky options, al-Qaeda decided that its people, including bin Laden’s family, should leave Pakistan and seek refuge in the neighboring country of Iran.

The world’s foremost Shi`a stronghold may seem an odd destination for an organization populated by Sunni extremists, men who pepper their public utterances with slurs against Shi`a Muslims, calling them “rejectionists” and “apostates.” But in the fall of 2001, with support for the United States at an all-time high, Iran suddenly became the one place in the Muslim world where America’s writ could be counted upon not to run.

Inside Iran, Saif al-`Adl, a wily Egyptian ex-soldier who had been a pivotal figure in al-Qaeda since its inception, oversaw a secret network of safe houses. In the beginning, it seemed as if al-Qaeda had found at least temporary sanctuary. But Hamza nevertheless chafed against the constraints of this life in the shadows. In July 2002, he wrote a poem to his father, bemoaning the “spheres of danger everywhere I look” and asking, “What has happened for us to be chased by danger?” In his response, bin Laden did not sugar-coat matters for his 12-year-old son. “I can see only a very steep path ahead,” he wrote. “A decade has gone by in vagrancy and travel, and here we are in our tragedy… for how long will real men be in short supply?”

Further hardship lurked just over the horizon. For if Hamza and his family thought they had evaded detection, they were wrong. In fact, it seems that Iranian intelligence knew of al-Qaeda’s presence on the Islamic Republic’s soil right from the start. Around April 2003, the al-Qaeda members in Iran realized they were being watched and began to take steps to thwart Tehran’s monitoring. Fearing that al-Qaeda might slip through their fingers, the authorities initiated a dragnet that pulled in practically every al-Qaeda operative and family member in the country.

For the next few years, Hamza and his mother were held at a succession of military facilities in the Tehran area, some cramped and dingy, others spacious and relatively comfortable, but always separated from the outside world by high walls, razor wire, and surveillance cameras. Despite their tribulations, Khairia remained adamant that her son should receive the best possible education under the circumstances. Her own pedagogic efforts continued, and to supplement these, she solicited a group of bin Laden’s top lieutenants being held in the same facility, including al-`Adl, to educate Hamza in Qur’anic study, Islamic jurisprudence, and the hadith (alleged deeds and sayings of the prophet). Hamza is said to have become learned in each of these subjects.

Hamza matured in other ways, too. While still in captivity, he married the daughter of one of his teachers, the longtime al-Qaeda military commander Abu Mohammed al-Masri. Hamza’s new wife soon gave birth to a son and a daughter, whom they named respectively Usama and Khairia. Hamza told the elder bin Laden that “God created [my children] to serve you.” And he longed to rejoin his father. “How many times, from the depths of my heart, I wished to be beside you,” Hamza wrote in 2009. “I remember every smile that you smiled at me, every word that you spoke to me, every look that you gave me.”

Neither captivity nor fatherhood could dim the desire to follow in his father’s footsteps, which Hamza had shown from a precociously early age. On the contrary, as time went on, he grew ever more desperate to re-enter the fray. His greatest frustration, he told his father in a letter smuggled out to Abbottabad, was that “the mujahidin legions have marched and I have not joined them.” But bin Laden was determined to ensure a different destiny for his favorite son.

Waziristan

With so many senior al-Qaeda members in custody, Iran possessed huge leverage over bin Laden’s organization. By 2010, however, al-Qaeda had acquired a bargaining chip of its own in the shape of a captive Iranian diplomat sold to them as a hostage by Pakistani tribal elements. With the Haqqani Network acting as go-between, a prisoner swap was arranged. In August 2010, at the beginning of Ramadan, Hamza was released along with his mother, wife, and children. Two of his older brothers, Uthman and Mohammed, soon followed along with their own families. All those released made their way to Waziristan, where a sizable al-Qaeda contingent lived under the protection of various Pakistani militant groups.

The bin Laden family was spread across several countries. Abdullah, Usama’s eldest son, was living a “quiet life” as a businessman in Saudi Arabia. Another son, Ladin, previously imprisoned in Iran, had gone to stay with his grandmother’s side of family in Syria. Another, Omar, lived in Qatar for a time before moving to Saudi Arabia. bin Laden therefore had a number of possible places to send family members freed from Iran. He wanted his sons Uthman and Mohammed to stay in Pakistan, provided a “safe place” could be found for them. His initial plan on hearing of Hamza’s release was to try to have him sent to Qatar. Given that Hamza had been imprisoned in Iran from around the age of 14, it would be “difficult [for the United States or other countries] to indict him and to ask Qatar to extradite him.” Moreover, in Qatar, the home of Al-Jazeera, Hamza would enjoy relative freedom of speech, which he could exploit in order to act as a spokesperson for bin Laden’s brand of Islam, to “spread the jihadi doctrine and refute the wrong and the suspicions raised around jihad.” But Mahmud, bin Laden’s Libyan chief of staff—also known as Atiyya Abdul Rahman—balked at the idea of Qatar as a destination, on the basis that the small Gulf state, a U.S. ally, would hand Hamza over to the Americans. Ultimately, as will be seen, bin Laden followed Mahmud’s advice; but the suggestion that Hamza should act as a mouthpiece for jihadi dogma indicates that, despite their long separation, the father had more than an inkling of his son’s rhetorical abilities.

In Abbottabad, five hundred miles northeast of al-Qaeda’s Waziristan powerbase, bin Laden already had one grown son with him—Khalid, the son of his fourth wife, Siham, born in the same year as Hamza. Khalid served as the compound’s resident handyman and plumber. He also kept a cow he had bought from a local farmer and, like all of the men around bin Laden, was prepared to defend his father with deadly force. Khalid was useful to have around, to be sure, but hardly suited for leadership. Now, however, three more adult sons hid in Waziristan, awaiting their father’s call: Uthman, aged 27, Mohammed, 25, and Hamza, just 21. bin Laden made his choice. He ordered Uthman and Mohammed to go to Peshawar, 100 miles from their father. Khalid was to do the same, having been betrothed to a girl whose family lived there. But Hamza was to come to Abbottabad as soon as he could safely do so. As Khairia told him in a letter, “The father … asks God that he will benefit from you … He has prepared a lot of work for you.”

For a while, the portents seemed encouraging. Siham, Khalid’s mother, told Hamza of a “very good” dream in which “you were conducting Adhan [the Muslim call to prayer] from atop a very high building, in the same voice in which you said, ‘Stay strong my father, for heaven awaits us and victory is ours if God permits.’” This was a reference to the poem that Hamza had recited at his brother Mohammed’s wedding more than a decade previously.

As ever, security was the overriding factor, and bin Laden had already lost one son in Waziristan. Saad, a decade older than Hamza, had been imprisoned in Iran alongside his brothers, but by mid-August 2008, he had been set free (or had escaped, depending on which account one believes). Like Hamza, he made his way to Waziristan. Saad, characteristically, grew restless, perhaps as a result of the mental problems treated by Khairia back in Jeddah. Whatever the cause, Saad apparently behaved recklessly, showed his face once too often in public, and sometime in the first half of 2009, was killed by a U.S. missile. Mahmud, bin Laden’s chief of staff, told his commander in a letter that “Saad died—peace be upon him—because he was impatient.”

“We pray to God to have mercy on Saad,” bin Laden wrote. “And may He reward us with a substitute.”

For Hamza, Mahmud had nothing but praise. “He is very sweet and good,” he told bin Laden. “I see in him wisdom and politeness. He does not want to be treated with favoritism because he is the son of ‘someone.’”

Eager as he was for Hamza to join him, bin Laden was not going to allow the younger son to meet the same fate as the elder. He therefore issued operatives in Waziristan with strict instructions to keep Hamza indoors unless absolutely necessary and insisted on personally vetting the man assigned to guard his son. Under these strictures, which Mahmud likened to a “prison,” Hamza—usually as patient and level-headed as his mother—began to exhibit some of Saad’s petulance. Bin Laden relented a little, allowing Hamza to undergo shooting practice.

Bin Laden agonized over the decision to bring his son to his side. On the one hand, Hamza was the heir presumptive—the son of his favorite wife, charismatic and well-liked. He could be a great help to the organization. On the other hand, bin Laden’s own security situation, already precarious to begin with, had recently become yet more delicate, for the two Pakistani brothers who protected him and his family were dangerously close to burning out from stress. One of them, Ahmed, had contracted a serious illness that bin Laden feared might relapse at any time. They could hold out, bin Laden estimated, at most another few months. bin Laden needed to find replacements for the brothers as soon as possible, but his requirements were exacting. In order to blend in, the new protectors would need to be Pakistanis, fluent in local dialects. To avoid raising suspicions about the unusual size of the compound, they would need to have large families. And, of course, they would need to be absolutely trustworthy and relentlessly committed to the cause.

Mahmud would have his work cut out fulfilling such a tall order. In the meantime, however, bin Laden finally decided, despite the obvious danger, to have Hamza join him. By early April 2011, Mahmud had hatched a plan to make it happen. Hamza, with his wife and children, traveled south, through the badlands of Baluchistan. This was a roundabout route, to be sure, but it was safer than heading directly toward Abbottabad over the Khyber mountain passes. Once in Baluchistan, the plan was for Hamza’s party to rendezvous with Azmarai, one of al-Qaeda’s most seasoned and trusted fixers. Azmarai would arrange forward passage through Karachi and then by air or train to Peshawar. There, Hamza would meet another al-Qaeda operative who would send him on to Abbottabad when the time was right. To ease his brother through the inevitable checkpoints along the way, Khalid lent Hamza his fake ID and driver’s license. By late April 2011, plans were afoot, and Hamza waited only for a cloudy sky to speed him on his way. But it was not to be. Within a few weeks, his father was dead.

Heir Apparent

Hamza may have avoided death or capture in Abbottabad by weeks or even days. His brother Khalid was not so lucky; he died wielding an assault weapon in a futile attempt to defend his father against the superior numbers, tactics, and technology of the U.S. Navy SEALs. Hamza’s mother, Khairia, was taken into Pakistani custody in the early hours of May 2, 2011. Around a year later, she, Umm Khalid, and a dozen other bin Laden family members were deported to Saudi Arabia, where they live to this day in a compound outside Jeddah under what their lawyer describes as “very tight restrictions and security arrangements made by the Kingdom’s authorities,” including a ban on speaking publicly about their time in Pakistan.

Over the next four years, while Ayman al-Zawahiri took over as permanent emir of al-Qaeda, Syria and Iraq descended into barbarism, and the Islamic State spun out of al-Qaeda’s orbit, Hamza bin Laden remained silent. Then, out of the blue, in an audio message released in August 2015, al-Zawahiri introduced “a lion from the den of al-Qaeda”—a play on the name Usama, which means “lion” in Arabic. The next voice on the tape was that of Hamza. 56 He hailed the “martyrdom” of his father and his brother Khalid; praised al-Qaeda’s leaders in Syria, Yemen, and North Africa; lauded the attacks on Fort Hood and the Boston Marathon; and called for jihadis to “[t]ake the battlefield from Kabul, Baghdad, and Gaza to Washington, London, Paris, and Tel Aviv.”

Further statements appeared in May, July, and August 2016, prompting the U.S. State Department in January 2017 to place Hamza on its list of Specially Designated Global Terrorists. Two more messages then emerged in May 2017.

The theme of encouraging attacks on Jewish and Western interests is one to which Hamza has returned again and again in his messages. For example, the first of his May 2017 statements is entitled “Advice for Martyrdom-Seekers in the West.” Over footage of the aftermath of the Fort Hood massacre, a television reconstruction of events leading up to the 1993 World Trade Center bombing, and images connected with other attacks, Hamza encouraged jihadis all over the world to “Sell your soul cheaply for the pleasure of [God]” and urged them to read Inspire magazine, the online publication of al-Qaeda in the Arabian Peninsula (AQAP) that taught the Boston bombers how to turn a pressure cooker into a weapon. A caption in the video montage encourages “stabbing with knives and using vehicles and trucks” as an alternative to guns and bombs.

Strikingly, Hamza directs followers not to travel to theaters of war within the Muslim world, but instead to attack targets in the West and Russia. “Perhaps you are longing for emigration,” he says. “Perhaps you yearn for sacrifice in the battlefields. Know that inflicting punishment on Jews and Crusaders where you are is more vexing and severe for the enemy.” He urges “martyrs” that “the message you intend to convey through your blessed operation must be explained unequivocally in the media” and suggests talking points to align these explanations with al-Qaeda’s own propaganda.

In the same statement, Hamza sets up a hierarchy of targets to be attacked, starting with those who “transgress” against Islam (such as the editors of the French satirical weekly Charlie Hebdo), followed by Jewish interests, the United States, other NATO member states, and, lastly, Russia. It is noteworthy that Hamza accords attacks on Jewish interests a higher priority than those against Americans, whereas Osama bin Laden in his 1998 fatwa relating to “Jihad against Jews and Crusaders” depicted them as coequal targets. This hierarchy may reflect Hamza’s renewed emphasis on the Palestinian cause, dramatically stated in the title of his May 2016 statement, “Jerusalem Is a Bride and Our Blood Is Her Dowry.” However, this should not be taken as evidence that al-Qaeda is about to begin attacking Israel directly. It should be recalled that Osama bin Laden himself was quite cynical about the matter, admitting privately to his lieutenants that al-Qaeda’s rhetoric about Palestine was no more than “noise” designed to drum up popular support in the Arab world.

In two of his statements, Hamza, like his father before him, urges regime change in Saudi Arabia. The first, released in August 2016, bemoans AQAP’s ouster the previous April from Mukalla in Yemen, alleging that it was accomplished “with direct American participation.” 63 (In fact, Mukalla was liberated by a Saudi-led coalition of Arab forces.) The second statement was released during U.S. President Donald Trump’s state visit to Saudi Arabia in May 2017, although Hamza does not mention the trip in the text itself. In the latter statement, Hamza reiterates his call for the overthrow of the Saudi monarchy, claiming that the House of Saud has been doing the bidding of foreigners ever since the Kingdom’s founder, Ibn Saud, received British aid during World War I.

Hamza’s messages frequently repeat, almost word-for-word, sentences uttered by the elder bin Laden during al-Qaeda’s heyday in the late 1990s and early 2000s. This tendency can be heard, for example, in Hamza’s diatribes on the Palestinian Territories, on what he calls the “occupation” of Saudi Arabia, and on the idea that the United States is “stealing” the wealth of the Muslim world. (President Trump, no doubt unwittingly, played into the last of these narrative strands on his visit to Saudi Arabia, when he thanked King Salman for his “massive investment in America, its industry, and its jobs” and boasted of a new arms deal that would transfer a further $110 billion to U.S. companies.) Hamza even makes an effort to sound like his father, intoning his words with the same quiet intensity.

In his first statement, Hamza speaks of “following my father” by pledging allegiance to the leader of the Taliban. This is noteworthy in itself; whereas al-Qaeda’s other senior leaders pledge bayat to the emir of the organization (currently al-Zawahiri) who then swears fealty to the Taliban on behalf of al-Qaeda as a whole, Hamza gives his bayat directly to the Taliban leader, suggesting that, as the heir to bin Laden, he belongs to a higher class. Other aspects of the statements confirm the impression that Hamza is being elevated to leadership. In his earlier messages, al-Qaeda’s media arm referred to Hamza as a “Brother Mujahid,” a rank-and-file designation. But beginning with his two statements released in May 2017, the organization has started calling him “Sheikh,” a title reserved for its topmost brass.

None of Hamza’s messages have been accompanied by pictures of the man himself. In fact, the most recent known images are still those of Hamza sifting through helicopter wreckage in the weeks following 9/11, when he was just 12 years old; today, he would be 27 or 28. For a recent episode of 60 Minutes, CBS News commissioned a forensic artist, Stephen Mancusi, to take images of Hamza in his boyhood and subject them to an age-progression technique. The resulting portrait is of a young man who looks unsettlingly like his father around the same age, when he was raising money for the Afghan struggle against the Soviets. Another clue to Hamza’s appearance may come from the fact that he seems to have borrowed his half-brother Khalid’s Pakistani ID card for the abortive journey from Waziristan to Abbottabad. Khalid, as depicted in grisly photographs of his corpse lying on the stone floor of the Abbottabad house, shared his father’s long, thin nose and full lips. If Hamza does indeed resemble his father, and is willing in due time to show his face, no doubt the likeness will prove an asset in rallying jihadi support around al-Qaeda.

When Hamza’s first statement came out in August 2015, confidence in al-Zawahiri had reached an all-time low. It had just emerged that Mullah Omar had died in 2013, a year before al-Zawahiri had renewed al-Qaeda’s bayat to the Taliban leader. In other words, either al-Zawahiri had been unaware of Omar’s death—in which case he was too far out of the loop to lead—or he had known about it all along and had intentionally sworn allegiance to a dead man—a grave sin in al-Qaeda’s brand of Islam. This revelation brought dismay and ridicule from jihadis all over the world, at a time when the Islamic State was still capturing all the headlines and attracting the lion’s share of recruits. Raising the profile of the heir to bin Laden was thus an inspired move on the part of al-Zawahiri and the other al-Qaeda top brass. But Hamza’s return will have far broader and longer-term repercussions.

Future Standard Bearer of Global Jihad?

As the Islamic State continues to crumble, many of its adherents will be looking for new banners under which to fight. They are unlikely to pledge allegiance to al-Zawahiri, whom they see as an interloper unworthy of bin Laden’s legacy. It would be an understatement to say that al-Zawahiri lacks the charisma of his predecessor. Moreover, as an Egyptian, he will always struggle to inspire loyalty among other Arabs, especially those from the Arabian Peninsula.

Hamza, by contrast, suffers from none of these handicaps. His family pedigree, not to mention his dynastic marriage to the daughter of an al-Qaeda charter member, automatically entitles him to respect from every jihadi who follows bin Laden’s ideology, which includes every Islamic State fighter. As a Saudi descended from prominent families on both his father’s and his mother’s side, he is well-placed to pull in large donations from patrons in the Gulf, particularly at a time when sectarian fervor is running high in Saudi Arabia. It is significant in this regard that Hamza has returned to his father’s rhetoric castigating the House of Saud. As with bin Laden’s 1996 declaration of jihad, this is not just a political message; it is designed to inspire potential donors.

One final aspect of Hamza’s messages is noteworthy here. Unlike other leading al-Qaeda figures, he has never once explicitly criticized the Islamic State. True, he bemoans “strife” between the various groups fighting in Iraq and Syria and calls repeatedly for unity among jihadis to face down what he describes as a “unified enemy” of “Crusaders, Jews, Alawites, rejectionists, and apostate mercenaries.” But he carefully avoids naming the self-styled caliphate or its leaders. The Islamic State, for its part, reciprocates the favor; even as its propaganda castigates al-Zawahiri as a traitor to the cause, it never directly references Hamza. It is significant, too, that many Islamic State supporters who denounce “al-Zawahiri’s al-Qaeda” nevertheless profess admiration for Osama bin Laden. This is the best evidence that Hamza could be a unifying figure.

It is true that Hamza has never fought on the frontlines—something of which, as is seen in his letters to his father from captivity, he himself is painfully aware. This distinguishes him from the elder bin Laden, whose warrior myth was built on his exploits against the Soviets in Afghanistan in the 1980s. But it is not as much of a weakness as might be thought. Hamza is not coming out of thin air; he is the favorite son of the most famous jihadi in history. And in a culture where leadership typically descends through a bloodline, pedigree trumps experience. Moreover, while Hamza has not actually fought, he has been featured in al-Qaeda propaganda from a very young age, in videos that depict him as having been very close to his father. Perhaps most importantly of all, Hamza clearly has al-Qaeda’s senior leadership behind him. During his Iranian captivity, Hamza received training from some of al-Qaeda’s top operatives, including al-`Adl and al-Masri. Both of these men are now reportedly free and presumably available to give Hamza their counsel, something bin Laden himself lacked during the last nine years of his life.

Hamza’s ascendancy comes at a moment when al-Qaeda affiliates are growing in resources and influence across the Islamic world. Al-Nusra, the Syrian franchise now nominally subsumed into Hayat Tahrir al-Sham, may have more than 20,000 militants under its command. AQAP controls or has a presence in large swathes of Yemen’s coastline and highway network. Al-Qaeda in the Islamic Maghreb recently concluded a merger with several other factions, creating a jihadi conglomerate whose constituent groups collectively carried out over 250 attacks in 2016 alone. However, since AQAP’s threats against U.S. embassies in 2013, these franchises have apparently not sought to use their power to mount attacks against the West. While al-Zawahiri has mostly limited himself to threatening the United States rhetorically, if Hamza takes the reins, there is reason to think that could change, given that his messages repeatedly call for more attacks on American soil, praising previous atrocities like the Fort Hood massacre and the Boston Marathon bombing. As has been seen, Hamza has turned to his father’s well-worn anti-American rhetoric, accusing the United States of “occupying” the Arabian Peninsula and “stealing” Muslim wealth.

Many factors suggest that Hamza could be a highly effective leader: his family pedigree, his dynastic marriage, his longstanding jihadi fervor and obvious charisma, and his closeness to al-Qaeda’s most senior operatives. It remains to be seen how, exactly, the organization will make use of him, but it is clear that his star is on the rise. That should worry policymakers in the West as well as in the Muslim world.

This article is adapted in part from the author’s most recent book, Anatomy of Terror: From the Death of Bin Laden to the Rise of the Islamic State, which was published earlier this year by W. W. Norton & Company. The version published by The Daily Beast does not include citations. These can be viewed in the original version published by CTC Sentinel.