Suspected members of ISIS in a prison run by Kurdish-led forces in Syria, October 2019

Ivor Prickett/The New York Times/Redux

Suspected members of ISIS in a prison run by Kurdish-led forces in Syria, October 2019

On October 26 Abu Bakr al-Baghdadi, the leader of ISIS, died when he detonated a suicide vest after being cornered by US Delta Force soldiers in a tunnel in Idlib province, along the border with Turkey in northwestern Syria. Idlib is the last remaining rebel-held province, and Baghdadi was apparently hiding out among many other displaced Syrians, including jihadists, who were trying to survive the onslaught from Syrian president Bashar al-Assad’s forces and Russian air power. The CIA and US Special Forces had located him with the help of an ISIS informant cultivated by Kurdish intelligence officers in the US-aligned Syrian Democratic Forces (SDF). President Trump not only declared his death an American victory and a sign of ISIS’s demise but also claimed, without evidence, that Baghdadi had “died like a dog” and “like a coward,” and that he was “whimpering, screaming, and crying.”

Baghdadi was undeniably inspirational, audacious, and resourceful. Over the course of six years, beginning in 2013 when he announced its formation, ISIS under his leadership had energized transnational Sunni jihadism, supplanting al-Qaeda as its dominant force, attracting 40,000 foreign fighters from 110 countries, and taking control of large swaths of Syria and Iraq. He ruled with extreme brutality, mercilessly applying sharia law, frequently beheading Western captives and alleged traitors and apostates, and unabashedly using filmed ISIS violence and subjugation as a propaganda and recruiting tool. “Rape and sex played an important role in Islamic State selling points,” notes Daniel Byman in his authoritative and lively book Road Warriors: Foreign Fighters in the Armies of Jihad.

Between August 2014 and March 2019, however, a US-led coalition steadily rolled back the group’s territorial gains. Waged mainly by US warplanes in support of local ground forces—crucially Iraqi security forces and the SDF—Operation Inherent Resolve, as the coalition effort was called, also involved air strikes by the United Kingdom, France, Belgium, Denmark, the Netherlands, Canada, Australia, Saudi Arabia, the United Arab Emirates, Turkey, and Jordan.

After Baghdadi’s death, ISIS’s governing council swiftly released an audio recording announcing that Abu Ibrahim al-Hashemi Qurayshi would take his place. It warned the US, “Do not be happy.” Qurayshi’s name—a nom de guerre—is meant to convey that he is directly descended from the Prophet Muhammad and is thus qualified to become ISIS’s “caliph.” His nationality remains unknown, though the consensus among terrorism analysts is that he is an Iraqi. The highest priority of ISIS’s senior leadership was to signal to the group’s members and followers that Qurayshi would provide spiritual, strategic, and operational guidance to ISIS’s affiliates and followers just as Baghdadi had done, and that he would seek to restore the caliphate that Baghdadi had proclaimed in Iraq and Syria in June 2014, brutally expanded and sustained, and then lost. Their announcement was also intended to repudiate official American statements that ISIS is moribund.

Within ten days, ISIS affiliates in Afghanistan, Egypt, Pakistan, Somalia, and Yemen had pledged allegiance to the new leader. Yet Baghdadi’s death does create uncertainty about ISIS’s short- and medium-term effectiveness. Qurayshi is unknown and possibly untested. A comparison with al-Qaeda is useful here. As a result of its high-profile terrorist operations crowned by September 11, Osama bin Laden’s uncanny escape from US forces in Afghanistan across the Tora Bora mountains into Pakistan, and a devastatingly effective response to the US invasion and occupation of Iraq, al-Qaeda became an inspiration to aspiring jihadists worldwide. But the US killing of bin Laden in May 2011, his successor Ayman al-Zawahiri’s less than charismatic and unifying leadership, improved US targeting of al-Qaeda leaders (especially with drones), and the group’s subsequent disarray forced it to retrench and decentralize. This meant ceding more operational responsibility to regional affiliates.

The most potent of these had been al-Qaeda in Iraq (AQI), led by Abu Musab al-Zarqawi. After his death in 2006 in a US air strike, AQI and several other jihadist insurgencies in Iraq then declared themselves the Islamic State of Iraq (ISI). This expanded version of AQI controlled considerable territory but governed so imperiously and savagely that disaffected Iraqi Sunnis rebelled against it. Seizing on this “Sunni Awakening,” US forces partnered with anti-ISI Sunnis and in 2007 launched offensive operations against it—the “surge”—largely rolling back its territorial gains and hollowing out its leadership. Baghdadi became leader of what remained of the ISI in 2010. Syria’s civil war, which began in 2011, presented an opportunity for its revival. By the time al-Qaeda’s Afghanistan- and Pakistan-based central leadership decided to invest resources and stake a claim in Syria through Jabhat al-Nusra, its Syrian affiliate, ISI veterans were already building up what would become the Islamic State of Iraq and the Levant (ISIL), infiltrating and fighting for the Syrian opposition to Assad under Baghdadi’s leadership and rebranding the group the Islamic State in Iraq and Syria (ISIS).


Baghdadi decided that Zawahiri’s gradual approach—to overthrow Assad first, then move toward a regional caliphate—was too restrained and rejected his attempt to exclude ISIL from Syria and confine it to Iraq. ISIS split from al-Qaeda in February 2014; Baghdadi labeled al-Qaeda apostate and that June declared a worldwide caliphate centered in Iraq and Syria, renaming ISIS simply the Islamic State, though the group remained known as ISIS. Al-Qaeda’s reputation suffered, and the activity of those operating in its name diminished. ISIS became the foremost transnational jihadist group, gaining territory as well as regional and global influence. Al-Qaeda leaders had learned from Zarqawi’s experience a decade earlier, however, when he had overreached in proclaiming a caliphate in Iraq, and considered it premature for ISIS to establish one in Syria and Iraq. Those reservations proved to be well founded, as the Obama administration’s plan to break ISIS’s control of the territory it had claimed was continued and completed by the Trump administration.

Certainly Baghdadi’s death is a laudable achievement, even if it came after the United States and its allies had already obliterated ISIS’s caliphate. Whether it will be as detrimental to ISIS as bin Laden’s death was to al-Qaeda remains to be seen. As ISIS’s leader, Baghdadi seemed to emulate bin Laden, remaining in the shadows, making public pronouncements sparingly, and maintaining an ominous air of inaccessibility, mystery, and invincibility. He likewise inspired and directed attacks. But al-Qaeda had considerable depth within its upper ranks and, despite Zawahiri’s disappointing leadership and the US campaign of targeting its most important members, was able to maintain relative continuity.

ISIS seems to have fewer potential leaders. One possible consequence could be al-Qaeda’s recruitment of seasoned ISIS operatives, which would further weaken the group. But ISIS appears intent on countering any such development. In its acknowledgment of Baghdadi’s death, it also confirmed its intention to expand into Central Africa and Europe, threatening new attacks and characterizing the US as a “laughingstock” and Trump as “an old and crazy man…whose opinion changes between morning and evening.” Thus Baghdadi’s death has also increased uncertainty for Washington: US intelligence agencies are unsure how effectively Qurayshi will be able to generate and sustain organizational cohesion, international prestige, and operational momentum.

Decimating the leaders of terrorist groups—variously called “decapitation,” “high-value targeting,” or the “kingpin approach”—has been an important element of Western counterterrorism strategy. It is premised on the idea that a terrorist group’s senior leaders are essential to its operations. The strategy has worked in the short term, notably for the United States against al-Qaeda in Afghanistan and Pakistan and for Israel against Palestinian groups. But many analysts doubt its overall effectiveness. In Targeting Top Terrorists, one of the most rigorous studies to date, the political scientist and former US Army officer Bryan C. Price argues that “rather than reducing the terrorist threat, leadership decapitation is likely to increase the number of willing recruits for terrorist groups to exploit, allowing them to grow in size and popularity.” Decapitation will be more effective if a leader is crucial to a terrorist group’s operations, morale, and recruitment, and if leadership succession within the group is uncertain. It has become clear that eliminating a leader—even a singularly historic one like bin Laden—rarely defeats the group he leads.

The more independent the operational components (such as cells) of a terrorist group are, the less important senior leaders are to its viability. This point too has been hotly debated among counterterrorism analysts. In 2008 a feud arose between the psychiatrist and former CIA case officer Marc Sageman and the distinguished counterterrorism analyst Bruce Hoffman. Sageman maintained that jihadist terrorism was primarily carried out by groups that, though perhaps inspired by al-Qaeda’s vision, formed and operated primarily on a local basis as informal “‘bunches of guys,’ trusted friends, from the bottom up.”1 He suggested that self-starter terrorism was more the rule than the exception. (Although the term “lone wolf” has metaphorical appeal, it is often inapt, since many of the people it is used to describe get at least some reinforcement from a terrorist organization.) In a slashing review, Hoffman countered that al-Qaeda had reestablished a safe haven and physical base in the tribal areas of Pakistan, that al-Qaeda’s central leadership in Pakistan had increased its operational links with several of its regional franchises, and that al-Qaeda had regained some control over affiliated groups.2 His point was that even local operators almost always needed and got some outside practical assistance.

Neither Hoffman nor Sageman was completely wrong. The attack on the Charlie Hebdo offices in Paris in January 2015, for instance, was perpetrated by terrorists trained by al-Qaeda in the Arabian Peninsula and possibly facilitated by the group. But following the ascent of ISIS in 2013–2014, jihadist terrorist operations outside the Middle East tended to involve locals who were mostly just stimulated by ISIS rhetoric and public encouragement. Although the ISIS leadership in Iraq opportunistically claimed credit for these operations once their effectiveness became clear, Internet recruitment, indoctrination, and training have expanded self-starter terrorism.


The field of counterterrorism has thus moved away from static, rigid models. More recent analyses have sought to reconcile Sageman’s and Hoffman’s viewpoints. Assaf Moghadam, for instance, in Nexus of Global Jihad: Understanding Cooperation Among Terrorist Actors, emphasizes cooperative associations—formal and informal, face-to-face and virtual—that an ostensibly self-motivated terrorist might form, noting “the importance of network analysis as a fruitful methodology for studying terrorism.” For purposes of analyzing and countering terrorism, he concludes, there should be “no hard separations between types of cooperation. Instead, they should be seen as occupying a spectrum ranging from mergers, at the highest end, to transactional cooperation, at the lowest.”3 The term “lone wolf” does not appear in his book.

Sageman has continued to focus on individual actors. In his latest book, The London Bombings, however, he argues that the jihadist terrorist threat is “a hybrid, somewhere between an organized and a leaderless one.” Societal and political factors are critical to incubating extremists. They include close-knit Islamist communities, marginalization by the host country, burgeoning global hostility to Muslims, and direct contact with indoctrinated individuals. These do not require the concerted technical facilitation of a formal terrorist grouping or support network to generate “small group discussions among friends” who may then “acquire political and eventually radical ideas” and consolidate into “clusters” that take action.

In times of disruption, disarray, or disillusionment, a transnational terrorist group can increase its reliance on such people to help ensure its vitality. By late 2015, ISIS was under pressure from the US-led air campaign in Iraq and Syria. For well over a year, US warplanes had pounded its positions with nearly 10,000 air strikes, killing about 28,000 fighters. ISIS had lost 40 percent of the territory it held in Iraq and 20 percent of what it held in Syria. US special operations forces were also targeting ISIS leaders more successfully, killing its second-in-command, Abd al-Rahman Mustafa al-Qaduli, in March 2016. During this period, ISIS appeared increasingly inclined to try to salvage its prestige and its recruiting power by hitting relatively soft targets in European cities.

Abu Bakr al-Baghdadi
Abu Bakr al-Baghdadi; drawing by James Ferguson

The Paris attacks in November 2015, which killed 130 people, signaled a new phase of its campaign. Their purpose was to partially offset ISIS’s faltering effort to maintain a caliphate by launching attacks abroad so as to uphold its brand and increase its flow of recruits. According to the University of Maryland’s Global Terrorism Database, ISIS carried out more than 1,400 attacks and killed more than seven thousand people in 2016—a 20 percent increase from 2015. Between the Paris attacks and ISIS’s decisive defeat in Syria in 2019, there were, in addition to many ISIS-linked terrorist attacks within the greater Middle East, locally based attacks in Bangladesh; San Bernardino, California; Jakarta; Brussels; Orlando, Florida; Bangladesh again; Nice; Würzburg, Germany; Charleroi, Belgium; Moscow; St. Cloud, Minnesota; Berlin; London; Bangladesh a third time; Chechnya; Paris; eastern Russia; Manchester; London again; Barcelona; Surgut, Russia; Brussels again; London a third time; Marseilles; Nigeria; New York; Liège, Belgium; and Colombo, Sri Lanka. Facing major reversals in Iraq and Syria, the group appeared all the more determined to stay relevant and conspicuous by inspiring and facilitating terrorist attacks outside the Middle East.

Meanwhile, the US-led campaign against ISIS continued. By December 2017, ISIS had lost 95 percent of the territory it had controlled in Iraq and Syria, including two crucial hubs: Mosul, Iraq’s second-largest city, and the northern Syrian city of Raqqa, the caliphate’s designated capital. In 2018 the Kurdish-dominated SDF, aided by American air strikes and US Special Forces, led the assault on ISIS’s remaining strongholds in eastern Syria. By December of that year, ISIS held only a few villages on the Euphrates River, near the Iraqi border, and by March 2019 the SDF had mopped those up, leading to the surrender of thousands of ISIS fighters. Following Russia’s intervention in the Syrian conflict in September 2015, the Assad regime, supported by Iran, Russia, Hezbollah, and Iran-backed Iraqi Shia militias, regained military and political control of most of the other areas of Syria that ISIS or other Sunni opponents of the regime had controlled.

Idlib, where the US military eventually tracked Baghdadi down, still hosts an appreciable number of jihadists. (An estimated 14,000 to 18,000 ISIS fighters are still in Iraq and Syria.) Most of the US military personnel in Syria were deployed east of Idlib, and, alongside the SDF, which controlled northeastern Syria, functioned as a deterrent to ISIS’s reconstitution. In early October Trump ordered a substantial reduction of US forces in Syria, from over a thousand to five hundred, redeploying them farther south and acquiescing to Turkey’s expulsion of the SDF from border areas. The US appeared to be abandoning an important regional ally that had suffered a great many casualties—some 11,000 Kurdish SDF fighters died in the campaign against ISIS—for the US-led counterterrorism effort.

The abrupt shift in policy also left northeastern Syria chaotic, increasing jihadists’ freedom of action there and diluting any positive effect of Baghdadi’s death. Several hundred ISIS prisoners escaped from a detention center when Kurdish forces had to abandon it to deal with the Turkish invasion. The custody of another 10,000 remained compromised, as Turkish forces consolidated control over an area seventy-five miles wide extending nineteen miles south of the border, now secured by joint Turkish-Russian patrols under an agreement between Ankara and Moscow. In addition, the current political crisis and consequent instability in Iraq, as well as growing anger over Iranian influence there, is likely to increase the appeal of resurgent Sunni extremism.

In July 2016 al-Qaeda’s Syrian affiliate Jabhat al-Nusra was rebranded as Jabhat Fateh al-Sham, which in turn merged with several other groups to form Hay’at Tahrir al-Sham in early 2017. Through this group, which at one point fielded between 10,000 and 14,000 fighters, al-Qaeda has continued to be a significant force in Syria. Al-Qaeda and ISIS could reconcile and form a single organization in Syria, or reach a modus vivendi under which they would cooperate and coordinate. That would be a bad enough outcome. But the history of such groups suggests that one will dominate and defeat the other, and emerge stronger and more resolute, as in the cases of Hezbollah and Amal, the Tamil Tigers and their various rivals, and the Provisional Irish Republican Army and the Official IRA. Because of ISIS’s size and momentum—it has appreciably more operatives than al-Qaeda and has surpassed it in global influence and transnational operational capability—it would seem to be the likely victor. Though momentarily bruised, it could emerge stronger than it is now.

According to the most recent quarterly report from the Pentagon, the State Department, and USAID to Congress on US operations in Syria, the Defense Intelligence Agency assesses that Baghdadi’s death will “likely have little effect on ISIS’s ability to reconstitute,” and that the US pullback from Syria is affording ISIS “time and space” to rebuild and target the West.4 It will probably continue as a resilient insurgency in Iraq and Syria, and as a terrorist network extending to Afghanistan, Libya, Egypt, Yemen, Somalia, West Africa, Southeast Asia, Europe, and even the United States. Assuming that the group manages to have a reasonably smooth leadership transition, Trump’s gratuitous belittling of Baghdadi could inspire more recruits, inflame jihadist passions, and increase the likelihood of anti-American reprisals by ISIS both in the Middle East and farther afield—including in the US.

Even if ISIS remains largely suppressed in Syria and Iraq, it has shown that it can bide its time and intensify operations elsewhere. In his last public statement before his death—his first in five years—disseminated in an eighteen-minute video on April 29, Baghdadi cast the devastating bombings in Sri Lanka on April 21, which killed at least 250 people, as revenge for the coalition’s seizure of Baghouz, ISIS’s last outpost in Syria. “Our battle today is a war of attrition to harm the enemy, and they should know that jihad will continue until doomsday,” he warned, noting that the group had executed ninety-two attacks in eight countries even as it lost ground in Syria.

The Trump administration’s partial withdrawal has been a boon to ISIS, not least in demonstrating the United States’ tenuousness as an ally to anti-ISIS forces. Recent history suggests a possible pattern: the complete US withdrawal from Iraq in 2011, which Iraq insisted on but the Obama administration tried to curtail, facilitated the resurgence of the ISI in the form of ISIS and advanced the spread of extremist ideology. The Trump administration—facing backlash from Congress, within the Pentagon, and from allies—has recently restored some US troops to the region and allowed them to help Kurdish fighters repel ISIS attacks there. It is unclear whether the administration is now walking back Trump’s withdrawal, but it’s obvious that even though it managed to kill Baghdadi, the US has no coherent strategy for Syria.

—December 18, 2019