Back to publications

The Leader of ISIS is Dead, but Are Targeted Killings Effective?

10 Feb 2022
Short Read by Graig R. Klein

The 2 February 2022 U.S. Special Forces operation against Abu Ibrajim al-Hashimi al-Qurayshi, the leader of ISIS, again raises questions about the impacts and effectiveness of counterterrorism strategies which target terrorist group leaders. Targeted killings, or ‘decapitation strikes’, against terrorists are an increasingly common tactic in U.S. counterterrorism. In general, for any counterterrorist or government, capturing is often preferred to killing so that suspects can be interrogated while killing suspected terrorists prevents them from striking, but dead men also tell no tales.” Statements by the U.S. Department of Defense claim the goal was to capture him, but like ISIS’s previous leader, Abu Bakr al-Baghdadi who was surrounded by U.S. forces on 27 October 2019, al-Qurayshi detonated a suicide bomb killing himself and family members rather than face capture.

A balance of excitement and trepidation have been voiced across the counterterrorism world. Conjecture about the consequences, or lack thereof, of this U.S. counterterrorism strike on ISIS’s near-term operations, ability to conduct terrorist attacks, and long-term sustainability are not new. Similar thinking followed the announcement of the successful counterterrorism operation against ISIS’s former leader al-Baghdadi and al-Qaeda’s leader Osama bin Laden on 2 May 2011. But what does scholarship on this strategy suggest?

Research on the impact and effectiveness of targeted killings and leadership decapitation strikes shows why balanced expectations are necessary. Although targeted killings have become a central tool in counterterrorism strategy, their effectiveness remains debated. Three potential impacts of targeted killings and leadership decapitation strikes center the debate arguing they may have the following impacts: 1) to decrease the terrorist group’s capabilities, 2) to increase group’s terrorist attack frequency, and 3) to serve as a radicalisation catalyst.

I discuss these competing impacts and the ensuing debate on the effectiveness of targeted leadership strikes. I then apply these lessons to an analysis of ISIS terrorist attack data from the Global Terrorism Database (GTD) and assess how al-Qurayshi’s death could influence the trajectory and capabilities of ISIS’s terrorism. By comparing trends in ISIS terrorism before and after the decapitation strike against al-Baghdadi, the analysis points to three possible short-term effects of al-Qurayshi’s death: the frequency of suicide bombings and other attacks using explosives may decrease, the use of firearms for terrorist attacks may increase, and there may be a lull in the frequency and number of ISIS terrorist attacks over the next few months. Combined, these might signal an opportunity for the U.S. and allies to land a serious blow to ISIS before its new leader consolidates power and reaffirms ISIS’s brutality.

Decrease Capabilities

Killing terrorists can decrease group resources, human capital and increase the costs of participating in terrorism or being a group member. Consequently, the quality of terrorist attacks often decreases. Attack quality most notably diminishes after mid-level leaders are killed. These negative effects could be multiplied if targeted strikes are against high-skilled group members. This may be a direct consequence of high-skilled terrorists, such as bomb makers, being in the crosshairs of decapitation strikes. Existing evidence shows that terrorist groups practicing suicide terrorism tend to use the tactic less following targeted killings.

Targeted killings may force terrorist groups to mobilise resources toward security and protection and away from attack planning. As targeted killings rely on complex intelligence, they can lead to paranoia in surviving, or new, terrorist group leaders and concerted efforts to identify moles inside the group and civilian informants. For example, after several AQAP commanders were killed in targeted strikes over a short period of time in 2015, the group looked for spies within its ranks and summarily executed two members for spying. ISIS exhibited similar paranoia following a string of U.S. drone strikes in the spring of 2016 that killed several high-value members, including the senior commander Abu Hayjaa al-Tunsi. Internal investigations resulted in the execution of at least 43 alleged spies from April to June 2016.

Shifting resources can also lead to simpler attacks, like armed assaults rather than using explosives. Or it can shift terrorists’ target selection toward civilian or other soft targets. This shift in target selection is observed in Somalia where U.S. strikes against al-Shabaab tend to trigger attacks against civilians. Changes in attack type, weapon, or target may be tactical deviations designed to avoid further detection and future targeted killing operations. This underscores the strategic decision-making of terrorist groups and the logical nature of terrorism.

The potency of targeted killing and leadership decapitation in diminishing terrorists’ capabilities can be mitigated by the terrorist group’s organisational structure and network. If the terrorist group maintains a cadre of experienced and capable fighters or has an existing line of succession, targeted killings have minimal impact on group capabilities. Larger and older terrorist groups are better able to survive leadership targeting, perhaps because they have better groomed successors or a larger cadre of high-level members ready to take the reins of leadership.

Increase Attack Frequency

When targeted killings or decapitation strikes focus on high-value targets, they can act as a deterrent and are expected to shift group activity away from attack planning and toward their own security. As a result, the frequency of attacks is anticipated to decrease. But, although targeted killing can decrease the quality of subsequent terrorist attacks, research finds it actually tends to increase the number of terrorist attacks. The increase could be a tit for tat battle in which terrorist groups feel the need to hit back at the counterterrorist. Boaz Ganor, Director of the International Institute for Counter Terrorism in Israel, calls this the Boomerang Effect.”

Radicalisation Catalyst

The collateral damage inflicted by targeted killings, primarily civilian casualties, also appears to play a role in their effectiveness. The potential of blowback – increased terrorist group recruitment and radicalisation following targeted killings – is one of the leading criticisms of targeted killings, particularly for drone strikes. For example, Israeli targeted killings resulting in unintended deaths led to upticks in Palestinian suicide bombings compared to when only the intended target was killed. For the existing terrorist group rank and file members, targeted killing can increase their resilience, reduce dissatisfaction and dissent, and thus unify the group and harden members’ commitment.

Targeted killings can be an effective radicalisation catalyst because victims can be idolised as martyrs. Without doubt, al-Qurayshi is now viewed as a martyr and martyrs often serve as radicalisation catalysts. Terrorist groups strategically develop ideological narratives around the fame, charisma, and selflessness of martyrs and then use these folklores to recruit and radicalise new supporters. For example, recruiters for the Islamic Jihad Movement in Palestine attend funerals for Palestinians killed by Israeli counterterrorism actions to recruit support and conscript new fighters. During The Troubles in Ireland, Provisional IRA recruitment routinely increased following excessive and indiscriminate British counterterrorism operations. In general, while targeted killings can eliminate specific threats or reduce a terrorist group’s skill-sets or capabilities, it risks generating a backlash that increases group membership and recruitment. Yet, a survey of 500 detained terrorists in Pakistan and interviews in North Waziristan suggest the feared blowback created by civilian casualties from targeted killing by drones strikes is overblown and not a significant factor in militant recruitment. Civilian casualties, exposure to violence, and the resulting harms to local communities does increase anger and hatred of the U.S., local, and national partners, which could become future grievances and motivations in radicalisation processes, but the immediate or short-term blowback may be minimal. 

What this could mean for ISIS

Reflecting on the last time ISIS’s leader was killed could help identify potential consequences of the 2 February operation targeting al-Qurayshi. On 31 October 2019, four days after al-Baghdadi died in a U.S. counterterrorism operation, al-Qurayshi was named the new leader of ISIS. The quick announcement of al-Qurayshi is important in relation to research on targeted killing and decapitation strikes as this type of counterterrorism appears to have a limited effect on terrorist groups with strong organisational cultures. ISIS’s highly bureaucratic and government-like organisational structure is well documented and the quick appointment of al-Qurayshi was a public signal that ISIS has the capability to remain a global threat.

To assess the impact al-Qurayshi’s death could have on ISIS terrorism in Syria and Iraq, we can analyse terrorist attack data and identify changes in patterns before and after al-Baghdadi’s death. Using terrorist attack data on Islamic State of Iraq and the Levant (ISIL) from the GTD, several potential effects of targeted killing and decapitation strikes highlighted above can be investigated specifically surrounding al-Baghdadi’s death and ISIS terrorism. GTD data is only available through the end of 2019, which makes this a short-term impact investigation. This restricts the data to reflect ISIS terrorism in Syria and Iraq while omitting affiliates’ and branches’ violence. Doing so results in 6,863 terrorist attack from 7 April 2013 (beginning of al-Baghdadi’s official leadership) to 31 December 2019.

ISIS did not claim responsibility for all these attacks. Claiming credit for terrorist attacks can be a strategic calculation by perpetrating groups, including by ISIS. Under al-Baghdadi’s leadership, 43% of ISIS terrorist attacks in GTD are claimed by the group, whereas in the first months of al-Qurayshi’s leadership, ISIS only claimed 16% of the attacks. To account for this and avoid missing important patterns that could be camouflaged by assessing all attacks instead of only those claimed by ISIS, I look at patterns in all ISIS terrorist attacks, in attacks claimed by ISIS, and attacks perpetrated but not claimed by ISIS. In all three sets of terrorist attacks, the targeted killing operation against al-Baghdadi had consistent short-term effects on the use of suicide bombings, the type of weapon used in attacks, and the frequency of attacks.

ISIS & Decreased Capabilities

In considering signs of decreased capabilities, I looked for changes in the frequency of suicide bombings, type of weapons used, the number of casualties, and types of attack targets.

Suicide Bombing

As discussed above, researchers have given particular attention to the impact of targeted killings on suicide bombings. Depending on the type of terrorism campaign, specific terrorist group studied, and local dynamics, targeted killings can increase or decrease the use of and frequency of suicide bombings. When looking at ISIS’s use of suicide bombings under al-Baghdadi’s leadership, GTD reports that 10 percent of ISIS attacks were suicide attacks (680 of the 6,802 terrorist attacks). Following his death, in the first two months of al-Qurayshi’s leadership, 1.6 percent of ISIS terrorist attacks were suicide attacks (1 of 62 terrorist attacks). The dramatic reduction in suicide attacks reinforces ISIS’s short-term shift toward lower-skill and lower-cost tactics observed in the change in distribution of weapon type.

Only 7% of the suicide attacks under al-Baghdadi were claimed. The one suicide attack under al-Qurayshi was not claimed. Given the small sample of suicide attacks under al-Qurayshi, it is hard to draw concrete conclusions. The pre-existing low rate of claiming suicide attacks suggests the one unclaimed suicide attack maintains consistency in group strategy even though there appears to be short-term re-allocations of resources toward lower-skill tactics. This points to the likelihood of targeted killings having a greater short-term than long-term impact on ISIS in relation to suicide bombings.

Weapon Type

The type of weapons may also change if resources are shifted from bomb-making or coordinating high-risk or high-skill attacks to lower-skill attacks. From the beginning of al-Baghdadi’s leadership until his death, the two most common weapons used in ISIS terrorist attacks were explosives (65.5 percent of attacks) and firearms (11.5 percent). Another 20 percent of ISIS terrorist attacks used an unknown weapon (GTD could not determine the weapon type from the available information”). In claimed attacks, explosives were used in 78.8 percent of attacks, firearms in 10.2 percent, and unknown in 9.4 percent. In unclaimed attacks, explosives were used in 55 percent of attacks, firearms in 12.5 percent, and an unknown weapon in 28 percent. Following al-Baghdadi’s death, this changed. ISIS terrorist attacks from 31 October 2019 to 31 December 2019 more frequently used firearms (27.4 percent of attacks) and unknown weapons (35.5 percent) and less frequently used explosives (37.1 percent). The data suggest ISIS may have shifted to lower-skill or lower-cost weapons in the short-term. A similar change may occur over the next few months if ISIS shifts resources toward internal security, protecting high-value members from additional counterterrorism operations, or strategically altering tactics to limit monitoring and tracking.

Attack Target Choice

If al-Baghdadi’s death decreased ISIS’s capabilities, then the group may have needed to shift attacks from hardened targets to soft targets. That is, from military, police, or government targets to civilian or weakly protected infrastructure. Looking at ISIS terrorist attacks from the beginning of al-Baghdadi’s leadership to his death, there are not significant differences in attack targets before and after his death.

Number of Casualties

In line with the change in weapon type and reduction in suicide attacks, the number of casualties resulting from ISIS terrorist attacks was significantly lower in the early days of al-Qurayshi’s leadership compared to al-Baghdadi’s. Using firearms instead of explosives concentrates an attack’s radius of violence. From the data, the average number of casualties per ISIS terrorist attack was 11.2 under al-Baghdadi and 4.1 under al-Qurayshi. This dramatic difference is in part caused by several very high casualty terrorist attacks.

When narrowing the focus to 2018 and 2019, when ISIS terrorist attack casualty rates were more consistently lower than in previous years, the difference is not statistically significant; 4.1 casualties per attack under al-Baghdadi and 5.8 under al-Qurayshi. But the data show a more constrained ISIS in the first two months of al-Qurayshi’s leadership as the number of casualties per attack ranged from 0 to 18 whereas in the last 1+ years of al-Baghdadi, casualties per attack ranged from 0 to 110. Casualties per claimed and unclaimed attacks follow a similar pattern. In the last 1+ years al-Baghdadi’s leadership there were 7.8 casualties per claimed attack (range 0 to 110) and 3.8 per unclaimed attack (range 0 to 72). And in the first two months of al-Qurayshi’s leadership there were 7 casualties per claimed attack (range 1 to 17) and 3.6 casualties per unclaimed attacks (range 0 to 18). Targeted killings do not appear to alter ISIS terrorist attack casualty .

ISIS & Attack Frequency Leadership change resulting from the targeted killing also seems to impact the frequency of ISIS terrorist attacks. During al-Baghdadi’s leadership, when analysing ISIS terrorist attacks in GTD in chronological order, it shows that ISIS conducted a terrorist attack nearly every day. During his 2,393 days of leadership, GTD reports at least one terrorist attack on 1,882 days leaving 511 days without an attack. On average, there was 0.27 days in between ISIS terrorist attacks. Four times during his leadership, there was more than a one-week lull in ISIS terrorist attacks, three of these four times were in al-Baghdadi’s first year of leadership. And the two longest periods of time without an ISIS terrorist attack recorded by GTD occurred very early in his tenure. In GTD data, 10 days passed from the time al-Baghdadi assumed official leadership of ISIS until a terrorist attack. And after a terrorist attack on 22 April 2013, the next terrorist attacks (there were two) are not recorded until 11 May 2013.

Following al-Baghdadi’s death, the next ISIS terrorist attack is recorded four days later on 31 October 2019, coinciding with the announcement of al-Qurayshi’s as the new leader. Two interesting patterns emerge when looking at the frequency of ISIS terrorist attacks in the early days of al-Qurayshi’s leadership. First, the average number of days in between ISIS terrorist attacks increases to 0.85, meaning there is more consistently nearly one-day in between attacks. This is a statistically significant difference in time between terrorist attacks than under al-Baghdadi’s leadership. Second, and likely most significant for counterterrorism, the early days of al-Qurayshi also were when longer periods in between attacks occurred. In his first two months of leadership, there are two times where more than two days passed in between ISIS terrorist attacks, and both times were in the first three weeks of his reign.

This shared pattern suggests that leadership turnover in ISIS results in increased focused on organisational management, potential reorientation of resource distribution and allocation, and possibly coordinating tactical changes. These patterns are nearly identical when looking at the time between claimed attacks and unclaimed attacks for both al-Baghdadi and al-Qurayshi. There should be little expectation that al-Qurayshi’s death and leadership change spells disaster and demise for ISIS, but the terrorist attack data points to the upcoming weeks as a critical opportunity for counterterrorism efforts against ISIS as there may be a slight lull in their operations.

ISIS & Radicalisation Catalyst

GTD does not include information on terrorist group size and data on recruitment is notoriously challenging to measure. However, terrorist groups have repeatedly used footage of airstrikes and military operations in their propaganda to radicalise and recruit. ISIS too has used such footage on social media platforms and in their media publications like Dabiq. Several interviews with imprisoned ISIS fighters suggest it works. Some fighters joined ISIS specifically seeking “revenge for international airstrikes.” Footage of the al-Qurayshi raid may be used for propaganda and recruitment and may help grow the size of ISIS’s rank and file supporters, members, and recruits.


Counterterrorism is always a high-risk endeavor. It is also unquestionably a necessary endeavor to improve local, regional, and global security. Removing ISIS’s leader from the battlefield, particularly at a time when ISIS has shown signs of resurrecting their territorial ambitions and threat-level, including at the recent al-Haskah prison attack, is certainly a celebratory counterterrorism success. But, as many analysts and experts have warned, the celebration should be tempered because it does not signal the demise of ISIS. Research on the impact and effectiveness of targeted killings and decapitation strikes and the ISIS terrorist attack data analysed in this perspective suggest that al-Qurayshi’s death could have limited short-term impacts on ISIS’s capabilities and violence, but it is unlikely to have a long-term detrimental effect on ISIS.