Situational Crime Prevention and Terrorism: An Assessment of 10 Years of Research

Abstract

This study systematically reviews the Situational Crime Prevention (SCP) and terrorism literature published between 2006 and 2016. We examine several variables related to the backgrounds of authors, publication outlets, methods used, and countries and terrorist groups focused upon in these studies. We also investigate if studies have tested the pillars of terrorism opportunity relating to weapons, targets, tools, and facilitating conditions. We find a strong literature and much support for SCP’s claims in the terrorism context. We highlight some data and method obstacles in fully evaluating SCP’s EVIL DONE, MURDEROUS, and ESEER frameworks and tools pillar, and suggest a need for more multivariate designs. We end by identifying underexplored substantive issues that deserve more attention, such as possibly refining EVIL DONE and to more fully address displacement versus adaptation processes.

Keywords

crime control policy crime prevention homeland security terrorism terrorism prevention

Introduction

This study systematically reviews the Situational Crime Prevention (SCP) and terrorism literature published between 2006 and 2016. Studying terrorism has historically been the domain of psychologists and political scientists who have highlighted the individual dispositions and collective grievances of ideologically motivated actors. Only recently have criminologists begun to seriously focus their attention on issues of terrorism and homeland security (Freilich & LaFree, 2015; LaFree & Freilich, 2016, for exceptions, see Hamm, 1993; Smith, 1994). Some crime scholars remain interested in the applicability of traditional sociological theories of crime to terrorism (LaFree & Dugan, 2004; Rausch & LaFree, 2007; Rosenfeld, 2004), while others eschew the intractability of individual behavior and note the promise of preventing terrorist crimes by altering their environments. Enviromental perspectives of crime illuminate temporal and spatial elements that may shape offender decision making and patterns of victimization, a different complementary approach to addressing the many complex psychological and social causes and correlates of terrorism. These place-based crime prevention approaches have been developed to reduce situated opportunities for committing crime and include crime pattern theory (Brantingham & Brantingham, 1990), routine activities theory (Cohen & Felson, 1979), hot spot analysis (Sherman, Gartin, & Buerger, 1989; Weisburd & Green, 1995), and crime prevention through environmental design (CPTED; Cozens, 2011), among others.

Incorporating key tenets of these theories, Situational Crime Prevention (SCP) seeks to understand how actors take advantage of situated opportunities to commit crime. Based on particular crime patterns, intervening SCP mechanisms are designed and introduced to manipulate environments by increasing risks and efforts needed to successfully commit crime, thereby reducing rewards and provocations of crime and removing excuses used to justify crime (Clarke, 1980; Freilich & Newman, 2017).

In 2006, Clarke and Newman (2006) published their book titled Outsmarting the Terrorists in which they argued that SCP interventions could be used to reduce terrorist attacks. Others noted than an SCP approach could also complement “root causes” approaches by managing the problem and buying valuable time allowing for peace processes to emerge (Freilich & Newman, 2009). Although Clarke and Newman’s (2006) book was mostly conceptual, a growing body of work has extended, critiqued, and tested their ideas in the ensuing decade. Scholarly articles examining SCP’s applications to terrorism have been published in criminal justice, terrorism, and other disciplines journals, while an increasing number of graduate students have investigated Clarke and Newman’s SCP and terrorism claims in master’s theses and doctoral dissertations.

SCP has been found to be an effective approach to reducing crime (Clarke, 1997; Guerette & Bowers, 2009; Hesseling, 1994; Weisburd, Wycoff, Ready, Eck, & Hinkle, 2006), but its applicability to terrorism has yet to be systematically evaluated. Considering its potential for reducing terrorism, we suggest that it is now appropriate to take stock of the first 10 years of the SCP and terrorism literature by outlining what has been accomplished and learned. Just in the period since Clarke and Newman’s (2006) call to apply SCP to terrorism, over 60 works have been published on this topic. To date, however, researchers have yet to provide a thorough review of this growing literature.

The purpose of this study is to conduct a systematic review of journal articles, book chapters, doctoral dissertations, and master’s theses examining SCP and terrorism that were published between the issuance of Clarke and Newman’s book (March 2006) and March 31, 2016. Given the state of the SCP and terrorism literature, it is not yet possible to conduct a meta-analysis where effect sizes are summarized across a range of quantitative studies. Instead, we conduct a systematic review, in which we identify relevant works using well-defined inclusion criteria and then code key attributes about them (Hemingway & Brereton, 2009).

We examine several variables related to the backgrounds of authors, publication outlets, methods used in the study, whether the study empirically examines the pillars of terrorism opportunity, and which countries and terrorist groups it focused upon. The remainder of our paper unfolds by first providing an overview of Clarke and Newman’s SCP and terrorism claims. Second, we discuss the issues examined and how we identified and analyzed key attributes from the relevant studies. Third, we present our findings and attempt to make sense of them. Our goal is to identify the strengths of these studies and the lessons learned from research on this topic during the last decade, as well as highlight the gaps and weaknesses of this literature. We end by providing suggestions for future research to address these gaps and to extend the application of SCP to terrorism.

Outsmarting the Terrorists Through SCP

In Clarke and Newman’s (2006) Outsmarting the Terrorists, the authors contend that established techniques of SCP can be applied to terrorism due to the similarities in ideological crime and other nonideological forms of crime. For instance, both crime and terrorism often involve a combination of motives, some level of determination and planning, peer networks, and, importantly, the exploitation of opportunities. Therefore, limiting opportunities available for ideologically motivated offenders to commit crime will in theory reduce future terrorism. Importantly, the research lens of SCP extends to the situated context of terrorist events rather than solely focusing on the backgrounds of individual offenders. SCP proponents assume that there will usually be an unlimited supply of potential terrorists who adhere to aggrieved ideological movements and whose goals are difficult to satisfy. Thus, many counterterrorism policies currently in use that aim to eliminate (e.g., drone strikes) or incapacitate terrorists (e.g., Guantanamo Bay) may be limited in their effectiveness for reducing terrorism.

Clarke and Newman (2006) argue that the opportunity structure of terrorism consists of four pillars, including targets, weapons, tools and facilitating conditions, and that the key is to examine how these pillars will help or hinder preparation for and execution of terrorist acts. The first pillar of opportunity involves the selection of targets. A common critique of the application of SCP to terrorism is that it is impossible and too expensive to protect all of the potential targets that terrorists may choose (Mueller, 2010; Stewart, 2008). However, Clarke and Newman (2006) counter that not all targets need to be protected because they are not all equally at risk. Some targets are more attractive to terrorists, and thus more at risk and in need of protection.

Building upon prior successes in applying SCP interventions for identifying products most vulnerable for theft (Felson & Clarke, 1998), Clarke and Newman (2006) devised a terrorism target risk assessment template, known by the acronym EVIL DONE. Targets that are more exposed, vital, iconic, legitimate, destructible, occupied, near, and easy are thought to be more at risk for a terrorist attack. Those that stand out and are more visible are considered more exposed targets. Vital targets, such as power plants or water supplies, are those that provide important necessities for society. Iconic targets are symbolically significant to society (e.g., White House), while legitimate targets are seen as more acceptable or deserving of an attack (e.g., militaries of perceived enemies) compared to others (e.g., children). Meanwhile, destructible targets are easier to destroy than other possible targets. Targets that contain more potential victims, or are more occupied, are also more at risk for attack. In addition, targets that are closer, or nearer, to the terrorists and easier to travel to are more at risk. Also, targets that have less security or are easy to access are evaluated as increasingly vulnerable. Finally, in addition to these eight target dimensions, the expected loss, in terms of fatalities and injuries, upon attack must be considered. Careful observation of these dimensions for all potential targets is required to identify those most vulnerable to attack. It is these targets that must be prioritized for extra protection and situational interventions.

The second pillar of opportunity refers to the weapons selected by terrorists. Clarke and Newman (2006) contend that just as all targets are not equally vulnerable, all types of weapons are also not equally likely to be utilized by terrorists. Here, too, Clarke and Newman summarize the key dimensions of this pillar of opportunity with an acronym MURDEROUS. Clarke and Newman believe that terrorists are more likely to rely on weapons that can be employed in a variety of situations (multipurpose), are easy to hide (undetectable), easily handled and carried (removable), can cause deaths and injuries (destructive), are fun to use (enjoyable), can be counted on to work (reliable), are easily available for use (obtainable), are simple to use and do not require much training (uncomplicated), and, to the extent possible, minimize the danger to the terrorist using it (safe). It is suggested that observing and measuring how these particular dimensions are perceived by terrorists to be advantageous for specific types of crimes can be helpful in identifying the weapons most sought after by terrorists. Strategies can then be devised to prevent terrorists from accessing these weapons.

The third pillar of terrorist opportunity according to Clarke and Newman (2006) include the tools that terrorists use to carry out their planned strikes. Common tools encompass money, which may be used, for instance, to purchase weapons, vehicles, and other travel devices that might allow terrorists to gain access to targets, or the purchase of fraudulent identifications (e.g., passports, social security cards, or driver’s licenses) that would allow for ease of mobility without arousing suspicion. Terrorists who have access to these tools will be more likely to succeed in carrying out their attacks. Effective situational interventions would concentrate on altering the terrorist opportunity structure by denying terrorists access to these tools.

Finally, the fourth pillar of opportunity refers to broad facilitating conditions that allow terrorism to occur. Facilitating factors are more distal factors that can have important situational implications in terms of the availability of tools and weapons to the terrorists (Freilich & Chermak, 2009; Wortley, 1996, 2002). Clarke and Newman rely on another acronym, ESEER, to summarize five types of factors that serve as facilitating conditions, including easy conditions (e.g., a government rife with corruption where bribery is expected), safe conditions (e.g., a nation with lax identification requirements), excusable conditions (e.g., overreactions by governments that play to terrorists’ advantage), enticing conditions (e.g., community support for terrorists actions), and rewarding conditions (e.g., financial or religious rewards). Examples of facilitating conditions include laws that dictate accessibility to weapons, levels of border security, banking security, and immigration policies. Again, these more distal factors have situational implications in their facilitation of opportunities that make it easier or more difficult to commit terrorist attacks.

There are a variety of ways to anticipate how terrorists might exploit the four pillars of opportunities. Thus, Clarke and Newman (2006) suggest that it is important to “think like a terrorist” and consider varying crime-specific opportunities available for committing terrorism, as each form of terrorism, whether a suicide bombing, hijacking, or shooting, has different opportunities and vulnerabilities for terrorists to exploit. Because different types of terrorism have varying opportunity structures, successful intervention against one form of terrorism attack will usually not result in displacement to another. Once the opportunities are identified, SCP relies upon 25 techniques of situation prevention to devise or identify possible interventions to prevent future attacks (Cornish & Clarke, 2003; Freilich & Newman, 2017).

Table 1 lists SCP’s 25 techniques that seek to increase the effort required to conduct crimes, or aim to reduce cues that situationally may increase offenders’ criminal motivations. Proponents of SCP call for copying or adapting from past successful SCP interventions or relying upon ingenuity to create new ones that can be implemented to reduce future attacks (Eck, 2002a, 2002b; Ekblom, 2012). After an intervention is implemented, it is then important to evaluate its effectiveness.

Table 1.

Twenty-Five Techniques of SCP (http://www.popcenter.org/25techniques/).

Increase the effort	Increase the risks	Reduce the rewards	Reduce provocations	Remove excuses
1. Target harden Steering column locks and immobilizers Antirobbery screens Tamper-proof packaging	6. Extend guardianship Take routine precautions: go out in group at night, leave signs of occupancy, carry phone “Cocoon” neighborhood watch	11. Conceal targets Off-street parking Gender-neutral phone directories Unmarked bullion trucks	16. Reduce frustrations and stress Efficient queues and polite service Expanded seating Soothing music/muted lights	21. Set rules Rental agreements Harassment codes Hotel registration
2. Control access to facilities Entry phones Electronic card access Baggage screening	7. Assist natural surveillance Improved street lighting Defensible space design Support whistleblowers	12. Remove targets Removable car radio Women’s refuges Prepaid cards for pay phones	17. Avoid disputes Separate enclosures for rival soccer fans Reduce crowding in pubs Fixed cab fares	22. Post instructions “No Parking” “Private Property” “Extinguish camp fires”
3. Screen exits Ticket needed for exit Export documents Electronic merchandise tags	8. Reduce anonymity Taxi driver IDs “How’s my driving?” decals School uniforms	13. Identify property Property marking Vehicle licensing and parts marking Cattle branding	18. Reduce emotional arousal Controls on violent pornography Enforce good behavior on soccer field Prohibit racial slurs	23. Alert conscience Roadside speed display boards Signatures for customs declarations “Shoplifting is stealing”
4. Deflect offenders Street closures Separate bathrooms for women Disperse pubs	9. Utilize place managers CCTV for double-deck buses Two clerks for convenience stores Reward vigilance	14. Disrupt markets Monitor pawn shops Controls on classified ads. License street vendors	19. Neutralize peer pressure “Idiots drink and drive” “It’s OK to say No” Disperse troublemakers at school	24. Assist compliance Easy library checkout Public lavatories Litter bins
5. Control tools/weapons “Smart” guns Disabling stolen cell phones Restrict spray paint sales to juveniles	10. Strengthen formal surveillance Red light cameras Burglar alarms Security guards	15. Deny benefits Ink merchandise tags Graffiti cleaning Speed humps	20. Discourage imitation Rapid repair of vandalism V-chips in TVs Censor details of modus operandi	25. Control drugs and alcohol Breathalyzers in pubs Server intervention Alcohol-free events

Note. SCP = situational crime prevention.

The Current Study

This study examines several attributes of published works on topics related to SCP and terrorism. We begin by describing the authors of studies on SCP and terrorism. As noted, criminologists arrived relatively late to the scholarly study of terrorism, so we are curious to learn if only trained criminologists have relied upon SCP’s framework or if academics from other disciplines, like political science or psychology, are also making use of it. Patterns of solo authorship and collaborative efforts are also explained. Relatedly, we note the extent to which certain authors publish on the topic of SCP and terrorism. Silke’s (2001) important review of the terrorism literature more generally established the relevance of these questions, as collaborative works may involve authors with varying skillsets that allow for more innovative studies to be conducted compared to those done by lone scholars. Similarly, academics publishing consistently in one area allow for expansion of previous research to create an evolving and more encompassing body of work. In other words, these scholars usually extend their past research step by step to cumulatively make a bigger impact in this area, compared to academics who conduct a single study and then turn their attention to a new field. A literature dominated by transient authors may, thus, represent a less developed field. We recognize that a “transient” scholar could set forth a ground-breaking theoretical framework or conduct an innovative empirical study that fills a key void in the literature. But, generally, scholars conducting sustained research and systematically building upon prior work will reflect a more advanced field.

In addition to author attributes, our systematic review captures key details about the works published on SCP and terrorism. For instance, we explore the types of publications being authored by researchers on this topic, such as scholarly articles, book chapters, and graduate theses. Generally, peer-reviewed articles are considered to have undergone a more rigorous review, and therefore should have a higher quality than works published as chapters in edited volumes. Providing a snap shot of whether these works are published as books, articles, chapters, or theses will also allow us to make judgments about the overall status of this body of knowledge. We also explore when these works were published. Did Clarke and Newman’s (2006) work result in an initial burst of activity to explore their ideas that have since trickled off? Or, in contrast, has interest continued and even increased over time? We hope to provide clarity to this point. For those works published in scholarly journals, we are also interested in the disciplinary foci of these journals. That is, in addition to criminal justice journals, what other disciplines are publishing articles on SCP and terrorism?

Silke’s (2001) thorough review aptly stresses the weaknesses of terrorism research hinging on the lack of data-driven empirical works. A healthy body of research empirically tests core conceptual claims, discards those claims that are falsified, and refines those arguments based upon supportive and contrary evidence. A less developed and stagnant field, conversely, fails in this regard. Therefore, we examine the type of study the authors conducted, noting if it was theoretical, essay-based, or empirical, and, if empirical, whether it was a qualitative or quantitative study. For the quantitative studies, we examine whether the study included multivariate or only descriptive statistical analyses. We also document the sources of empirical data. Relatedly, as previously discussed, Clarke and Newman’s treatise called attention to the four pillars of the terrorism opportunity structure. Here we investigate if research has empirically tested their EVIL DONE, MURDEROUS, and ESEER templates and tools claims. Answering such questions should illuminate the rigor and replicability of this growing literature.

Finally, as SCP is a general approach that has wide applications across multiple contexts, we look to see which nations and which terrorist movements are mentioned in these studies to determine if, in fact, SCP has had a general reach and been applied to many nations and movements or, conversely, if this body of work has had a more limited focus. In the next section, we describe in more detail how studies included in the current research were identified and systematically reviewed.

Data and Method

The publications utilized in this review include scholarly journal articles, book chapters, MA theses, and PhD dissertations related to topics of SCP and terrorism. To obtain these publications, several indexes, including EBSCO Academic Search Premier, Criminal Justice Abstracts, and Google Scholar, were systematically searched. All publications that examined SCP and terrorism were deemed relevant and included as long as they were published after the publication of Clarke and Newman’s book in March 2006 and before March 31, 2016, thus covering a span of 10 years. Once the correct time period was specified in the searchable indexes, several key words were used in varying combinations to identify appropriate publications, specifically “situational crime prevention,” “SCP,” “environmental criminology,” and “terrorism.” This search method initially yielded a total of 69 scholarly works. However, upon further review and evaluation by the authors, nine of the publications were excluded from this study because they did not directly focus on SCP’s applications to terrorism. In some instances, book chapters were not included in our study if the majority of the information was included in another article or book. In total, 60 publications were ultimately reviewed for this study. These studies are listed in the Appendix.

After these publications were identified, we reviewed and detail-coded them for several attributes into a main database. While one researcher served as the primary coder for all 60 of the studies reviewed, two additional coders randomly selected a subsample of publications to review and verify variable-specific coding values, and procedures. By engaging in this iterative process, we are confident that our data are valid and reliable.

For each publication, several author and publication attributes are captured. First, a series of author-specific measures, including the disciplines of lead authors (or first authors listed), coauthoring patterns (single or multiple), and whether there are multiple publications by the same author, are examined. Second, we coded for several publication-specific measures, including year of publication, outlet type (book, journal article, chapter, MA thesis, or PhD dissertation), discipline of publication outlet (criminal justice, sociology, psychology, etc.), type of publication (theoretical, critical essay, quantitative, qualitative, or mixed-method), data source (open-source, official, or survey), method (descriptive or multivariate), primary country of conflict mentioned, and primary terrorist movement (far-right, global jihadi, local jihadi, left-wing/separatist, or ecoterrorism) mentioned. We also noted whether or not the study empirically tested Clarke and Newman’s EVIL DONE, MURDEROUS, and ESEER frameworks and tools claims.

Findings

In this section, we outline findings from our systematic review of studies published on the topic of SCP and terrorism. We begin by providing background information on the researchers who authored each of the studies, including their disciplinary backgrounds and patterns of coauthoring. Results from Table 2 indicate that the majority of SCP and terrorism studies are written by criminologists. In fact, criminal justice is considered to be the disciplinary background of the lead author in 50% of all reviewed studies. Psychology (17%) and sociology (10%) are the next most common disciplinary backgrounds of lead authors.

Table 2.

Lead Author’s Disciplinary Background.

	Frequency	%
Criminal Justice	30	50.0
Psychology	10	16.7
Sociology	6	10.0
Political Science	4	6.7
Anthropology	2	3.3
Engineering	2	3.3
Chemistry	1	1.7
Military Studies	1	1.7
Public Affairs	1	1.7
Religious Studies	1	1.7
Security Studies	1	1.7
Social Work	1	1.7
Total	60	100

Whereas prior research has found that most terrorism researchers overall have political science as their disciplinary background (Silke, 2004), we find that only four (7%) of the studies reviewed on SCP and terrorism are authored by political scientists. In short, most academics applying SCP to terrorism are criminologists, while this perspective has been adopted only sparingly by other social scientists studying terrorism.

In his review of general terrorism research, Silke (2004) found that terrorism studies were rarely carried out by teams of researchers. In fact, over 90% of published terrorism studies were solo authored during the 1990s. He described this pattern in part as a consequence of limited resources available for conducting terrorism research and suggested that the field was largely dependent on the work of a small number of isolated researchers.

In contrast, our findings outlined in Table 3 reveal that since 2006 around half of terrorism studies applying SCP to terrorism have been authored by teams of researchers. This finding aligns with prior research which has found that collaborative scholarly work has increasingly become the norm among criminologists rather than the exception (Fisher, Vander Ven, Cobane, Cullen, & Wiliams, 1998).

Table 3.

Number of Authors.

	Frequency	%
Single-authored works	31	51.7
Multiple-authored works	29	48.3
Total	60	100

Silke (2004) also found that over 80% of terrorism studies published during the 1990s was written by “one-time” authors. Merari (1991) viewed this trend as problematic, suggesting that the transient nature in terrorism studies’ authorship made it difficult to establish a solid conceptual framework based on sustained scholarship by scholars who have built upon their prior studies to cumulatively make a large impact in this area of research. In this way, findings from the current study support prior terrorism research.

Table 4 demonstrates that only 10 (17%) of the studies included in our review are written by a lead author who is also a lead author on one or more additional study examining SCP and terrorism. This suggests that there are few researchers who have made studying terrorism from a SCP perspective a mainstay of their research agendas. The most prolific lead author on the topic of SCP and terrorism is Graeme Newman, coauthor of the Clarke and Newman (2006) study that set the agenda for applying SCP to the study of terrorism. Newman is responsible for authoring four (7%) of the studies included in the current review. The only other author to be the lead author on more than two studies is Sunniva Frishlid Meyer, who authored three studies related to her doctoral dissertation research. All other studies included in our review are authored by duos or single authors (83%).

Table 4.

Publication of Multiple Works as Lead Author.

	Frequency	%
Single lead authored works	50	83.3
Multiple lead authored works	10	16.7
Total	60	100

Publication Attributes

Our findings outlined in Table 5 reveal that of the 60 studies included in our review 40 are peer-reviewed articles (68%), 11 are book chapters (18%), four are books (7%), three are master’s theses (5%), and two are doctoral dissertations (3%).¹ These findings suggest that this growing area of research is advancing knowledge about SCP and terrorism in large part through the peer-review processes.

Table 5.

Type of Outlet.

	Frequency	%
Peer-reviewed journal article	40	66.7
Book chapter	11	18.3
Book	4	6.7
Master’s thesis	3	5.0
Doctoral dissertation	2	3.3
Total	60	100

As expected, the number of studies applying tenets of SCP to terrorism increased after the publication of Clarke and Newman’s (2006) seminal work, although there has not been a precipitous increase of relevant studies over time. Instead, Table 6 indicates that the number of publications in this area peaked in 2009 due in large part to a special issue volume of Crime Prevention Studies focusing specifically on this topic (Freilich & Newman, 2009).

Table 6.

Year of Publication.

Year	Frequency	%
2006	1	1.7
2007	4	6.7
2008	3	5.0
2009	11	18.3
2010	3	5.0
2011	6	10.0
2012	10	16.7
2013	6	10.0
2014	3	5.0
2015	9	15.0
2016	4	6.7
Total	60	100

The number of relevant studies also increased in 2012 and includes chapters from Lum and Kennedy’s (2012) book titled Evidence-based Counterterrorism Policy, as well as a series of chapters from Taylor and Currie’s (2012) edited volume titled Terrorism and Affordance. The 2015 peak in SCP and terrorism studies is due to an array of articles appearing in both terrorism and criminal justice journals.

Table 7 demonstrates that the majority (67%) of SCP and terrorism studies published in peer-reviewed journals are published in outlets categorized as criminology and criminal justice journals. The placements of these studies include top-ranked American journals (e.g., Justice Quarterly [JQ], Criminology & Public Policy [CPP], Journal of Quantitative Criminology [JQC]) and international journals, such as European Journal on Criminal Policy & Research.

Table 7.

Types of Peer-Reviewed Journal Outlets.

	Frequency	%
Criminology/criminal justice	27	67.5
Security	5	12.5
Terrorism	6	15.0
Public affairs	2	5.0
Total	40	100

Note. Only studies published in peer-reviewed journals considered.

The next most common category of scholarly journal outlet includes security journals, such as Security Journal and Crime Prevention and Community Safety. The leading terrorism journal Terrorism and Political Violence is the most represented journal in this category, while relevant studies are also published in journals that include Studies in Conflict and Terrorism and Behavioral Sciences of Terrorism and Political Aggression.

Analytical Attributes

Examining the methodological and analytical features of these studies, Table 8 indicates that most are categorized as theoretical works centering on SCP and terrorism and are absent empirical application. Approximately 7% of the studies are categorized as critical essays or reviews.

Table 8.

Type of Publication.

	Frequency	%
Theoretical	29	48.3
Quantitative	17	28.3
Qualitative	9	15.0
Critical essay or review	4	6.7
Mixed-method	1	1.7
Total	60	100

What this means is that well over half of all studies reviewed are not based on empirical observation. Of the remaining SCP and terrorism studies considered, 28% (n = 17) approach the study of terrorism quantitatively and 15% (n = 9) are qualitative analyses. Only a single study was assessed to consist of a mixed-method design, combining qualitative and quantitative methods.

Of those studies considered as empirical in nature (n = 27), Table 9 illustrates that approximately 70% rely on open-source terrorism databases. Since 9/11, government agencies such as the Department of Homeland Security and Department of Justice have dramatically increased funding for building and maintaining databases that systematically collect, code, and analyze data on terrorism events from publicly available sources (e.g., court documents, media reports).

Table 9.

Primary Type of Data Used in Empirical Studies.

	%	Valid %
Open-source data	19	70.4
Official data	7	25.9
Survey data	1	3.7
Total	27	100

Note. Only quantitative, qualitative, and mixed-method studies considered.

Today, three of the leading open-source terrorism databases containing information on the criminal activities of terrorism and extremist offenders, victims, and incidents are the American Terrorism Study (Smith, 1994), U.S. Extremist Crime Database (Freilich, Chermak, Belli, Gruenewald, & Parkin, 2014) and the Global Terrorism Database (LaFree & Dugan, 2007). Each of these databases were created by American criminologists in part because commonly relied upon crime data sources, such as the Federal Bureau of Investigation’s (FBI) Uniform Crime Reports, do not provide details on ideologically motivated crimes (Dugan & Distler, 2016; Freilich & LaFree, 2016). Although some studies rely on official data from foreign police agencies (e.g., Turkish National Police) and publicly accessible military sources, our findings demonstrate the challenges of relying on official data to study terrorism in the United States and the promise of open-source databases for advancing terrorism research.

By relying primarily on open-source databases, some criminologists have moved beyond simply summarizing and organizing terrorism data to making inferences about the situated nature of terrorism. Table 10 shows that of the quantitative studies that we examined (n = 17), seven offer descriptive statistics, while 10 employ more advanced inferential statistics.

Table 10.

Types of Statistical Approach Used.

	Frequency	%
Descriptive	7	41.2
Multivariate	10	58.8
Total	17	100

For context, Silke’s (2004) methodological review of terrorism studies found that quantitative terrorism studies published in the mid-1990s to late 1990s were rare, especially in comparison to studies published in related fields, such as criminology and forensic psychology. While quantitative SCP studies examining terrorism using inferential statistics still remain the exception, our findings indicate that criminologists are increasingly responsible for introducing advanced statistical methods to the study of terrorism prevention.

We also examine the geographic scope of the studies included in our review, finding that locations ranged considerably, and some (32%) did not focus on terrorism or terrorism prevention in any particular country. Nonetheless, it is possible to identify a primary country as the geographic focus in the remainder of the studies, and Table 11 demonstrates that the focus has largely been on Western countries, especially the United States (33%) and the United Kingdom (8%).

Table 11.

Primary Country of Conflict Discussed in Study.

	Frequency	%
United States	20	33.3
No primary country	19	31.7
United Kingdom	5	8.3
Iraq	3	5.0
Northern Ireland	3	5.0
Australia	2	3.3
Netherlands	2	3.3
Turkey	2	3.3
Afghanistan	1	1.7
Canada	1	1.7
Israel	1	1.6
Japan	1	1.6
Total	60	100

As for which terrorist movements were the primary focus of the studies, Table 12 reveals that nearly half (48%) of the studies in our systematic review focused on political violence more generally rather than narrowly on any single particular ideological movement. This is an interesting finding as it may be useful to apply SCP interventions to particular types of movements. Certain movements may face different opportunity structures than other movements (due to varying government and other responses), and may also favor certain crime types over others (due to varying access to weapons types, resources, and tools, etc.). For studies where a particular ideological movement was ascertainable, most have focused on terrorism perpetrated by those adhering to the global jihad movement (n = 19, 32%).

Table 12.

Primary Terrorist Movement Discussed.

	Frequency	%
No primary movement	29	48.3
Global jihad	19	31.7
Far-right	4	6.7
Local Jihad	3	5.0
Left-Wing Separatist	3	5.0
Ecoterrorism	2	3.3
Total	60	100

Despite far-right extremist violence being a more frequent occurrence in the United States (Parkin, Gruenewald, Klein, Chermak, & Freilich, 2017), and a top concern of American law enforcement (Carter, Chermak, Carter, & Drew, 2014), less than 7% (n = 4) of studies focused primarily on far-right extremist crimes, while even fewer focused on other terrorist movements (e.g., ecoterrorism).

Finally, although Clarke and Newman (2006) argued that terrorists usually rely on tools to carry out their attacks, and also crafted thoughtful assessment templates for identifying the targets most at risk for terrorist attacks, the weapons most useful to terrorists, and the types of conditions most likely to foster political violence, academics have generally failed to respond by subjecting these claims to empirical evaluation. Table 13 indicates that only five of the studies empirically tested EVIL DONE and, surprisingly, no studies empirically examined their tools claims. In addition, there have been no empirical tests of ESEER and just one of MURDEROUS.

Table 13.

Empirical Tests of EVIL DONE, MURDEROUS, and ESEER.

	Frequency	%
Tests EVIL DONE	5	8.2
Tests MURDEROUS	1	0.0
Tests ESEER	0	0.0
Tests tools claims	0	0.0

Discussion

Our findings point to a number of viable avenues for scholars to investigate and further the application of SCP to terrorism. In particular, we found that SCP and terrorism researchers are increasingly acting in ways that foster more sophisticated studies and research agendas. Almost half of the SCP and terrorism studies were collaborative efforts. This suggests that increased government funding from U.S. federal agencies, including the Departments of Defense, Justice and Homeland Security, and the National Science Foundation, among others, as well as support from other governments and international agencies are having an impact. Much of this funding has supported large-scale research projects, highlighting the benefits that diverse research teams, as opposed to solitary scholars, can produce (Silke, 2004). In addition, 17% of the studies were written by a lead author who was also a lead author on a second SCP and terrorism study. Scholars authoring multiple studies are assumed to be able to conduct a sustained, evolving research agenda that builds on prior works (Merari, 1991). This number would be higher if we included not just the lead author but the second and third authors as well. In addition, in 2017, which is beyond the time frame of our study, certain scholars (such as Hsu and Mandala) were lead authors on multiple SCP and terrorism articles. Further, these more sophisticated research teams seem to have produced higher quality research products. Over two thirds of the SCP and terrorism works were published as peer-reviewed articles, while an additional 7% were books. Only 18% of these works were published as book chapters. While there is still room for improvement, it appears that SCP and terrorism scholars are in some ways moving beyond the criticisms leveled against prior terrorism research (Silke, 2001, 2004).

Almost two thirds of the 40 journal articles were published in criminal justice outlets and included high-profile journals, such as the JQC, Crime & Delinquency (CAD), CPP, and JQ. These high-impact criminal justice and policy focused journals are a good match for SCP’s practical prevention based approach. Almost 15% of the articles were published in terrorism studies journals, including the leading terrorism journals Terrorism and Political Violence and Studies in Conflict and Terrorism. Another 13% of articles were published in security journals. While it is encouraging that SCP and terrorism researchers are also targeting terrorism studies and security journals, their work has not yet penetrated political science, sociology, or psychology journals. While political science and sociology have tended to concentrate on grievances and other distal factors (Perry & Hasisi, 2015), it is surprising that few SCP and terrorism studies have been published in psychology journals. Clarke, SCP’s founder, is a trained psychologist and a number of SCP’s 25 prevention techniques are based upon social psychological principles (Wortley, 2002).

Half of all the scholars relying upon SCP to study terrorism were trained in criminology and criminal justice. Considering that SCP is a subfield of criminal justice, this is not surprising. In a sense, we have also undercounted the criminal justice influence as certain authors, such as Clarke and Newman themselves, although trained in other disciplines (such as psychology and sociology) have devoted most of their careers to studying criminal justice issues. In addition, over half of the studies were authored by noncriminologists. Thus, it appears that the SCP approach to terrorism is gradually entering other fields.

Turning to the two disciplines that have historically dominated the study of terrorism, it is not surprising that psychologists (17%) were almost three times as likely as political scientists (7%) to author these studies. Again, SCP has long been informed by social psychology and other psychological fields (Wortley, 2002). Political science’s focus on grievances and other distal factors may make it less open to situational approaches. It is intriguing that although psychologists are authoring SCP and terrorism studies few of their articles have been published in psychology journals. SCP and terrorism scholars should aim to address this gap in the future. Publishing such works in psychology and even political science journals would expose SCP principles and their utility in reducing terrorism to new audiences. These studies could also possibly inspire novel SCP and terrorism research agendas and collaborations across disciplines.

It is also interesting that although Clarke and Newman’s work is still relatively recent in academic terms, it has already resulted in five MA and PhD theses. This number is actually undercounted because many MA and PhD theses do not appear in the search engines we relied upon, and as noted we excluded graduate theses (such as Hsu’s) if a substantial portion of the content was replicated in other articles included in our analysis. In addition, some SCP and terrorism related dissertations were published subsequent to this study’s time period, and other relevant MA theses and PhD dissertations are in progress. As, as we outline below, important SCP claims and terrorism issues remain unresolved, there remain ample opportunities for further graduate dissertations/theses in this area.

Our analyses also revealed that since 2007 there have been at least three works on SCP and terrorism published every year, with some years producing much more than that. Importantly, the 2015 peak in SCP and terrorism studies (n = 9) is less related to the publication of special issues and instead is constituted by an array of relevant scholarly studies published in both terrorism and criminal justice journals. In the period subsequent to our study’s time period, at least nine additional works (see for example, Hsu & McDowall, 2017; Hsu, Vasquez, & McDowall, 2018; Lasley & Guffey, 2017; Mandala, 2017; Mandala & Freilich, 2017, 2018; Romyn & Kebbell, 2018; St. George, 2017; Yang & Jen, 2017) were published using SCP to study terrorism. These works included two PhD dissertations and seven articles, some of which appeared in top tier journals such CAD, JQ, and the Journal of Research in Crime and Delinquency.

Around 55% of the studies we reviewed were unempirical theoretical or critical reviews. Many qualitative works consist of case studies using Cornish’s (1994) script method. This approach breaks criminal acts down to the sequential steps necessary to successfully carry the crime out. The script method is useful in identifying the opportunities that the offenders took advantage of so that prevention policies can be devised to thwart these offenses in the future. But, these case studies do not actually evaluate the effectiveness of the suggested interventions. Only 28% and 2% of studies, respectively, relied upon quantitative or mixed research methods. Of these studies, 40% were descriptive while only 10 studies used multivariate analyses. While quantitative SCP studies are not the norm, our findings reveal that SCP and terrorism researchers have begun to use advanced statistical methods. Future research should increase its use of such methods and include comparison groups to test SCP claims and frameworks, as Ekici, Ozkan, Celik, and Maxfield (2008) first suggested.

As for sources of data utilized, over 70% of the empirical SCP and terrorism studies relied upon open-source data, usually large-scale databases. Importantly, scholars did not limit themselves to only one database with the studies in our sample relying on the American Terrorism Study, the Global Terrorism Database, and the Extremist Crime Database. In addition, over 25% of the SCP and terrorism studies used official data, including data from the Turkish police, the U.S. Military in Iraq, and the Israeli government. Sullivan and McGloin (2014) have cautioned criminology to pay attention to measurement issues, noting that the field’s many delinquency studies have also relied on a small number of data sources. It is thus encouraging to see such an array of databases and government data being used to investigate the SCP framework in the terrorism context. As almost three times as many of the data-driven studies used open sources as opposed to official data, our findings again demonstrate that the increased government funding for research on the creation and maintenance of these databases is indeed proving useful to terrorism researchers.

Our results also highlight that, with certain exceptions, it remains difficult for academics to access official data to study terrorism in the United States and many other locations. Going forward, SCP researchers need to think creatively about strategies to gain the cooperation of official agencies to access to their terrorism data. Police data, for instance, have proved incredibly useful to criminologists examining topics that include delinquency and gangs, and such studies have shown that social network analysis (SNA) and other methods have much to offer criminology (Bichler & Malm, 2015). SCP proponents have also long relied upon SNA in their prevention efforts of crime overall. Thus, increased access to official data could allow SCP scholars to increasingly use SNA to devise more effective strategies to prevent terrorism (Bichler & Malm, 2015).

Turning to the geographic scope of the studies, we found that the locations of terrorism examined greatly varied. While over 30% of studies did not focus on a specific nation, almost 70% of studies did. While the studies have been partial to the West, other nations and regions were also examined. Studies that we reviewed looked at Israel/West Bank, Turkey, Afghanistan, and Iraq, among others. Intriguingly, in terms of the terrorist movement examined, we found that almost half of the studies highlighted political violence overall, and did not study a specific terrorist or extremist movement. Again, this is interesting as SCP stresses the need to investigate specific problems so that interventions can then be tailored to these narrow problems (Freilich & Newman, 2016). For studies where a there was a specific extremist ideological movement, most examined the global jihad movement (n = 19, 31%). Fewer studies examined the far-right, far-left, or ecoterrorists although these movements have also been active in the United States and elsewhere and have caused much death, destruction, and financial damage. However, the studies we reviewed did examine a variety of crime types, such as kidnappings and antipolice attacks (Freilich & Chermak, 2009; see also Mandala, 2017). In this sense scholars were engaging in SCP’s specificity requirement, although this only occurred in a minority of cases.

Next Steps for SCP and Terrorism Research

Our findings show that SCP could be a promising strategy for reducing and preventing terrorism. Thus far, we have mostly discussed the SCP and terrorism’s literature metadata, including the types of data and methods used, and publishing outlets, among others. We now engage this literature’s substantive content, including some of its key findings, gaps, and omission, and outline a number of important points that researchers should address to further this area of study.

To begin, we found that no studies subjected the ESEER template to an empirical examination. The ESEER template captures Clarke and Newman’s (2006) facilitating conditions, a pillar of SCP that has rarely been engaged (see Eck & Madensen, 2009, for an exception). This pillar’s innovation is its highlighting of social conditions and their situational implications for terrorist opportunities. Clarke and Newman, for example, discuss immigration in this way, and illustrate how terrorists make use of immigrant communities as they plan their attacks to successfully complete their strikes. Wortley (1996) and Freilich and Chermak (2009) have similarly outlined the situational implications of factors like guilt and ideology usually thought to be more distal attributes. A situational focus on guilt would consider relevant cues present during certain events, for instance, and how they play upon a potential offender’s loyalty to their friends to ensure their conformity. Conversely, a more distal etiological model would likely suggest that guilt originating from childhood conflicts with one’s parents (such as a Freudian argument) could increase that person’s propensity for offending in all situations.

There was only a single study (Legault & Hendrickson, 2009) that tested the MURDEROUS framework during the time frame we examined, although Mandala and Freilich (2018) subsequently did so in their study that compared successful and unsuccessful terrorist assassinations. Mandala and Freilich (2018) found that successful assassinations are more likely to occur when terrorists use firearms instead of explosives. This result may support Clarke and Newman’s (2006) MURDEROUS template which claims terrorists are more likely to employ familiar, easy-to-access and simple-to-use weapons like guns.

Similarly, no scholars have examined Clarke and Newman’s pillar of tools used to commit terrorism, although Mandala (2017) recently did so in her doctoral dissertation. Clarke and Newman argue that tools, such as money (that could be used to acquire weapons) or official documents (that make it easier to travel without being noticed by the authorities) provide important benefits to terrorists. Thus, terrorists who use these tools are more likely to succeed than terrorists who do not have access to these tools. Mandala (2017) found that successful terrorist assassinations were more likely to occur when the terrorists used a motorcycle (tool) compared to attacks occurring outside a building or structure where no tools were used.

The small number of studies empirically investigating the four pillars of terrorism opportunity initially appears surprising. Clarke and Newman’s EVIL DONE, MURDEROUS, and ESEER frameworks, as well as tools arguments, lend themselves to hypotheses about target selection, weapon use, tools used, and social conditions. The most tested of Clarke and Newman’s four pillars of terrorist opportunity was the EVIL DONE framework, a risk assessment tool designed to identify the targets most vulnerable to a terrorist attack. Interestingly, although EVIL DONE attracted the most attention there still only were five studies that empirically examined this pillar.

Future research should seek to increase the use of sophisticated methods to test these pillars of opportunity. One reason for the small number of empirical tests of EVIL DONE and the other pillars may be the difficulty of accessing the type of data necessary to conduct complete tests of relevant hypotheses. For example, one strategy to evaluate EVIL DONE would be to compare targets that terrorists attacked to similar targets that have not been attacked, or cases where the attackers were foiled, by using a case-control design to determine if the attacked and nonattacked targets differed on EVIL DONE’s dimensions (Clarke & Eck, 2005; Loftin & McDowall, 1988). The case-control method has rarely been used in terrorism research and it has never been applied to SCP claims. Although it appears to be a promising strategy to examine such questions, it would require crafting a careful design. To pursue this type of study in the terrorism context scholars would have to define similar nonattacked targets and outline a strategy for identifying and selecting them.

It is perhaps due to the difficulty of obtaining data for matched nonattacked targets that scholars have sought to extend Clarke and Newman’s claims and then tested these hypotheses with easier to access data. For example, St. George’s (2017) doctoral dissertation recently used the EVIL DONE framework to account for varying fatalities and injuries across attacked targets. This strategy did not require identifying and collecting data on nonattacked targets. Instead, it only necessitated scoring all attacked targets on EVIL DONE’s dimensions, the number of deaths and injuries from each attack, and then investigating if targets scoring higher on EVIL DONE (i.e., more vulnerable) suffer more deaths and injuries.

In a somewhat similar vein, two of the authors here (with colleagues) are working on a study using SCP devised claims to account for weapon use variation across suicide and nonsuicide attacks in the United States. We did so partially because of the availability of these data, as opposed to comparing weapon use across suicide attacks and nonattacked targets as it would be difficult to identify matched nonattacked targets. Mandala and Freilich (2017), as noted, also tested MURDEROUS by examining whether simple and easy-to-use weapons like guns, as opposed to explosives, are more likely to be associated with a successful terrorist attack (i.e., assassination). Data for these attributes are readily available. Mandala and Freilich’s test extended Clarke and Newman’s MURDEOUS template that was initially constructed to account for the type of weapons terrorists use during all attacks (both successful and failed; see Legault & Hendrickson, 2009) as opposed to accounting for varying weapon use across the success or failure of attacks.

Turning to the content of the EVIL DONE template, Ekici et al (2008) suggest that researchers, law enforcement analysts, and counterterrorism officials collaborate to refine the application of its dimensions. Romyn and Kebbell (2018, p. 591) argue that one problem with the EVIL DONE approach is that it assumes that all attributes are equally important . . . [but they previously found] that the attributes of Occupied, Iconic, Easy and Destructible were the most important when selecting a target, while the attributes Exposed, Vital and Near were less important . . . [and] Legitimate was extremely subjective.

It is important for future research to continue this line of research. If these differences across attributes hold, perhaps the EVIL DONE template needs to be refined by increasingly weighting the more important attributes.

Future research should also extend Boba’s (2008, 2009); work conceptualizing EVIL DONE that added the expected loss from the attack into the framework. For example, also adding ideology as a dimension to EVIL DONE could improve its assessment of vulnerable targets. While far-rightists and jihadists have both often sought to purposefully kill their enemies and maximize fatalities and injuries, environmental and animal rights extremists have tried to prevent deaths in their strikes; instead, aiming for large amounts of property damage. EVIL DONE’s occupied dimension would seem to work in opposite ways dependent upon ideological movement, with far-rightists and jihadists finding a target occupied with their enemies as more attractive, and ecoextremists viewing such targets as less attractive.

In addition, terrorism researchers have long noted that ideology often plays a role in target selection (Drake, 1998). Jihadists in the United States are more likely to single-out Jews, gays, and American society overall, far-rightists are more likely to target the government, especially the police, racial/ethnic/religious minorities, and gays, while far-leftists are more likely to strike corporations and animal testing laboratories. In all of these cases, movement-specific ideologies indicate potential targets. Further, as discussed, ideology may also have situational implications where the target’s design and markings could affect how it is perceived by potential attackers. This in turn could situationally increase motivation to attack (Freilich & Chermak, 2009). An offender’s extremist ideology, in other words, could affect how that offender views a potential target, whether or not their motivation to attack situationally increases or decreases (due to cues from the target), and how they situationally construct and interpret opportunities (Wortley, 2002). In short, accounting for ideology situationally (as opposed to distally) in the EVIL DONE template may enhance its usefulness.

Finally, we end by discussing the common critique leveled against SCP in the criminology literature, specifically that prevention interventions will not reduce crime but will instead displace it elsewhere in terms of geography, time, target selection, tactics, offenders, or crime types (Reppetto, 1976). Terrorism scholars have made similar arguments and referred to displacement as the substitution effect. Hsu and his colleagues have extensively investigated this issue and, similar to the criminology literature (Guerette & Bowers, 2009), have found that displacement is not a given and that there is in fact sometimes a diffusion of benefits effect. Hsu and Apel (2015), one of the studies we reviewed, used data from the Global Terrorism Database to examine displacement among terrorist groups that had attacked aviation targets both before and after airport metal detectors were installed. Hsu and Apel used an interrupted time series design and found partial support of SCP claims.

Subsequently, in the period beyond our study’s time frame, Hsu and colleagues (Hsu & McDowall, 2017; Hsu et al., 2018) published two additional studies. One study empirically investigated the assumption that once a prime-target country increases the price of attacks, terrorists will shift their attention to prime-targets overseas. Hsu and colleagues found that there was no displacement to targets abroad and instead found some evidence for a diffusion of benefits in which attacks against U.S. targets abroad decreased after 9/11. The second study explored whether the common counterterrorism strategy of target hardening engenders greater amounts of casualty attacks against protected targets. Some have expressed concern that the increased cost, effort, and risk of attacking a protected target will result in more deadly attacks against the hardened target as terrorists use more forceful means to overcome security measures to successfully strike the target. Hsu and colleagues found that the frequency and proportion of casualty attacks against aviation targets and U.S. diplomatic targets did not increase (in both the immediate and long term) following target hardening efforts.

It is encouraging that following an SCP counterterrorism intervention displacement often does not occur and there is sometimes a diffusion of benefits effect. Clarke and Newman (2006), however, caution that certain terrorists committed to their cause will “adapt,” and eventually may employ innovative strategies to surmount successful interventions. This highlights an important yet understudied issue for SCP and crime overall—the relationship between displacement and adaptation. Displacement is portrayed as a short-term effect, while adaptation is seen as a process occurring over an extended period of time. When a terrorist group’s reaction to an SCP intervention is classified as adaptation as opposed to displacement is still unclear. Conceptually, this is an important issue as any displacement occurring would undermine SCP’s claims, while adaptation would not, and in fact would be expected. As adaptation may be more expected in the terrorism context, this is a key issue for future research to unpack.

Conclusion

As with criminology overall, SCP has much to contribute to both the academic study of terrorism and efforts to safeguard societies from terrorist threats. In this study, we systematically reviewed the first 10 years of the SCP and terrorism literature to describe the state of this research. We found a strong SCP and terrorism literature. We also identified a number of underexplored issues that deserve more attention, such as the need for more multivariate designs, focus more on specific terrorist movements and the strategies employed against them, and possibly refine EVIL DONE and the other pillars of terrorist opportunity. Relatedly, we also highlighted the importance of conducting rigorous evaluations and using additional data sources to conduct more complete empirical tests of SCP’s EVIL DONE, MURDEROUS, and ESEER frameworks and tools claims. We set forth specific strategies that might prove helpful in this regard. It is our hope that future research continues to investigate and extend applications of SCP to the terrorism context.

Footnotes

Appendix

List of Publications Reviewed.

1	Belli, R., & J. D. Freilich. (2009). Situational crime prevention and non-violent terrorism: A “soft” approach against ideologically motivated tax refusal. Crime Prevention Studies, 25, 173-206.
2	Bjørgo, T. (2013). Strategies for preventing terrorism. New York, NY: Springer.
3	Bjørgo, T. (2016). Counter-terrorism as crime prevention: A holistic approach. Behavioral Sciences of Terrorism and Political Aggression, 8, 25-44.
4	Block, M. M. (2016). Applying situational crime prevention to terrorism against airports and aircrafts (Doctoral dissertation). University of Louisville, Kentucky.
5	Boba, R. (2009). EVIL DONE. Crime Prevention Studies, 25, 71-91.
6	Borrion, H., Tripathi, K., Chen, P., & Moon, S. (2014). Threat detection: A framework for security architects and designers of metropolitan rail systems. Urban, Planning & Transport Research, 2, 173-194.
7	Braithwaite, A., & Johnson, S. D. (2015). The battle for Baghdad: Testing hypotheses about insurgency from risk heterogeneity, repeat victimization, and denial policing approaches. Terrorism and Political Violence, 27, 112-132.
8	Cave, B. (2012). Counterinsurgency and criminology. Applying routine activities theory to military approaches to counterterrorism. In C. Lum & L. W. Kennedy (Eds.), Evidence-based counterterrorism policy (pp. 323-349). New York, NY: Springer
9	Clare, J. & F. Morgan. (2009). Exploring parallels between Situational Crime Prevention and non-criminological theories for reducing terrorist risk. Crime Prevention Studies, 25, 207- 228.
10	Clark, W. (2009). Bioterrorism: A situational crime prevention approach. Crime Prevention Studies, 25, 93-110.
11	Clarke, R.V. & Newman, G. R. (2006). Outsmarting the terrorists. New York, NY: Praeger.
12	Clarke, R. V., & Newman, G. R. (2007). Police and the prevention of terrorism. Policing, 1(1), 9-20.
13	Currie, P.M. (2012). Affordance as an inferred oportunity. In M. Taylor & P. M. Currie (Eds.), Terrorism and affordance (pp. 157-170). New York, NY: Continuum International Publishing Group.
14	De Bie, J. L., de Poot, C. J., & van der Leun, J. P. (2015). Shifting modus operandi of Jihadist foreign fighters from the Netherlands between 2000 and 2013: A crime script analysis. Terrorism and Political Violence, 27, 416-440.
15	Donkin, S. (2014). Preventing terrorism and controlling risk: A comparative analysis of control orders in the UK and Australia. New York, NY: Springer.
16	Duguay, R. (2015). Threats of radiological terrorism and the securing of radioactive sources. Journal Of Physical Security, 8, 55-68.
17	Ekblom, P., & Hirschfield, A. (2014). Developing an alternative formulation of SCP principles–the Ds (11 and counting). Crime Science, 3, 1-11.
18	Ekblom, P. (2012). Conceptual and methodological explorations in affordance and counter terrorism. In M. Taylor & P.M. Currie (Eds.), Terrorism and affordance (pp. 33-48). New York, NY: Continuum International Publishing Group.
19	Ekici, N., Ozkan, M., Celik, A., & Maxfield, M. G. (2008). Outsmarting terrorists in Turkey. Crime Prevention & Community Safety, 10, 126-139.
20	Fahey, S., LaFree, G., Dugan, L., & Piquero, A. R. (2012). A situational model for distinguishing terrorist and non-terrorist aerial hijackings, 1948–2007. Justice Quarterly, 29, 573-595.
21	Freilich, J. D. & S. M. Chermak. (2009). Preventing deadly encounters between law enforcement and American far-rightists. Crime Prevention Studies, 25, 141-172.
22	Fussey, P. (2007). Observing potentiality in the global city surveillance and counterterrorism in London. International Criminal Justice Review, 17, 171-192.
23	Fussey, P. (2011). An economy of choice? Terrorist decision-making and criminological rational choice theories reconsidered. Security Journal, 24, 85-99.
24	Gibbs, S. (2010). Applying the theory and techniques of situational criminology to counterinsurgency operations: reducing insurgency through situational prevention (Doctoral dissertation). Naval Postgraduate School, Monterey, CA.
25	Greene, J. R. (2009). Weapon choice and American political violence. Criminology & Public Policy, 8, 647-654.
26	Gruenewald, J., Allison-Gruenewald, K., & Klein, B. R. (2015). Assessing the attractiveness and vulnerability of eco-terrorism targets: A situational crime prevention approach. Studies in Conflict & Terrorism.
27	Hsu, H. Y. (2013). Post-9/11 U.S. airport security changes and displacement. In S. G. Shoham & J. D. Freilich (Eds.), Policing & preventing terrorism around the globe. Ontario, Canada: de Sitter.
28	Hsu, H. Y., & Apel, R. (2015). A situational model of displacement and diffusion following the introduction of airport metal detectors. Terrorism and Political Violence, 27, 29-52.
29	Johnson, S. D. & Braithwaite, A. (2009). Spatio-temporal modeling of insurgency in Iraq. Crime Prevention Studies, 25, 9-32.
30	Jones, M. (2011). Can railway station design reduce the risk of a terrorist attack or the impact of an incident? Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, 225, 351-357.
31	Klein, B. R., Gruenewald, J., & Smith, B. L. (2016). Opportunity, group structure, temporal patterns, and successful outcomes of far-right terrorism Incidents in the United States. Crime & Delinquency, 1-26.
32	Legault, R. L., & Hendrickson, J. C. (2009). Weapon choice and American political violence: A comparison of terrorists in federal custody to other felons. Criminology & Public Policy, 8, 531-559.
33	Lulham, R., O. C. Duarte, K. Dorst & L. Kaldor. (2012). Designing a counterterrorism trash bin. Crime Prevention Studies, 27, 131-146.
34	Lum, C. & Koper, C. (2011). Is crime prevention relevant to counterterrorism? In B. Forst, J. R. Greene, & J. P. Lynch (Eds.), Criminologists on terrorism and homeland security (pp. 129-150). New York, NY: Cambridge University Press.
35	Lum, C., Gill, C., Cave, B., Hibdon, J., & Weisburd, D. (2012). Translational criminology: Using existing evidence for assessing TSA’s comprehensive security strategy at airports. In C. Lum & L. W. Kennedy (Eds.), Evidence-based counterterrorism policy (pp. 209-251). New York, NY: Springer.
36	Lynch, J. P. (2011). Implications of opportunity theory for combatting terrorism. In B. Forst, J. R. Greene & J. P. Lynch (Eds.), Criminologists on terrorism and homeland security (pp. 151-181). New York, NY: Cambridge University Press.
37	Meyer, S., & Ekblom, P. (2012). Specifying the explosion-resistant railway carriage—A “bench” test of the Security Function Framework. Journal of Transportation Security, 5, 69-85.
38	Meyer, S. (2012). Reducing harm from explosive attacks against railways. Security Journal, 25, 309-325.
39	Meyer, S. (2013). Impeding lone-wolf attacks: lessons derived from the 2011 Norway attacks. Crime Science, 2(1), 1.
40	Morris, N. A. (2015). Target suitability and terrorism events at places. Criminology & Public Policy, 14, 417-426.
41	Newman, G. R., & Clarke, R. V. (2007). Commentary: The situational prevention of terrorism: Some ethical considerations. Criminal Justice Ethics, 26, 2-66.
42	Newman, G. R. & Clarke, R. V. (2010). Terrorism. In M. Natarajan (Ed.), International criminal justice. Cambridge, UK: Cambridge University Press.
43	Newman, G. R. (2009). Reducing terrorist opportunities: A framewok for foreign policy. Crime Prevention Studies, 25, 33-60.
44	Özer, M. M., & Akbaş, H. (2011). The application of situational crime prevention to terrorism. Turkish Journal of Police Studies, 13, 179-194.
45	Paton, S. (2013). EVIL DONE vulnerability assessment: Examining terrorist targets through situational crime prevention (Doctoral dissertation). Florida Atlantic University, Boca Raton.
46	Perry, S., & Hasisi, B. (2015). Rational choice rewards and the Jihadist suicide bomber. Terrorism and Political Violence, 27, 53-80.
47	Perry, S., Apel, R., Newman, G. R., & Clarke, R. V. 2017. The situational prevention of terrorism: An evaluation of the Israeli West Bank Barrier. Journal of Quantitative Criminology, 33, 727-751.
48	Prenzler, T. (2014). Re-thinking counter-terrorism and crime prevention strategies from a harm perspective. Australasian Policing, 6(2), 15.
49	Roach, J., Ekblom, P., & Flynn, R. (2005). The conjunction of terrorist opportunity: A framework for diagnosing and preventing acts of terrorism. Security Journal, 18(3), 7-25.
50	Roach, J. (2012). Affordance, terrorism and the overestimation of offender homogeneity. In M. Taylor & P. M. Currie (Eds.), Terrorism and affordance (pp. 141-156). New York, NY: Continuum International Publishing Group.
51	Romyn, D., & Kebbell, M. (2014). Terrorists’ planning of attacks: a simulated “red-team” investigation into decision-making. Psychology, Crime & Law, 20, 480-496.
52	Rorie, M. L. (2008). Communicating through violence: An application of rational choice theory to terrorist claims of responsibility (Master’s thesis). University of Maryland, College Park.
53	Ross, N. (2009). How to lose the war on terror: Lessons of a 30 year war in Northern Ireland. Crime Prevention Studies, 25, 229-244.
54	Safer-Lichtenstein, A. 2015. Incorporating ideas of displacement and diffusion of benefits into evaluations of counterterrorism policy (Doctoral dissertation). University of Maryland, College Park.
55	Shaftoe, H., Turksen, U., Lever, J., & Williams, S. J. (2007). Dealing with terrorist threats through a crime prevention and community safety approach. Crime Prevention & Community Safety, 9, 291-307.
56	Silke, A. (2010). Understanding terrorist target selection. In A. Richards, P. Fussey, & A. Silke (Eds.), Terrorism and the Olympics: Major event security and lessons for the future. (pp. 49-71). New York, NY: Routledge.
57	Townsley, M., Johnson, S. D., & Ratcliffe, J. H. (2008). Space time dynamics of insurgent activity in Iraq. Security Journal, 21, 139-146.
58	Weenink, A. W. (2012). Situational prevention of terrorism. Remarks from the field of counterterrorism in the Netherlands on Newman and Clarke’s Policing Terrorism. Trends in Organized Crime, 15, 164-179.
59	Wortley, R. (2012). Affordance and situational crime prevention: Implications for counter terrorism. In M. Taylor & P. M. Currie (Eds.), Terrorism and affordance (pp. 17-32). New York, NY: Continuum International Publishing Group.
60	Yun, M. (2009). Application of situational crime prevention to terrorist hostage taking and kidnapping: A case study of 23 Korean hostages in Afghanistan. Crime Prevention Studies, 25, 111-139

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

Notes

Author Biographies

Joshua D. Freilich is a member of the Criminal Justice Department at John Jay College. He is a Creator and coDirector of the U.S. Extremist Crime Database, a Creator and co-Director of the U.S. School Shooting Database, and the Chair (2017-19) of the American Society of Criminology’s Division on Terrorism and Bias Crimes.

Jeff Gruenewald is an associate professor in the School of Public and Environmental Affairs at Indiana UniversityPurdue University, Indianapolis. His research addresses issues of homicide, terrorism and bias crime, homeland security policy, and media representations of violence.

Marissa Mandala is a research analyst at the New York City Police Department’s Office of Management, Analysis & Planning. She graduated in 2018 with her PhD in criminal justice from John Jay College at the CUNY Graduate Center. She received her Master’s in criminology 18 Criminal Justice Policy Review from the University of Pennsylvania in 2013, and her BA in international relations and political science from the University of Southern California in 2009.

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