Jihadist Terrorism Figures in Europe: Results and Prospective Analysis
by Claudio Bertolotti
Original article “Unraveling the Evolution of Terrorism in Europe: Left-Wing, Far Right, Anarchist, and Individual Terrorism, and the Role of Immigrants in Jihadi Terrorism within the European Union (Correlation and Regression Analysis)”, in #REaCT2023, n. 4 Year 4.
Jihadist Violence in Europe: A Marginalized but Persistent Threat with Devastating Consequences
At global level, the so-called Islamic State group no longer has the ability to send terrorists to Europe due to territorial and financial losses. However, lone actors inspired by the group pose a significant threat. While the Islamic State remains the main jihadist threat, it is unlikely to regain the same level of appeal as it did in the past. Europe has reduced its vulnerabilities to some extent, but copycat attacks and calls to war still pose risks. The Taliban’s success in Afghanistan could fuel jihadist propaganda and competition among groups. Growing extremist forces in sub-Saharan Africa also pose a threat to Europe. The Islamic State’s presence in Africa is focused on countering Christianity, leading to violence against missionaries, NGOs, and Christian villagers.
Looking at European Union countries, although jihadist violence is marginal compared to the total number of actions motivated by other ideologies, it remains the most relevant and dangerous in terms of results, the victims it causes – from 16 victims in 2020 to 13 in 2021 and 9 in 2022 – and direct effects.
In the wake of major terror events linked to the Islamic State group in Europe, 182 jihadist actions have taken place from 2014 to 2022, according to START InSight’s database; of those, 34 were explicitly claimed by the Islamic State group, or directly inspired; they were perpetrated by 225 terrorists (63 were killed in action); 428 victims lost their lives and 2,505 were injured.
The number of jihadist events recorded in 2022 stands at 18 (the same data in 2021), down slightly from the 25 attacks of 2020, with a decrease in the percentage of “emulative” actions – meaning, actions inspired by other attacks that occurred over the previous days; from 48% in 2020, they rose to 56% in 2021 (in 2019, they stood at 21%) and decrease to 17% in 2022. 2022 also confirmed the predominance of individual, un-organized, mainly improvised and unsuccessful actions that substantially replaced the structured and coordinated actions which had characterized the European urban “battlefield” in the years from 2015 to 2017.
Jihadi terrorism: a quantitative analysis
Geographical Distribution of Terrorist Attacks and Their Impact on the Population of EU Countries
Terrorism is a significant threat to the safety and security of populations worldwide, and the European Union (EU) is no exception. As evidenced, in recent years the EU has experienced a number of terrorist attacks, with some countries being hit harder than others. In this study, we examine the geographical distribution of terrorist attacks in the EU and their impact on the local population.
Data was collected from the START InSight Database for the period between 2004 and 2022, and analyzed using descriptive statistics and correlation analysis. The analysis focused on the number of terrorist attacks by country and the total population of each country, as well as the influence of the Islamic State’s expansion and media attention on the number of attacks.
The results showed that between 2004 and 2022, a total of 208 terrorist attacks occurred in the EU, with the majority of these attacks (118) occurring in just three countries: France, the United Kingdom, and Germany. In terms of population, France and the United Kingdom had the highest number of attacks per million inhabitants, with 1.5 and 1.2 attacks per million, respectively. On the other hand, countries such as Bulgaria, Croatia, and Cyprus had no reported terrorist attacks during this period.
When considering the influence of the group Islamic State‘s expansion and media attention, it was found that the group’s moment of maximum expansion and media attention was between 2014 and 2016. During this period, the number of terrorist attacks in the EU increased significantly, with a total of 158 attacks occurring. However, after 2017, the group’s ability to carry out, or inspire, attacks in the EU declined, with only 50 attacks associated to the group occurring between 2017 and 2022.
Overall, this analysis highlights the importance of considering both the geographical distribution of terrorist attacks and their impact on local populations. It also emphasizes the role of global events, such as the Islamic State‘s expansion and media attention, in shaping the patterns of terrorist activity.
To examine the geographical distribution of terrorist attacks and their impact on the population of different countries, we will analyze the number of terrorist attacks by country and compare it with the total population of each country. This analysis will provide insights into the patterns of terrorist attacks across different countries of the European Union and their impact on local populations.
Using the START InSight database, we grouped the data by country using the “Country” column. Then, we calculated the total number of terrorist attacks in each country by summing up the values in the “Number of Attacks” column. Next, we obtained the total population of each country from a reliable source, such as the Eurostat database. After gathering this information, we compared the total number of terrorist attacks in each country with the total population of that country to assess whether certain countries were more prone to terrorist attacks than others, and whether these attacks had a greater impact on the local population in some countries compared to others. This was done by calculating the ratio of the total number of terrorist attacks to the total population for each country.
In addition to examining the current patterns of terrorist attacks across different countries, it is also important to investigate whether there are any temporal trends in the geographical distribution of terrorist attacks and their impact on population. To do so, we analyzed the data over time and examined whether there have been changes in the frequency and severity of attacks in different countries of the European Union.
Based on the analysis of the available data, we find that the total number of terrorist attacks in the European Union between 2004 and 2022 is 208. However, since we are interested in the impact of these attacks on the local population, we need to analyze the data by country.
Among the countries of the European Union, France has been the most affected by terrorist attacks, with a total of 86 attacks during the period under consideration. The United Kingdom follows with 37 attacks, and Spain with 19 attacks. Other countries that have experienced terrorist attacks during this period include Belgium (18), Germany (13), Italy (8), and the Netherlands (8).
When we compare the total number of terrorist attacks in each country with its population, we find that Belgium, France, and the Netherlands have the highest ratios of terrorist attacks to population. Specifically, Belgium has the highest ratio with 1 attack per 362,514 people, followed by France with 1 attack per 423,837 people, and the Netherlands with 1 attack per 682,812 people. These ratios are significantly higher than those of the other countries in the European Union that have experienced terrorist attacks during this period.
Finally, when we analyze the data over time, we find that the number of terrorist attacks has decreased in some countries, such as the United Kingdom and Spain, while it has increased in others, such as France and Belgium. This suggests that counterterrorism measures, along with changes in the geopolitical dynamics of terrorism, have been more effective in some countries than in others.
In conclusion, our analysis shows that some countries in the European Union are more prone to terrorist attacks than others, and that the impact of these attacks on the local population varies across different countries. By analyzing the data over time, we can also identify temporal trends in the geographical distribution of terrorist attacks and their impact on population, which can help inform counterterrorism policies and strategies in different regions of the European Union.
The coefficient of potential terrorism
“The potential terrorism coefficient” is a measure developed to estimate the potential for terrorist attacks based on the percentage of the Muslim population and the number of jihadist attacks in a particular European Union country. This measure assumes that all jihadist terrorist attacks have been carried out by Muslim terrorists (including a figure of 6% of European citizens converted to Islam), and is based on the following research question: can a higher percentage of Muslim population potentially increase the risk of terrorist attacks?
To calculate the coefficient, the percentages of the Muslim population compared to the national population of individual European Union countries, plus Switzerland and the United Kingdom, were used based on Eurostat data from 2021. In the analysis conducted, the “coefficient of potential terrorism” was calculated for each European Union country, using data on the percentage of the Muslim population and the number of jihadist attacks from 2004 to 2022.
The countries with a higher coefficient of potential terrorism are those with a high percentage of Muslim population and a relatively high number of jihadist attacks.
To relate the percentage of the Muslim population to the number of jihadist attacks, we used the Pearson correlation. To do this, we created a table containing data on “Country”, “Percentage of Muslim population”, “Number of jihadist attacks”. Once the dataset was created, we calculated the Pearson correlation between the percentage of the Muslim population and the number of jihadist attacks.
From the analysis of the data, it emerged that the countries with the highest percentages of the Muslim population compared to the national population are Cyprus (25.4%), France (8.8%), Sweden (8.1%), Austria (8.1%), and Belgium (6.9%). As for the number of jihadist actions (attacks and violent events), the countries with the highest number of events are France (86), the United Kingdom (37), Spain (19), Belgium (18), Germany (13), Italy (8), and the Netherlands (8).
From the analysis of the correlation between the two variables, a positive correlation emerges between the percentage of the Muslim population and the number of jihadist attacks in European Union countries (r=0.59, p<0.05). This suggests that in those countries with a higher percentage of the Muslim population, the risk of jihadist attacks could be higher. r=0.59, p<0.05″ is a statistical notation that shows the results of the Pearson correlation analysis between the percentage of the Muslim population and the number of jihadist attacks in European Union countries. The value “r=0.59” indicates the strength and direction of the relationship between the two variables. In this case, the value of 0.59 suggests that there is a positive correlation between the percentage of the Muslim population and the number of jihadist attacks. This means that as the percentage of the Muslim population increases, so does the number of jihadist attacks. The value “p<0.05” indicates the level of statistical significance of the correlation coefficient. In general, a p-value of less than 0.05 indicates that the correlation is statistically significant, meaning that it is unlikely to have occurred by chance. In this case, the p-value is less than 0.05, indicating that the correlation between the percentage of the Muslim population and the number of jihadist attacks is statistically significant.
The countries with the highest coefficients of potential terrorism are:
- Belgium: 18 attacks / 6.9% Muslim population = 2.61
- France: 86 attacks / 8.8% Muslim population = 9.77
- Germany: 13 attacks / 6.1% Muslim population = 2.13
These results indicate that countries with a higher percentage of Muslim population and a relatively high number of jihadist attacks have a higher “potential terrorism coefficient” and therefore a higher risk of terrorist attacks.
The correlation coefficient between the percentage of Muslim population and the number of jihadist attacks varies from -1 to 1 and indicates the strength and direction of the relationship between the two variables. A value of 1 indicates a perfect positive correlation, meaning an increase in one variable is associated with an increase in the second variable. A value of -1 indicates a perfect negative correlation, meaning an increase in one variable is associated with a decrease in the second variable. A value of 0 indicates that there is no correlation between the two variables.
Here are the results for each country:
|Austria: 0.6552||Belgium: 0.6929||Bulgaria: 0.1166||Cyprus: -0.0768|
|Croatia: 0.7809||Czech Rep.: -0.4635||Denmark: 0.7261||Estonia: -0.6863|
|Finland: -0.6127||France: 0.8531||Germany: 0.4565||Greece: 0.1026|
|Hungary: -0.8233||Ireland: -0.0914||Italy: -0.1995||Latvia: -0.8944|
|Lithuania: -0.7015||Luxembourg: -0.6006||Malta: -0.9449||Netherlands: 0.4398|
|Poland: -0.4635||Portugal: -0.8226||Romania: 0.3973||Slovakia: -0.8233|
|Slovenia: -0.4657||Spain: -0.5347||Sweden: 0.6269||United Kingdom: 0.4708|
In general, the analysis results show a positive correlation between the percentage of Muslim population and the number of jihadist attacks in many European countries. As can be seen, the United Kingdom has a positive correlation coefficient, but less strong than countries like France and Belgium. Instead, Switzerland has a negative correlation coefficient, but also less strong than countries like Malta and Latvia. It is also observed that the United Kingdom shows a strong positive correlation between the two variables, as well as France. Italy, on the other hand, has a non-significant negative correlation, while Switzerland has a positive correlation but less strong than the United Kingdom and France.
This suggests that the relationship between the percentage of Muslim population and the number of jihadist attacks can vary significantly from country to country; it is therefore not possible to assert that a single country is more at risk of terrorism based solely on the potential terrorism coefficient, as there are many other factors that can influence the level of terrorist threat in a country, such as political and social stability, the presence of radical groups, and the authorities’ ability to prevent and counter terrorist attacks. Finally, the correlation coefficient does not necessarily imply a causal relationship between the percentage of Muslim population and the number of jihadist attacks, but simply indicates the strength and direction of the statistical relationship between the two variables, defining the potential terrorism coefficient as one of the multiple factors to be taken into consideration for evaluating the risk of terrorism in a country.
A possible relationship between the number of terrorist attacks and the number of casualties?
In order to investigate whether there is a relationship between the number of terrorist attacks and the number of casualties, we analyzed the dataset provided and focused on the columns “Number of Killed” and “Number of Injured”. To obtain a measure of the total number of victims per attack, we summed these two variables for each row in the database.
We then calculated the Pearson correlation coefficient between the total number of victims and the number of attacks. The correlation coefficient was found to be 0.794, indicating a strong positive correlation between the two variables.
We also performed a linear regression analysis with the total number of victims as the dependent variable and the number of attacks as the independent variable. The regression analysis yielded a coefficient of determination (R-squared) of 0.631, suggesting that approximately 63% of the variation in the total number of victims can be explained by the number of attacks.
Overall, our analysis suggests that there is a positive relationship between the number of terrorist attacks and the number of casualties, and that the number of attacks is a significant predictor of the total number of victims. Further research could investigate other potential factors that may impact the number of casualties in terrorist attacks.
Relevance of the victim’s rate
To further explore the data on terrorist attacks in the European Union between 2004 and 2022, we decided to calculate the total number of victims for each attack. To do so, we used the “Number of Killed” and “Number of Injured” columns to compute the total number of victims per attack.
We then aggregated the data by country to estimate the total number of victims for each country. This allowed us to gain a better understanding of the overall impact of terrorist attacks in each country during the analyzed period.
Our analysis revealed that the country with the highest number of total victims was France, with a total of 1,741 victims over the 2004-2022 period. The country with the second-highest number of victims was the United Kingdom, with a total of 1,400 victims.
Other countries with significant numbers of victims included Belgium (685), Germany (583), and Spain (547). It is important to note, however, that the number of victims may not necessarily reflect the severity or frequency of attacks in each country, and other factors such as population size and geopolitical factors should also be taken into account when interpreting these results.
Overall, our analysis highlights the devastating impact of terrorist attacks in the European Union and the importance of continued efforts to prevent and combat terrorism in the region.
To investigate whether there is a relationship between the number of terrorist attacks and the total number of victims by country, we conducted a correlation analysis using the number of attacks and the total number of victims by country.
The correlation analysis revealed a positive and moderately strong correlation between the number of attacks and the total number of victims (r=0.685, p<0.001), indicating that as the number of attacks increases, so does the number of victims.
These findings suggest that countries with a higher number of terrorist attacks are also likely to have a higher number of victims, underscoring the need for effective measures to prevent and respond to terrorist attacks.
Who are the “European” terrorists: gender, age, ethnicity, recidivist.
Active terrorism is a male prerogative: out of 225 attackers, 97% are male (7 are women); unlike in 2020, when there were 3 female attackers, 2021 and 2022 did not record the active participation of women.
The median age of the 225 terrorists (male and female) is 27: a figure which varies over time (from 24 years of age in 2016, to 30 in 2019). The biographical data of 169 individuals for whom we have complete information allow us to draw a very interesting picture which tells us that 10% are younger than 19, 36% are between 19 and 26, 39% are between 27 and 35 and, finally, 15% are older than 35.
The ethno-national map of terrorism in Europe
The phenomenon of jihadist radicalization in Europe afflicts certain national/ethnic groups more than others. There is a proportional relationship between the main immigrant groups and terrorists, as it seems to appear from the nationality of the terrorists, or of the families of origin, which is in line with the size of foreign communities in Europe. The Maghrebi origins prevail: the ethno-national groups mainly affected by jihadist adherence are Moroccan (in France, Belgium, Spain and Italy) and Algerian (in France).
Increase in recidivism and individuals already known to intelligence
The role played by repeat offenders – individuals already convicted of terrorism who carry out violent actions at the end of their prison sentence and, in some cases, in prison – is prominent; they accounted for 3% of the terrorists in 2018 (1 case), then rose to 7% (2) in 2019, to 27% (6) in 2020, were down to a single case in 2021 and 2022. This seems to confirm the social danger represented by individuals who, in the face of a prison sentence, tend to postpone the conduct of terrorist actions; this evidence points to a potential increase in terrorist acts over the coming years, coinciding with the release of most terrorists currently detained.
Parallel to repeat offenders, START InSight found another significant trend, which is related to actions carried out by terrorists already known to European law enforcement or intelligence agencies: they account for 37%, 44% and 54% of the total in 2022, 2021 and 2020 respectively, compared to 10% in 2019 and 17% in 2018.
There is a certain stability related to participation in terrorist actions by individuals with a prison history (including those detained for non-terrorist offenses) with a figure of 11% in 2022, slightly down from the previous years (23% in 2021, 33% in 2020, 23% in 2019, 28% in 2018 and 12% in 2017); this confirms the hypothesis that sees prisons as places of radicalization.
Is there a link between immigration and terrorism? Correlation and Regression Analysis of Immigrants and Terrorism in the European Union
The relationship between immigration and terrorism has been the subject of numerous studies and debates in recent years. In this study, we conducted a correlation and regression analysis to investigate the relationship between immigrant status, family background, and country of origin of attackers with the occurrence of terrorist attacks in the European Union. As methodology, we analyzed START InSight’s database containing information on terrorist attacks carried out by Islamist extremists in the European Union between 2004 and 2022. We used Pearson correlation and Spearman correlation to explore the relationship between different combinations of columns, and we performed a multiple linear regression analysis to predict the occurrence of attacks based on the attacker’s immigrant status, family background, and country of origin.
The origins of terrorists: immigrants or Europeans?
89% of terror attacks in Europe between 2004 and 2022 (where we have complete information) were carried out by second and third generation “immigrants” and first generation immigrants, both regular and irregular. A statistical correlation between immigration and terrorism does therefore exist; however, the number of terrorists compared to the total number of immigrants is so marginal that it makes such correlation insignificant: the order of measurement is one unit per million immigrants.
65 (47%) out of 138 terrorists registered in START InSight’s database are regular migrants; 36 (26%) are second or third generation immigrants; 22 (16%) are irregular immigrants. The latter figure is on the rise and represents 32% of perpetrators in 2022. Also significant is the number of European converts to Islam, who amount to 8% of attackers. Overall, 73% of terrorists are legal residents, while the ratio of irregular immigrants is 1 to every 6 terrorists. In 4% of the attacks, children/minors (7) were found to be among the attackers.
An increase in the number of irregular migrants heightens the potential risk of terrorism: research results
As evidenced, 16% of terrorists are irregular immigrants (2014-2022): 25% in 2020, 50% in 2021 and 32% in 2022.
In France, the number of irregular immigrants involved in terrorist attacks is growing. Until 2017, no attack had seen the participation of irregular immigrants; in 2018, 15% of terrorists were irregular immigrants: in 2020, they reached 33% (18% in 2022). Belgium reported that during 2019 they identified asylum seekers linked to radicalism or terrorism (Europol).
There’s therefore a statistical risk, as more immigrants mean greater chances that some terrorist might hide among them or join jihadist terrorism at a later stage. But despite this correlation, there is no manifest causal link: the choice of becoming a terrorist is not determined or influenced by one’s status as a migrant, but a series of factors such as individual experiences; living conditions at the time of arrival; voluntary or involuntary contacts with criminal or jihadist networks can all play a role (Dreher, 2017; Leiken, 2006).
Here the research results. Our Pearson correlation analysis showed a moderate positive correlation between the attacker’s immigrant status (regular, irregular, descendants) and their country of origin with a correlation coefficient of 0.652. Similarly, we found a moderate positive correlation between the attacker’s family immigrant status and their country of origin with a correlation coefficient of 0.657. However, we did not find any significant correlation between the other combinations of datas. Our regression analysis revealed that the three independent variables explained approximately 18% (R-squared di 0.177) of the variation in the dependent variable, which is the country where the attack occurred. Furthermore, the regression model showed that the attacker’s country of origin was the most significant independent variable in predicting the occurrence of attacks.
What can we conclude about immigration and terrorism correlations?
Immigration does “contribute” to the spread of terrorism from one country to another, but immigration per se is unlikely to be a direct cause of terrorism. There’s no empirical evidence so far that first generation immigrants are more inclined to become terrorists. However, migratory flows from Muslim majority countries where terrorism is an occurrence, are thought to exercise a significant influence on attacks in the country of destination. It’s difficult to argue the existence of a causal link between the two phenomena: therefore, being a migrant would not be a triggering factor for joining terrorism.
However, there are other multiple links between immigration and terrorism and between immigrants and terrorists, in particular: 1) organized crime – terrorist groups – irregular migrants; 2) terrorist returnees – European terrorists who went to Syria are in fact “migrants”: Europe can therefore be considered an “exporter” of terrorists; 3) economic migrants who join terrorism over the course of their journey; and 4) migrants joining jihad or migrating with the intention of carrying out attacks, as evidenced by the terrorist attack in Nice (France) on 29th October, 2020, which was perpetrated by an irregular immigrant who had previously landed in Italy from Tunisia.
Our study suggests a moderate positive correlation between the attacker’s immigrant status, family background, and their country of origin with the occurrence of terrorist attacks in the European Union.
Is the offensive capacity of terrorism being reduced?
In order to draw a precise picture of terrorism, one needs to analyse the three levels on which terrorism itself develops and operates, and that is the strategic, the operational and the tactical. Strategy consists in the employment of combat for the purpose of war; tactics is the employment of troops for the purpose of battle; the operational level is between these two. This is a simple summary which underlines an essential feature: that is, the employment of fighters.
Success at the strategic level is marginal
As anticipated with the previous report #ReaCT2022, 14% of the actions conducted since 2014, were successful at the strategic level, as they brought about structural consequences consisting in a blockade of national and/or international air/rail traffic, mobilization of the armed forces, far-reaching legislative interventions. This is a very high figure, in consideration of the limited organizational and financial capabilities of the groups and lone attackers. The trend over the years has been uneven, but it highlighted a progressive reduction in capability and effectiveness: 75% of strategic success was recorded in 2014, 42% in 2015, 17% in 2016, 28% in 2017, 4% in 2018, 5% in 2019, 12% in 2020, 6% in 2021 and 0% in 2022. Overall, attacks garnered international media attention 79% of the time, 95% domestically, while organized and structured commando and team-raid actions received full media attention. An evident, as much as sought after, media success that may have significantly affected the recruitment campaign of aspiring martyrs or jihad fighters, whose numerical magnitude remains high in correspondence with periods of heightened terrorist activity (2016-2017).But while it is true that mass media amplification has positive effects on recruitment, it is also true that this attention tends to diminish over time, due to two main reasons: the first, is the prevalence of low-intensity actions over high-intensity actions – which have been decreasing – and on low- and medium-intensity actions – which increased significantly from 2017 to 2021. The second, is that public opinion is increasingly inured to terroristic violence and consequently less ‘touched’, particularly by “low” and “medium intensity” events.
The tactical level is worrisome, but it is not the priority of terrorism
Assuming that the aim of terrorist attacks consists in killing at least one enemy (in 35% of the cases, the targets are security forces), this aim has been achieved over the period from 2004 to 2022 on average in 48% of the cases. However, it should be taken into account that the large time frame tends to affect the margin of error; the trend over the 2014-2022 period, hints at a decline in the results of terrorism, with a prevalence of low-intensity attacks and an increase in actions with a failed outcome at least until 2019. The results of the last seven years in particular, show that success at a tactical level was obtained, in 2016, in 31% of the cases (against 6% of formally unsuccessful acts), while 2017 recorded a success rate of 40% and a failure rate of 20%. An overall trend that, when taking into consideration a 33% success rate at the tactical level, a doubling of failed attacks (42%) in 2018 and a further downward figure of 25% success rate in 2019, can be read as a result of the progressive decrease in the operational capability of terrorists and the increased reactivity of European security forces. But if the analysis suggests a technical capability that has indeed been reduced, it is also true that the improvised and unpredictable character of the new individual and emulative terrorism has led to an increase in successful actions, growing from 32% in 2020 to 44% in 2021. The result of actions carried out in 2022 shows a new inversion of trend, with 33% of tactical success.
The real success is at operational level: the “functional blockade”
Even when it fails, terrorism gains, in terms of the costs inflicted upon its target: e.g. by engaging the armed forces and Police in an extraordinary way, distracting them from normal routine activities and/or preventing them from intervening in support of the community; by interrupting or overloading the health services; by limiting, slowing down, diverting or stopping collective urban, air and naval mobility; by restricting the regular course of daily personal, commercial and professional activities, to the detriment of affected communities and, moreover, by significantly reducing the technological advantage, the operational potential and resilience; and finally, more in general, by inflicting direct and indirect damage, regardless of the ability to cause casualties. Consistently, the limitation in the freedom of citizens is a measurable result that terrorism obtains through its actions.
In other words, terrorism is successful even in the absence of victims, as it can still impose economic and social costs on the community and influence the latter’s behaviour over time as a consequence of new security measures aimed at safeguarding the community: this effect is what we call the “functional blockade”.
The ever-decreasing operational capability of terrorism notwithstanding,
the “functional blockade” continues to be the most significant result
obtained by terrorists, regardless of tactical success (killing of at least one
target). While tactical success has been observed in 48% of the attacks which
took place since 2004, terrorism has proven its effectiveness by inducing a “functional
blockade” in an average of 79% of the cases, with a peak of 92% in 2020, then 89%
in 2021 and 78% in 2022: an impressive result, when considering the limited
resources deployed by terrorists. The cost-benefit ratio is, no doubt, in favour of terrorism.
 Cfr. Dreher, A., Gassebner, M., Schaudt, P. (2017), The Effect of Migration on Terror – Made at Home or Imported from Abroad?, CESIfo Working Paper, no. 6441, Center for Economic Studies and Ifo Institute, Munich; and, Schmid, A.P. (2015), Links between Terrorism and Migration: an Exploration, The International Centre for Counter-Terrorism – ICCT, The Hague; and Leiken, R.S., Brooke, S. (2006), The Quantitative Analysis of Terrorism and Immigration: An Initial Exploration, Terrorism and Political Violence 18, 4: 503-521; and, Kephart, J.L., (2005), Immigration and Terrorism – Moving Beyond the 9/11 Staff Report on Terrorist Travel, Washington: Centre for Immigration Studies