Threat assessment


The European Union (EU) has for some time regarded terrorism as a threat to both the internal and external security of the Union. Over the years, the countries in the EU have faced terrorism on different occasions. However, at present the internal and external variants of the threat are strongly interconnected: the problem of foreign fighters and returners, as well as the flow of refugees towards Europe as a result of the war and terror in Syria and Iraq, transport the danger from the internal to the external arena and vice versa. The threat of terrorism also threatens the community of values that stand for democracy and the rule of law.‍[1] Europol therefore refers to a growing threat in comparison with recent years.‍[2] In addition to the above elements, this is also related to the fact that the threat assessment has become increasingly diffuse due to the great diversity of modus operandi, the choice of targets, the degree of organisation and the use of weapons. At present, the threat is even assessed as extremely serious.

In addition to the ‘hard’ side of terrorism, the EU also devotes attention to the ‘softer’ side by emphasising the importance of the resilience of democracies. The Global Strategy, for example, expresses an ambition to support the promotion of human rights, fundamental freedoms, the rule of law, justice, solidarity, equality, the prohibition of discrimination, pluralism and respect for diversity.‍[3] In that regard, a link is also made with the fact that the lack of these makes societies more vulnerable to radicalisation and terrorism. Interestingly enough, while this lack of resilience to horizontal tensions or polarisation is seen as a threat that can also have implications for the internal EU, it is regarded as less of a threat that is already manifesting itself within the EU. The European Agenda on Security does warn that EU policy against extremism must not lead to stigmatisation of a particular group, but does not go further than, for example, conducting an analysis of the extent to which this already exists.‍[4]

The attention to the ‘softer’ side of terrorism is nevertheless understandable. Where major differences in welfare, labour market opportunities, (political) exclusion or defective participation or integration, marginalisation and discrimination are coupled with fears of the loss of what is familiar (for example as a result of large refugee flows or fears of terrorism), this can lead to sharply differing views and there is a risk of polarisation in society. Where different camps take very extreme positions, this can even lead to radicalisation of different ideologies and in the worst case, to a form of violent extremism. Because of this risk, a number of important factors applying to this development are considered in this contribution.

This field is not only under pressure because people from the countries around Europe are making attempts to flee to Europe, but also because there are horizontal tensions within the EU which are taking on such forms that they are placing social resilience under pressure. The exponential growth in the refugee flow in recent times and fears of terrorism have led to a hardening of the debate and appear to be driving society into opposing camps. This has already led to rowdy demonstrations in municipalities against the arrival of refugee centres and (violent and tasteless) protests by nationalist and extreme right-wing movements, which in turn led to counter-demonstrations.

This threat assessment is based on the trends in the number of terrorist attacks and the number of victims (as a base rate), and the impact on this of the different elements that can lead to an increase or decrease in the base rate. These elements, or determining factors, are the emergence of or decline in certain forms of extremism, developments in society that can influence the fundamental causes of radicalisation, and the developments relating to the modus operandi, level of organisation, choice of targets and choice of weapons (see Table 1).

Table 1
Terrorism threat assessment
Terrorism trends

The base rate

Trend analyses for the past 10 years (2004-2014) show a fairly consistent, average increase in the number of terrorist attacks (see Figure 1).‍[5] The Europol data on failed, foiled and successful attacks, which include 2015, also confirm this picture.‍[6] Although the data up to 2014/15 present a stable picture, it would not be correct to continue this line and expect a similar threat. From 2015, a break in the trend appears to arise, in which, for the first time, several large-scale attacks occur in a year.

Figure 1
Number of terrorist attacks in Europe[7]

2015 shows a major departure from the data for the 2004-2014 period (see Figure 1) in the number of fatalities. The number was very high in 2004 as a result of the terrorist attack on public transport in London and a peak also occurred in 2005 as a result of the attacks in Madrid, but in subsequent years, the numbers were fairly consistently low and remained below a maximum of 15 fatalities (see Figure 1). The 175 fatalities in 2015 therefore shows a very abrupt increase. Europol also confirms these numbers.‍[8] Another 360 people were injured as a result of terrorist attacks.‍[9] Furthermore, this increase continued in the first half of 2016 as a result of the attacks in countries including France, Germany and Belgium.

Determining factors

What can be expected for the future on the basis of determining factors? Although these are not predominant in numbers,‍[10] Europol ascribes the increased threat to jihadist terrorism and the closely associated phenomenon of foreign terrorist fighters, who travel from and to the conflict regions, primarily in Syria and Iraq. The figures that provide an insight into the potential of foreign fighters are not reassuring. In the countries around Europe (see Figure 2) and in the rest of the world (see Figure A in the pop-out window), there is a constant increase in the number of attacks. This has implications for Europe. The increase in terrorist activity in the countries around Europe, particularly by terrorist organisations that manifest themselves very actively in the Middle East and the North African region, has an attraction for many young people in Europe. They try to join these groups as foreign terrorist fighters, but can also decide to return to Europe at a certain point, possibly with plans to commit attacks there.

Figure A
Number of terrorist attacks in the rest of the world[31]
Figure 2
Number of terrorist attacks in countries bordering Europe[11]

Strongly related to this are the expected consequences of the battle against Islamic State (IS). Particularly the call of IS on its supporters not to travel to the caliphate but to commit independent attacks in the West, and the risks associated with returners have a major impact on the increased risk of an attack.‍[12] Furthermore, it is assumed that in the first instance, losses by IS and the potential collapse of the caliphate will lead to a wave of terrorist acts in other parts of the world (including Europe).‍[13] Historical research shows that in the past, too, military successes against terrorist organisations initially resulted in more attacks.‍[14]

A second element concerns a multifaceted threat assessment. There is a diversity in the choice of targets (police and the military, and civilians) at public (leisure) locations and (sporting) events or national celebrations (14 July in Nice), with more or less symbolic value (in the latter case, in particular with extreme right-wing terrorist attacks on refugee centres and mosques). There is also a great diversity in modus operandi and the use of weapons (explosives or even day-to-day equipment). There are also differences in the complexity of the implementation and organisation (lone wolf actions or coordinated operations with simultaneous attacks made at several locations by different cells). On the basis of the START data for the past 10 years, there was already a changeable picture regarding the types of attack and the use of weapons (see Figures 3 and B).

Figure B
Types of weapons used in attacks in Europe[32]
Figure 3
Types of attack in Europe[15]

A third element concerns a gradually rising trend in the EU in attacks committed by lone wolves as opposed to attacks committed by (organised) groups since 2010 (see Figure 4). This may be attributable to the doctrine embraced by Al Qaida after the death of Osama bin Laden in 2011.‍[16] The call from IS in early 2015 to all Muslims in Europe to commit attacks on all ‘crusaders’ will certainly strengthen this development. In addition, the available data appear to suggest that on average, attacks committed by lone wolves cause more fatalities than other types of attacks (see Figure C). At the same time, IS terrorist cells operating within the EU and an accelerated radicalisation process that make detection more difficult are also taken into account.‍[17] The number of attacks by lone wolves has also increased. All in all, this increasing changeability through the variations in choice of target, modus operandi, level of organisation and choice of weapons contribute to an increase in the threat of terrorism. The predictability of a planned attack is diminishing and it is therefore more difficult for security services to detect and prevent them.

Figure C
Average number of deaths per attack, lone wolves vs. more than one perpetrator[33]
Figure 4
Number of perpetrators of attacks in Europe[18]

A fourth and final factor concerns an interplay of social developments that are seen in the literature on radicalisation as ‘push factors’ that can play a role (if not the only role!) in a process of radicalisation, and can at least lead to an increase in horizontal tensions.‍[19] It should be noted here that no direct causal link can be shown to radicalisation for any of these factors, which only act as an indicator of vulnerability to radicalisation or extremist ideas. We consider some important factors here for forecasting future developments on the basis of the trend analysis. This concerns factors relating to (perceptions of) discrimination and exclusion, welfare distribution, poverty and unemployment, and perceptions on immigration. With the latter factor, in the first instance there primarily appears to be a risk of an increase in horizontal tensions with growing negative perceptions of immigration, as shown by the many demonstrations and riots in response to the enormous number of refugees recently flowing into Europe.

A special Eurobarometer on discrimination in the EU reports that 64% of discrimination takes place on the basis of ethnic background and 50% on the basis of religion.‍[20] 12% of the respondents said that they belonged to a group at risk of discrimination, 5% of these due to a religious background and 4% due to an ethnic background. Almost half of them (46%) believe that discrimination based on ethnic background takes place in the labour market. However, overall, discrimination does not appear to be growing. In the 2004-2014 period, the main relevant form of discrimination took place on the basis of skin colour, race, or national or ethnic background. While there appeared to be a slight increase until 2012, a somewhat sharper fall was seen after 2012 (see Figure D). Discrimination on the basis of religion also rose very gradually in the 2004-2014 period (see Figure D). On the basis of this long-term trend, discrimination based on skin colour, race, or national or ethnic background can be expected to stabilise or continue to fall slightly in the coming five years. The long-term trend in discrimination based on religion indicates a continuing increase in the coming five years. This form of discrimination can make a specific group more vulnerable to radicalisation.

Figure D
Discrimination experienced by Europeans[34]

Another push factor can arise from (economic) inequality and poverty. According to the Eurostat methodology, there are three important aspects in measuring whether people belong to the group that runs the risk of living in poverty, and where there is social exclusion: monetary poverty, serious material deprivation and a very low employment level.‍[21] With regard to the first point, the Gini score, which shows the income distribution between individuals and households within an economic system, shows a slight movement towards more equality in the 2003-2012 period. The data show that this income inequality is far smaller than in the rest of the world (see Figure E).

For the second factor, serious material deprivation, the score shows that there are still large differences between European member states (2006-2015).‍[22] At the same time, the largest difference that has existed between countries almost halved during this period. Since 2010, the European average has been measured, but this shows that there is a slight increase in this problem (see Figure F).

Figure E
Gini coefficient, EU and the world[35]
Figure F
Serious material deprivation in Europe[36]

For the third indicator, labour participation and unemployment, the overall level of unemployment remained unchanged between 2004 and 2014, although naturally, the economic crisis resulted in a temporary increase in unemployment. If the youth unemployment figures (ages 15 to 29) are separated, the same trend proves to have been followed as for the general unemployment figures, but the overall labour participation in this category is significantly lower than in the working population as a whole in the EU. In 2015, the percentage of unemployed persons in the entire labour force was 9.4%, while among the young, it was 20.4%.‍[23]

The above factors provide an overall assessment relating to the poverty and social exclusion of a percentage of the population. The trend between 2005 and 2014 shows that there was a decline in poverty and social exclusion until 2009, followed by a rise again until 2012. With a slight fall since 2012, the level since 2005 has become somewhat lower.‍[24] In as far as this aspect has an influence on the risks of radicalisation, a decrease in the risk would therefore be expected on the basis of this trend.

However, groups that run the highest risk of social exclusion or of falling into poverty are women, young people (aged between 18 and 24), single parents, the unemployed, the low-skilled, children of parents with low educational qualifications, people from rural areas and immigrants from outside the EU.‍[25] Young people are extra vulnerable: they account for just under 30% of the group at risk of poverty and social exclusion. This group is therefore trailing the rest, which can reinforce a sense of marginalisation and can therefore mean increased vulnerability to radicalisation, certainly in view of the fact that the foreign fighters of today fall into the 18 to 28 age category.‍[26]

Finally, the last factor that can contribute towards an increase in horizontal tensions and event to forms of radicalisation are the perceptions relating to immigration. There has been a substantial rise in asylum requests since 2006 and even a sharp rise since 2012. The trend analysis of illegal immigration also shows a sharp increase since 2014. However, there is a lack of convincing information on how the recent break in the trend concerning legal and illegal immigration has affected the perceptions of the population on immigration.‍[27] For the 2004-2014 period, there appears to be a slight increase, from just below average to just above average (see Figure G) and, therefore, perceptions appear to be largely positive (see Figure H). However, these figures barely reflect perceptions concerning the recent sharp increase in both legal and illegal immigration. It is predictable that this latest development will lead to a fall in the scores, but on the basis of existing data, it is not possible to predict the extent to which that fall will quickly reverse as soon as there is a (sharp) fall again in both legal and illegal migration.

Figure G
Opinion on immigrants in Europe[37]
Figure H
Opinion on impact of immigrants on culture and economy in Europe[38]

Impact and shocks

What do these trends and factors mean for the overall threat analysis for 2021? The above long-term trends relating to horizontal tensions offer few leads for predictions for the upcoming five years, firstly because developments in general had little significance and secondly because the causal relationship cannot be established satisfactorily on the basis of these data. Only with regard to discrimination on the basis of religion and the risk of poverty and social exclusion among young people is it possible, on the basis of the trend analysis, to anticipate an increase which could lead to an increased risk of radicalisation.

By contrast, the developments in the field of terrorism and (radicalisation to) violent extremism in the past two years show that a change has taken place with regard to the threat assessment in Europe. While in the years 2006-2014 there was still a linear rising trend in the number of attacks, the past two years show a sudden peak in the number of fatalities and the number of attacks motivated by jihadist extremism. The long-term trends from the past could suggest for the future that there is a temporary peak which could be short-lived. However, the assessment is that this is more likely to be a break in the trend that has a major impact on the threat assessment. The expectation on the basis of the (recent) past is that this sharper increase will therefore continue in the coming years.

The probability of (attempted) terrorist attacks in several European countries in the coming five years is very high, bordering on certainty, and in view of the trend analysis, both government agencies or government officials and private citizens can be expected to be chosen as targets, with a great variety in the choice of weapons. Furthermore, the great variety in modus operandi and the level of organisation make the threat still more diffuse, which is a particular challenge for security services.

‘Unexpected’ events that could change this assessment are always conceivable. The Clingendael Expert Survey identifies these ‘shocks’ (see Figure I). According to the outcomes of this survey, the disintegration of the EU is regarded as the scenario most likely to foster a break in the trend in relation to the threat assessment. The impact of this shock is assessed as high to very high. The risk that IS will succeed in manipulating the security risks in such a way that Western societies turn against Muslims is regarded as about as likely as it is unlikely, but any impact of this if it succeeds would nevertheless be high. The risk of simultaneous terrorist attacks in several EU capitals is regarded as just as likely as it is unlikely. However, the impact of such attacks is assessed as high. Finally, the risk that Boko Haram will expand its ‘sphere of operations’ to Europe is regarded as highly likely, with any impact of this being estimated as neither low nor high. All in all, the outcomes of the Clingendael Expert Survey support the earlier analysis that the risk of an attack is very high and that the impact of this would be substantial. This also endorses the analysis that there is currently a break in the trend, and that the shock scenarios will not make any material change to the threat analysis.

Figure I
Possible shocks in terrorism threat assessment (N=15)
Possible shocks in terrorism threat assessment (N=15)


Boko Haram expands into Europe
Civil war or major social unrest in France
The US pursues a more isolationist foreign policy and no longer prioritises Europe
European Union disintegrates
IS succeeds in turning Western societies against Muslims
Multiple simultaneous terrorist attacks in EU capitals
Russia attacks one or more Baltic states

The international terrorism regime

International cooperation in the field of terrorism and the way in which this responds to developments is examined below. A first observation is that no coordinated policy has been formulated in relation to tensions between groups at either the international or the European level in order to counter the increase in horizontal tensions.‍[28] Furthermore, no separate risk assessments are made. This reinforces the idea that developments in this regard will be very fragmentary, and that there is a risk that the different aspects and their inter-relationships will not be included adequately in the policy. For this reason, this analysis only addresses the question of how the international system deals with terrorism, although with attention to the soft side of terrorism control and the underlying radicalisation factors. An outline of the important actors is presented first, followed by trends in the development of norms and rules and finally, the degree of compliance.

Actors and institutions

The international system concerned with control of terrorism is distinguished by a large number of actors who contribute towards terrorism control and prevention of radicalisation leading to violent extremism in different ways, at different levels and with different degrees of cooperation. This field is no longer the exclusive domain of sovereign states that regard it as an internal matter. In view of the cross-border nature of the problem, cooperation between states takes place at a bilateral level and in multilateral organisations (universal and regional). For the Netherlands, the cooperation at the universal level within the United Nations (UN) and at the regional level within the EU and the Organisation for Security and Cooperation in Europe (OSCE) are important, as is cooperation within the Global Counter-Terrorism Forum. The latter forum is an alliance between Western and Arab states and acts mainly as a driver of policy. It does not have a fixed structure, as is the case with other international organisations. Furthermore, it is a field in which non-state actors are increasingly claiming a position, with a view to designing a multi-disciplinary and multi-stakeholder approach.

At the same time, there appears to be a clear division of tasks where states primarily support a punitive approach and NGOs design prevention, together with states. States, and to a lesser degree, international organisations focus primarily on the exclusive field of the hard, repressive and punitive (sometimes military) approach. The UN, for example, played a determining role in setting up a regime to control financing of terrorism and ordering national criminal law against terrorism and terrorism-related actions (without, however, defining ‘terrorism’ as such).

In prevention (both hard and soft), on the other hand, different actors play a role, and the cooperation between states, international organisations, NGOs and the private sector is regarded as increasingly important for an effective approach. Furthermore, this approach won support at the international level through the unanimous adoption of the UN Global Counter Terrorism Strategy in 2006, resolution 1624 of the UN Security Council (2005 – aimed at controlling incitement to terrorism and prevention by means of cooperation with civil society), the conclusions of the Bogota summit in 2013 and the White House summit in the field of Countering Violent Extremism in 2015. The importance of cooperation also applies for the approach to addressing radicalisation via the internet. Social organisations are better able to reach the target group here with their counter-arguments. The private sector should also play a role in identifying content regarded as dangerous and possibly removing it. In the policy of rehabilitation and reintegration of convicted terrorists or returning foreign fighters, it is also considered important that private persons, such as family and friends, and social organisations play a role in this process. In European countries and the countries bordering Europe, international organisations invest in improving relationships of trust between state and non-state actors in order to make prevention policy more effective. This is shown by the programmes of organisations such as the EU, the OSCE and the UN, and the budgets that are released for this.

Norms and rules

With regard to norms and rules (see Table 2), there are three important developments on the more repressive side. Firstly, the definition of terrorism. In accordance with the internationally accepted legality principle, it is necessary that it is predictable for which a person can be prosecuted. The lack of a definition at the international level can at least be described as very remarkable, as this creates scope for very varied interpretations. However, the definition did take place at the European level and at various other regional levels. At this level, it is easier to reach political consensus but it does result in varying norms being set. This appears to indicate a strong development in relation to setting of norms, but at the same time there is still disagreement on the precise rules and at some levels, the outcomes therefore differ between different countries. However, it is interesting to note that the differences relating to the precise formulation of the rules do not appear to hamper the further design of an institutional development. An example of this is provided by the embellishment of instruments such as the Financial Action Task Force or the Counter-Terrorism Executive Directorate (a sub-body of the Security Council), which is responsible for supervision of compliance. In addition, major steps forward have been taken in the fields of harmonisation of legislation, and the UN has played a major role in monitoring implementation and offering technical support.

Table 2
Key norms and rules



Exceptionalism concerning counter-terrorism measures.

Criminalisation of terrorism and membership of a terrorist organisation in treaties, Security Council resolutions, EU legislation and national legislation.

Respect for human rights (right to life, freedom rights).

Criminalisation of the financing of terrorism, Blacklisting/sanctions against regimes of individuals/groups involved in terrorism.

Condemnation of terrorism is all its forms.

EU Counter Terrorism Strategy.

International solidarity in countering terrorism (international terrorism is a threat to international peace and security).

Instruments such as the Financial Action Task Force or the Counter-Terrorism Executive Directorate as supervision of compliance.

UN Global Counter Terrorism Strategy.

In prevention (both hard and soft), there is a development towards international norms relating to the importance of prevention work and addressing underlying causes of radicalisation. In this sector, the issue is less to set rules, but there is more cooperation with multidisciplinary state and non-state actors, supported by financial funds that are made available for this. Due to the growing threat in recent years, in addition to the development from a hard approach alone to the inclusion of a more preventive approach in counter-terrorism, there appears to be a trend towards a new norm of ‘exceptionalism’: the fact that the circumstances are so unusual that they call for exceptional measures which are not always in line with a proportional consideration of, for example, freedom rights. After all, the call for more cooperation between international security services, more exchange of data, suspending the rights of suspects, the surrender of privacy by citizens or the announcement of an emergency in order to make more powers possible for authorities are consistently accounted for with a view to the exceptional circumstances. This development, in fact towards an ultimate form of institutionalisation, also exposes a conflict between basic values of out society, in which the norms of security and freedom battle for precedence. Certain measures, such as the recent burkini ban in France, can elicit criticism from human rights organisations and even the UN. Nevertheless, the UN and the Council of Europe were also criticised by human rights organisations and experts due to the absence of or inadequate definitions of terrorism or foreign (terrorist) fighters. The discussion concerning sharing of data by states and organisations sometimes leads to major controversies, sometimes even within individual organisations. The Passenger Name Records (PNR) dossier and the negotiations between the EU and the United States is a good example of this. The European Parliament is following this dossier very critically and has already overturned agreements reached on several occasions. There appears to be an undertow here which could undermine the progressive wave of greater cooperation in due course, and possibly also result in a spoke in the wheel of compliance with policy by member states.


On the repressive side, there is intensified cooperation on specific themes, or at least this is an aim. This applies, for example, with regard to police cooperation, cooperation in the field of information gathering, sharing information and border controls. Far from all countries are willing to commit to this to the same extent as yet. After all, this depends heavily on mutual trust. As a result, there is a group of leaders here. This is the case, for example, for the initiatives arising from the Global Counter-Terrorism Forum, which are drawn up in the form of good practices or memoranda and, therefore, have no binding effect in themselves, but are regarded as a driver for international policy. Cooperation in this field is therefore largely of a state nature. It is sometimes driven by individual states, sometimes by cooperation with international or regional organisations and sometimes by a leading group. Depending on the ambitions and the mutual trust, there is cooperation in the field of norms and rules and in a few cases, there is further institutionalisation.

However, the approach on the preventive side (both hard and soft) presents a somewhat fragmented and diffuse picture. In contrast to the cooperation and universal implementation on the hard side of terrorism policy, for the implementation in the field of prevention this arises primarily through the many different actors (both state and non-state), which are often unfamiliar with the role that another actor may play in the dossier, the lack of mutual trust, the ethical dilemmas that such forms of cooperation sometimes raise,‍[29] and the lack of a clear framework.

The quadrant chart and shocks

All in all, the past 10-15 years have been characterised by a change in the focus of policy from hard and oppressive (counter-terrorism) to more comprehensive (countering violent extremism) and preventive approaches (preventing violent extremism). This change is driven partly by the criticism of the hard, repressive and military campaign which predominated after the attacks on 11 September 2001. Furthermore, it became clear that this approach also created negative side-effects, as a result of which the important norms of the rule of law and respect for human rights came to play a more prominent role in policy-making. However, as mentioned above, the developments of the past two years in particular predict a turnaround in the other direction again.

In view of the developments relating to the threat assessment and the developments in the international system (see Figure 5), cooperation at both the state and the non-state level, and between the two can be expected to intensify by 2021 and to move increasingly towards consensus in the field of norms and rules, and in some areas will lead to more institutionalisation.‍[30]

Figure 5
The international regime: Terrorism (2016 – 2021)
The international regime: Terrorism (2016 – 2021)

How sure are we of this assessment of international cooperation? According to the outcomes of the Clingendael Expert Survey, the disintegration of the EU has a high score for probability and impact (see Figure J). Such a shock will have an impact on the level of cooperation. Other types of cooperation will become more likely (probably more incidental and opportunistic) and this could lead to the formation of more groups of leaders. The strategic shock of several simultaneous terrorist attacks in EU capitals is regarded as being just as likely as it is unlikely, and the impact of such an incident scores as almost high. In the event of a terrorist murder attempt on a political leader of one of the major powers, the impact on the institutional system for counter-terrorism is regarded as average to high. However, the experts regard the risk of this happening as (highly) unlikely. The effect of the latter two shocks, as has been shown in the past, is that steps to intensify cooperation and data exchanges will quickly follow. In other words, the expectations concerning the development of the international system in the field of cooperation in counter-terrorism are robust for potential unexpected shocks. These are more likely to strengthen rather than weaken the trend towards more cooperation.

Figure J
Possible systemic shocks related to terrorism (N=15)
Possible systemic shocks related to terrorism (N=15)


European Union disintegrates
Armed conflict between China and the US about Taiwan and/or the East/South China Sea
Islamic terrorists kill the leader of a major power
Several simultaneous terrorist attacks in EU capitals
Global financial crisis


The question that remains relevant is whether we are adequately prepared for the threats of tomorrow. To that end, it is important to make an estimate of how the threats could develop in the coming years and how the international system will jointly address these threats. This contribution has considered developments in the terrorism threat and a number of factors that influence the increase or decrease in horizontal tensions, which in turn are important for the resilience of society to radicalisation.

The trend analysis for the past 10 years would suggest a downward trend in the threat of terrorism, were it not for the fact that the past two years appear to indicate a break in the trend. This increase in the threat, primarily from jihadist terrorism, is attributable to the sharp increase in the number of foreign fighters and the threat arising from an increase in the number of returners. In addition, there appears to be a recent increase in extremist right-wing terrorism. The growing unpredictability of the threat, due to the great variety of modus operandi, choices of target and level of organisation of the terrorists, also contributes towards a probable scenario in which there will still be a continuing severe threat in 2021.

The factors that influence horizontal tensions and in some cases can contribute towards reduced resilience to radicalisation generally offer few leads for making reliable predictions. The only trends that are visible and show an increase that could lead to more horizontal tensions and possibly, even to radicalisation are those relating to discrimination on the basis of religion and the risk of poverty and social exclusion among young people. That does not mean that other factors do not play a role, only that the existing data are insufficiently clear to show a trend or a causal relationship.

Finally, it is important to bear in mind that the developments in the international system show a trend towards more cooperation. This does not mean that there is agreement on all the underlying norms and rules. However, despite the lack of clear agreement regarding rules or, for example, definitions, there is a trend towards more institutionalisation at both the state and the non-state levels. This development, which is driven primarily by the continuing perception of a constant serious threat, will have a mitigating effect on the success of terrorist operations.

See: European Union Global Strategy, Shared Vision, Common Action: A Stronger Europe. A Global Strategy for the European Union’s Foreign And Security Policy, June 2016, 16, link.
Europol, European Union Terrorism Situation and Trend Report, 2016.
European Union Global Strategy, op. cit.
European Commission, The European Agenda on Security, 28 April 2015, COM(2015) 185 final.
START, Global Terrorism Database, 2016, 30 June, link.
Europol, op. cit.
START, Global Terrorism Database, 2004-2015, link.
Europol, op. cit.
Europol, op. cit.
Of the 211 failed, foiled and successful terrorist attacks, 17 are attributed to terrorism motivated by jihad, 13 to extreme left-wing terrorism, 9 to extreme right-wing terrorism, 65 to separatist terrorism and 107 to organisations not specified in more detail (Europol, op. cit.).
START, Global Terrorism Database, 2004-2015.
Europol, op. cit., 6-7.
One could also cite the struggle in the Chechen Republic, the pressure on Hezbollah, the PKK and the National Liberation Front (FLN). See e.g. Kurth Conin, A. 2006. ‘How Al-Qaida ends; The decline and demise of terrorist groups’, International Security, 31(1), 30-31; Frisch, H. 2008. ‘Strategic Change in Terrorist Movements: Lessons from Hamas’, Studies in Conflict and Terrorism, 32(12), 1049-1065.
START, Global Terrorism Database, 2004-2015.
Europol, op. cit., 26.
START, Global Terrorism Database, 2004-2015.
See e.g.: Feddes, A. R., et al. 2015. , ‘Triggerfactoren in het Radicaliseringsproces’, Social Stability Expertise Unit, University of Amsterdam, September; Ranstrop, M. 2016. ‘The Root Causes of Violent Extremism’, RAN Issue Paper, January, link.
European Commission, Special Eurobarometer 437 (Discrimination in the EU in 2015).
Eurostat, Europe 2020 Indicators – poverty and social exclusion, March 2016, link.
Deprivation exists if at last four out of nine conditions are met. These conditions are that a person is unable to i) pay rent or gas/electricity bills, ii) heat the home sufficiently, iii) absorb unexpected expenses, iv) include meat, fish or equivalent proteins in the diet every other day, v) go on holiday for a week, vi) own a car, vii) own a washing machine, viii) own a colour TV and/or ix) own a telephone. (Id., 11).
Eurostat, Material Deprivation, 2006-2015, link.
Eurostat, op. cit.
Eurostat, op. cit.
Ginkel, B. van, and Entenmann, E. (Ed.), op. cit., 51.
The extent to which immigrants are good or bad for the economy and whether they enrich or undermine the culture of the country were measured, and in general terms, the extent to which immigrants create a better living environment in the country in which they settle.
The SDG agenda could play a role. There is also little attention to this subject in the G20.
This includes, for example, the discussion concerning the withdrawal of the duty of confidentiality of (medical) care providers in relation to their patients in favour of the security sector where there are concerns relating to radicalisation.
With this general conclusion, it should be noted that there are many different sub-fields in this system. In most fields there is a greater emphasis on norms and rules, but on some levels these are still in development (and on some levels, there are no norms or rules as yet).
START, Global Terrorism Database, 2004-2015, link.
START, Global Terrorism Database, 2004-2015, link.
START, Global Terrorism Database, 2004-2015, link.
European Social Survey (ESS), Subjective Well-Being, Social Exclusion, Religion, National and Ethnic Identity, 2004-2014, link.
World Bank, GINI Index, 2003-2012, link.
Eurostat, op. cit.
ESS, Politics, 2004-2014, link.
ESS, Politics, 2004-2014, link.

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