The Decline of ETA

por GEES, 23 de enero de 2002

When taking stock of the year 2002, the Spanish Minister of the Interior, Ángel Acebes, highlighted the success in the fight against ETA. Without self-satisfaction, as the Basque terrorist group  “keeps its capacity to cause pain and suffering”, he maintained that it was being proved that it was possible to defeat it “from the Law and from Democracy”.  Is that a sign of governmental overconfidence? In our opinion, it is not. Everything suggests that, after the short recovery that followed the ceasefire, the decline of ETA, that started in 1992, has intensified. Three factors account for that decline: the efficiency of the judicial system and of law enforcement agencies, the growing rejection of terrorism from society as a whole, and international cooperation, especially on the part of France.
These three factors cannot be analysed separately. The strength ETA had twenty years ago originated in its capacity to recruit militants and in the relative tolerance shown by France towards its activities, which provided it with a rearguard base out of the Spanish judicial authorities’ reach. The recruitment was easy, as it counted on the support of a minority though significant sector of Basque society that denied the legitimacy of the Spanish State. This social support led the governments in Paris not to take drastic measures against what some people considered a national liberation movement. Both factors, the social support to ETA, and French tolerance towards ETA’s activities in their territory, rendered the anti-terrorist actions of the Spanish governments difficult. Sometimes they resorted to indiscriminate repressive measures, that turned out to be counter-productive as they stirred up sympathies for ETA.
Like many other insurgent groups, ETA based initially its strategy on the action-repression-action principle. We can find an accurate description of this principle in the document Theoretical Bases of  Revolutionary Warfare, approved by ETA in 1964:
‘Suppose a situation in which an organized minority strikes material and psychological blows to the organization of the State, forcing it to respond and to violently repress the aggression. Suppose that the organized minority manages to escape repression, and that it falls on the masses. Finally, suppose that the minority manages to make rebelliousness instead of panic spread among the population, so that it helps and protects the minority against the State; the action-repression cycle is therefore ready to repeat itself with increasing intensity’.
Under the regime of  the Spanish dictator Francisco Franco this strategy did not work in so far as ETA could not manage to ‘escape repression’; however it worked very well in that it made repression fall ‘on the masses’, engendering within a sector of them a movement of support to the terrorist group. Therefore, when Franco died in 1975, ETA was almost dismantled, but it enjoyed a popularity that allowed it to recruit numerous militants and to mount a strong terrorist offensive from 1978. As can be observed in the following bar chart, the most tragic years as regards terrorism were those of the Spanish political transition to democracy. The largest number of murders took place in the years in which the Spanish Constitution (1978) and the Basque statute of autonomy (1979) were adopted, and the first Basque government and parliament were established (1980).

Therefore, most of the murders have been committed by ETA in a democratic Spain and in an autonomous Basque Country, with an aim to make the autonomic model fail, and to impose by force the secession of the Basque provinces and Navarra. On the other hand, ETA could hardly have obtained an important social support within a framework other than a dictatorial regime as hostile to every expression of Basque nationalism as the regime of Franco was.      
Successes and failures in 25 years of anti-terrorist policy
Once the Spanish democracy was consolidated, the threat posed by ETA decreased, but its terrorist activity kept at a high level during the 80’s and at the beginning of the 90’s. That prompted different responses, some of which proved to be counter-productive, whereas others led to a progressive weakening of ETA. Among the former we could mention the following:
  • Indiscriminate repression. The method that consisted of conducting raids upon the milieu of ETA, typical of the regime of Franco, but that has also been employed afterwards to a lesser extend, had one main drawback, i.e. that it led to the arrest of persons with no links to the terrorist group. It was also counter-productive in that it fed the wrong impression that it was ideas and attitudes that were persecuted, and not crimes, which damaged the legitimacy of the state in the eyes of a significant part of the Basque population.
  • Dirty war. The violent and illegal anti-terrorist actions, favoured by certain sectors of the Spanish administration, that inflicted several casualties among ETA terrorists and supporters, and even people with no links to the terrorist group, developed in two stages: a first stage from 1975 to 1981 and a second and better known stage from 1983 to 1987, in which the GAL[1] claimed responsibility for the attacks (Woodsworth 2002). The main objective of the GAL has allegedly been to force the French government to adopt a more inflexible attitude towards ETA terrorists, who planned in France the attacks they carried out in Spain. The French government changed its attitude in 1986, and it is difficult to assert whether that decision was influenced or not by the offensive of the GAL. However, there is no doubt that more important factors would have led to that change of attitude on the part of France, such as the consolidation of Spanish democracy, the cooperation between both countries within the European Community, and the growing international awareness as regards the global threat posed by terrorism. The negative consequences of the ‘dirty war’ are also evident. The moral prestige of the young Spanish democracy was tainted, and the attacks launched by the GAL led a sector of the Basque population not to accept the real nature of democratisation. It might be no coincidence that, according to opinion polls, the percentage of the Basque population that completely rejected ETA decreased from 1982 to 1987, to steeply  rise afterwards.
  • Attempts to negotiate. Negotiations were successful during the transition period, as they led to the dissolution of ETApm, one of the factions into which the original ETA had split. But the numerous attempts to negotiate undertaken later on by the governments of Felipe González lead to no positive result. Moreover, they could even have turned out counter-productive, as Ignacio Sánchez-Cuenca points out in an interesting essay (2001). Since ETA pursued at that time a strategy of attrition intended to pressure the State into acceptance of its secessionist demands, the attempts to negotiate made it think that its strategy was bearing fruit, and that the State was about to give in, so it had better build up the pressure. Two of the bloodiest attacks launched  by ETA, against a supermarket in Barcelona and against the living quarters of a Guardia Civil barracks in Zaragoza, took place in 1987, during the first stage of the negotiations of Algiers, the most important negotiations between the Spanish State and ETA.
  • Tolerance towards the milieu of ETA. Proceeding on the assumption, valid in itself, that the deep social roots of ETA answered to the fact that the regime of Franco offered no channel for political participation, the successive governments in Madrid and in Vitoria tended to think it suitable to offer the milieu of ETA room for legal activities, hoping that it would make them see how absurd it was to pursue the line of terrorism. Results were however contrary to expectations. Far from prevailing on the radical nationalists close to ETA to acknowledge the new framework for coexistence, a large network of organizations appeared, both legal and illegal, that adhere to the guidelines established by ETA, cooperate with its strategy, harass those who oppose the terrorist group and are a breeding ground for ETA activists.
To sum up, all the tactics employed that drift away from the principles of the rule of law, both those involving tough repression (dirty war, indiscriminate repression) and concessions to terrorism (negotiations with terrorists, tolerance towards criminal activities in the milieu of ETA), have produced negative results. However we believe that those measures that are in keeping with the spirit of democracy and with the respect for legality, have significantly contributed to the decline of ETA, i.e.:
·         the creation of a large democratic consensus in Spanish society as a whole, particularly  within Basque society, that has contributed to a significant withdrawal of support for the terrorist group;
·         the role of the judicial authorities, assisted by law enforcement agencies, clearing up terrorist crimes and imprisoning their perpetrators; indiscriminate measures against the milieu of ETA have been avoided, but effective collaborators have not been allowed to act with impunity; and
·         the enhancement of international anti-terrorist cooperation.
Before we analyse these questions in depth, it would be advisable to recall the strategic evolution of ETA, and the network of organizations headed by the terrorist group.
The strategic evolution of ETA
Experts like Florencio Domínguez Iribarren and Ignacio Sánchez-Cuenca have identified three stages in the strategic evolution of ETA. We could call them revolutionary warfare stage, strategy of attrition stage and nationalist front stage.
Revolutionary warfare. During the first stage, that would go approximately from 1968, the year of its first terrorist actions, to 1978, when the Spanish transition to democracy culminated in the adoption of the Constitution, the strategy of ETA found inspiration in the revolutionary wars of Third World countries, and terrorist actions were understood as the detonator of an armed insurrection through which the Basque people would snatch their independence from the Spanish state. The period of the transition to democracy seemed to be the most convenient to put that strategy into practice, but after the consolidation of democracy and the establishment of the autonomic system, the assumption that a popular insurrection in the Basque Country was possible lost credibility, even for the most fanatic ideologists.
The strategy of attrition. The second stage, from 1978 to 1998, was characterized by a strategy based on the assumption that terrorist pressure would force the State to renounce its principles and to give in to ETA’s claims. According to this strategy, terrorism was no longer a previous stage that, through an action-repression cycle, would end up triggering a massive insurrection, but the essential element that would lead straight to victory. The success of this strategy depended on the perseverance of the State and of the terrorist network; therefore, the widespread support of Spanish citizens for an inflexible policy against ETA  has undermined its credibility. There are reasons to believe that, in the mid-90’s, ETA was already aware that the possibilities to force the Spanish State to give in grew remoter as its operational capacity weakened.
The nationalist front. The third and shortest stage, as it extended over at least two years, was based on the assumption that an alliance with nationalist non-violent forces, founded on their rejection of the autonomic frame in which they had acted so far, would lead to a unilateral progress towards independence that would enjoy a widespread popular support, thus leaving the State no room for response. The strategic change was based on the premise that the terrorist actions of an increasingly weak ETA were not enough to force the State to give in. The new strategy materialized in the contacts between ETA, the PNV[2] and EA[3] in August 1998, in the Lizarra agreements and in the ceasefire announced by ETA in September that same year. But it did not take ETA long to realize that the chances that the nationalist front would lead Basque citizens to give a massive support  to an immediate independence process were poor; this new strategy could therefore lead to an integration in the autonomic frame of the sectors that supported it. For this reason, ETA broke up with the democratic nationalist forces and resumed its campaign of violence in 2000.
After braking the nationalist front, ETA seemed to have fallen back on the strategy of attrition for some months, but its structural weakness did not take long to show again. As can be seen in the bar chart, terrorist actions have reached in 2002 the lowest level in the last two decades. ETA faces a dilemma, as the strategy of attrition wears out the terrorist group itself, rather than the State and the nationalist front strategy, only possible during a ceasefire, made it necessary to give the leadership in the independence process over to the democratic nationalism, while ETA limited itself to a marginal role.

The organic network of ETA
In the last years judicial proceedings are affording an increasingly accurate image of  the network headed by ETA. The examining judge Baltasar Garzón of the Audiencia Nacional (National Criminal Court), in a important order issued 20 November 1998, explained for the first time that ETA was not only an armed organization, but the apex of a whole movement that followed its guidelines, and that it was organized around an illicit structure created in 1975 and known as Koordinadora Abertzale Sozialista (KAS). When they were confronted with the possibility of being accused of unlawful assembly, KAS decided to dissolve in 1998, and next year the group Ekin appeared  with a similar function.
The changes of name have not hampered the progress of the investigations that have led Judge Garzón to prosecute the leaders of several structures that make up the network of ETA, successively outlawed. The main elements in this complex were Ekin itself, outlawed in March 2001; Xaki, an organization that acted as a representative of ETA abroad, banned in March 2001; the youth wing Haika, a merger of the Spanish-Basque Jarrai and the French-Basque Gazteriak, afterwards given the name of Segi, that has played an important role in the incitement of street violence, and was banned in May 2001; the organization Gestoras pro Amnistía, in charge of the control and coordination of ETA prisoners, that afterwards was given the name of Askatasuna and was banned in December 2001; and finally Batasuna, the political party formerly known as Herri Batasuna, the political wing of ETA. In the summer of 2002 both the Spanish Parliament and the Audiencia Nacional initiated a process to ban Batasuna; the Parliament has passed a new law on political parties that allows the outlawing of parties deemed to support terrorism. And Judge Garzón, in the light of the evidence collected for years, has decreed the preventive suspension of Batasuna and prosecuted its leaders, accused of being part of ‘the terrorist complex headed by ETA’.
These structures fulfilled a large number of criminal tasks, such as the funding of ETA, the support to its cells, the dissemination of orders, or even violent actions that have been defined by some analysts as low-intensity terrorism. We will highlight at least this last aspect.
In the mid-80’s ETA compensated part of its operational weakness with the mobilization of its sympathizers who were part of the organization Jarrai. Jarrai militants were at the centre of a wave of street violence mainly aimed at material targets such as banks, offices of political parties opposed to ETA, or public transport vehicles, but also at people, thus spreading fear (‘socialization of suffering’, according to ETA’s terminology). This was known as kale borroka (street fight), and it was a breeding ground for a large number of the terrorists who have recently joined ETA cells.

The upsurge of the kale borroka, that reached a height in the years 1995 to 1997 and did not stop during the ceasefire, is partly a result of the feeling of impunity among those who were involved in it. The legal reform undertaken in 2000 brought about changes in the situation, as the penalties  established for this type of criminal acts were toughened, but  it is generally felt that it has been mainly the process leading to the banning of Batasuna that has conveyed the milieu of ETA the clear message that impunity has come to an end. This can be inferred from a quarterly analysis of kale borroka attacks in the last years, as the following bar chart shows.
The banning process of Batasuna is still in progress and its outcome cannot be foreseen; however, it is clear that the long period in which ETA cells could kill while the organizations that made up its network acted in broad daylight, thus multiplying the intimidating effect of the attacks, has finally come to an end. For twenty-five years these organizations had provided ETA a wide social base; without it a terrorist organization can hardly become a serious threat.
The growing rejection of ETA in Basque society
The votes attracted by Herri Batasuna (HB), the party that in 1998 changed its name for Euskal Herritarrok (EH) and that is known nowadays as Batasuna, are the most reliable indicator of the social support received by ETA, although it must be born in mind that part of the voters are against terrorist violence. The results obtained by HB/EH in the elections to the parliament of the Basque Autonomous Region (CAV), shown in the bar chart below, have constituted for twenty years about 10% of the electoral roll, i.e. about 150,000 voters. The fluctuations have not been remarkable, but they are significant enough. In the first place, an increase can be observed from 1984 to 1986, which was probably related to the activities of the GAL. A gradual decrease started ever since that has only been interrupted in 1998, undoubtedly due to the ceasefire and to the nationalist agreement of Lizarra. Euskal Herritarrok obtained the highest number of votes (223,264) in 1998, whereas the 143,139 votes obtained in 2001 were an all-time minimum. There is a hard core made up of 150,000 persons loyal to the political wing of ETA, but its body of electors is not monolithic, as they share the aims of the terrorist group to a larger extent than its methods.

However, in order to understand the complex relation between ETA and Basque society we cannot confine ourselves to HB voters. We must take into account the huge success ETA enjoyed in the final years of the Franco dictatorship and in the early years of the transition to democracy, when they engaged in an action-repression-action  spiral or, in other words, the harmful effect on the legitimacy of the State that the often indiscriminate repressive measures taken in the fight against ETA had in the eyes of Basque society. The principle enunciated by Max Weber that the State is characterized by the monopoly over the legitimate means of coercion was no longer effective in the Basque Country in the first years of the transition. An opinion poll conducted in 1980 by Francisco Llera proved that the loss of legitimacy suffered by the State was evidenced by the voters of most Basque parties. As can be seen in the bar chart below, UCD[4] was the only party that managed to take root in the Basque Country, whose voters did not agree with the statement that ‘state violence’  (arrests, police repression, restrictions on the freedom of speech etc.) is more important and more serious than terrorist attacks).
During the transition period, UCD governments restored democracy, released all ETA prisoners, and promoted the adoption of the Basque Autonomy Statute, but it did not suffice to eradicate the hostility towards the State that had bred in the previous years and that was nourished by the repressive measures that were still taken.  In those circumstances, the new climate of freedom favoured the activities of ETA and its supporting organizations. The situation changed in the 80’s in spite of the negative impact of the attacks carried out by the GAL. The establishment of autonomic governments, the development of a democratic anti-terrorist policy that excluded indiscriminate repression, the anti-terrorist pact of Ajuria Enea, endorsed in 1988 by all Basque political parties, the gradual awakening of a Basque pacifist movement that gathered momentum with the social response to the kidnapping of the Guipúzcoan businessman Julio Iglesias in 1993… factors  like these gave legitimacy back to the State and took it away from ETA.
The impaired image of ETA activists is reflected by opinion polls. The bar chart below shows only the most favourable answers given by those who regard ETA terrorists as patriots or idealists, and the most unfavourable, given by those who regard them as fools, criminals, murderers or simply terrorists. The contrast between the transition years and the 90’s could not be clearer, and it shows the growing rejection of ETA. The results for 1999 show, however, that ETA declared a ceasefire in order to improve the image of its activists. This question has not been repeated in any subsequent opinion poll.
The attitude of Basque society towards ETA itself can be monitored from 1981 by means of the Euskobarómetro conducted by the Department of Political Science of the University of the Basque Country (UPV). The bar chart below shows the most favourable answers, an expression of unconditional support  or a critical justification, and the most hostile, an expression of outright rejection. As in the case of the questions on the image of ETA militants, there is a general trend towards a growing rejection of ETA with two significant  drops: in 1987, probably as a response to the GAL, and in 1999, due to the ceasefire. This series proves that after the ceasefire the support to ETA has plunged to an all-time minimum. At the beginning of the 80’s about ten out of one hundred Basques gave an unconditional or a qualified support to ETA, whereas in 2002 only two or three out of one hundred.
This widespread rejection of ETA, shared by three out of every five Basques, goes beyond the dividing line between nationalists and non-nationalists. It is important to point out that there are not two different communities in Euskadi, one that considers itself Basque, and one that considers itself Spanish, but a range of identity-related attitudes and a majority that considers itself Basque and Spanish at the same time. According to the last opinion poll conducted in October 2002 by the Office for Sociological Research of the Basque Government, 31% of the Basques consider themselves only Basque, 16% rather Basque than Spanish, 36% equally Basque and Spanish, 5 % rather Spanish than Basque, and 6 % only Spanish (Sociómetro Vasco, 20). The results obtained in all the opinion polls conducted since 1995 are identical (Avilés 2002).
Likewise, there is no clear division as regards independence, which is the target not only of ETA but also of a large part of the democratic nationalist movement. Opinion polls conducted by the Basque Government show that one out of four citizens are in favour of independence and one out of three against it, and that the percentage of don’t knows is very high. The following bar chart shows how the percentage of citizens that declare themselves to be against independence is on the rise. According to the last opinion poll, 54% of the nationalist citizens are in favour of independence and 8% against it, whereas, as regards non-nationalists, 10% are in favour and 48% against.
On the other hand, although most nationalists share with non-nationalists the rejection of ETA, their opinions on how to combat it tend to differ.  According to the last opinion poll conducted by Euskobarómetro, 31% of non-nationalists agree that terrorists should serve full sentences, an attitude that is shared only by 8% of the nationalists. And as regards the move to ban Batasuna, 46% of the non-nationalists consider it wise, and only 7% of the non-nationalists. To be accurate, 85% of Basque PP[5] voters and 66% of PSOE[6] voters deemed it wise, whereas 100% of EH voters, 73% of PNV and EA voters and 59% of IU[7] voters considered it wrong (Euskobarómetro 2002).
The sociological surveys conducted periodically by the Basque government show that there is a growing rejection of terrorism also among Basque youth. In 1986, 36% of the people polled, with ages ranging from 15 to 29, justified terrorism in certain circumstances, 27% in 1990 and only 9% in 2000. The survey carried out by Javier Elzo in 1990 is particularly interesting, as it offers a highly detailed characterization of the young Basques who justify terrorism. The following bar chart gathers some data from the survey, from which we can concluded that boys support terrorism more than girls, cannabis consumers more than those who avoid drugs, those who consider themselves exclusively Basque more than those who consider themselves equally Basque and Spanish, and  non-practising more than practising Catholics.
This information can be complemented by the data contained in a report made in 1999 on a national basis, in which Elzo himself proposes a typology of young people based on their values (Elzo 1999). By means of a sophisticated system of statistics, the young people polled were sorted out, so that five different types of young people emerged. We are interested in the so-called anti-institutional, that represent only 5% of young Spaniards, but 77% of Batasuna supporters. The values of these anti-institutional young people are characterized by their tendency to justify terrorism and street vandalism, their lack of confidence in the institutions, their feeble interest in work, family and studies, their lack of fondness for sports, for TV programmes and for computers, and a stronger disposition to justify drunkenness, the failure to pay in public transports, drug abuse, extramarital affairs and night noise. To sum up, it is the typical profile of a young transgressor, present in every society, but there is something peculiar to the Basque Country in that these young people are to a large extent the breeding ground for the kale borroka.
A report on juvenile violence sponsored by the Basque Government in 2001 offers more information on the main figures in the kale borroka. According to this survey, 8.1% of young Basques declare themselves to be ‘willing to participate in real street riots involving assaults on persons, property and personal belongings’ (Ruiz de Olabuénaga 2002). Finally, we should add that, according to a recent statement by the Minister of the Interior of the Basque Government, Javier Balza, more than three hundred young men and women have left their permanent residence as a result of the recent operations against street violence activists, which implies that they were involved in it. These young people who run away after they have taken part in violent activities are frequently recruited by ETA, but Balza himself rules out the possibility that all of them join the terrorist group, which, among other things, lacks the means to incorporate new activists (Avui 29/12/2002). However, we should bear in mind that the breeding ground for ETA has not been depleted.
Anti-terrorist fight and international cooperation
As we have previously pointed out, the successes of past years in the fight against terrorism are partly due to the loss of social support experienced by ETA, which makes it increasingly difficult for them to find substitutes for the arrested activists; partly to a policy that has avoided the two conflicting mistakes made in the past (indiscriminate repression and the apparent impunity of the organizations that support ETA in its terrorist activities); and partly to an enhancement of international cooperation.
The importance of cooperation with France can be seen in the bar chart below, that shows the high number of ETA terrorists arrested in the last years in the neighbouring country. For instance, 191 members of ETA were arrested in 2002, 122 in Spain, 63 in France and 6 in other countries.
The high number of arrests made in both countries after the end of the ceasefire has caused severe harm to ETA, both from a quantitative and from a qualitative point of view. In the course of the last three years 34 ETA cells have been dismantled only in Spain (MIR 2002), losses the terrorist group is unable to replace at the same rate. That is the reason why ETA  is increasingly forced to resort to inexperienced activists  or to well-known veterans, who are arrested after an increasingly shorter period of terrorist activity. The result is a loss of operational capacity that shows in the smaller number of attacks.
Should we wish to find an indicator of the decline of ETA, imperfect, no doubt, and yet meaningful, we only have to work out the ratio between the number of attacks carried out each year, which reveals its operational capacity, and the number of arrests, which shows the decline of that capacity. The ratio between both figures is shown in the following bar chart, in which we can see that the year 1992 was a catastrophe to ETA, as the leading members of the terrorist group were arrested in France; this was followed by a slight recovery and by a sharp decline in the last three years.
Benjamin Franklin pointed out once that a country that sacrifices freedom in order to strengthen security, ends up having neither freedom nor security. Spaniards have not fallen into the trap. For twenty five years they have fought a battle against one of the most dangerous terrorist groups in the history of Europe, without sacrificing civil liberties in any way. On the contrary, it has been the brutality of ETA and its milieu that has significantly restricted the liberties of many Basque citizens, especially of the non-nationalist half of the population.
Many mistakes have been made in the course of this long battle, when democratic principles were abandoned in the interest of a presumed efficiency , either by resorting to the ‘dirty war’ or by granting portions of immunity to ETA collaborators. But the ‘dirty war’ was ruled out fifteen years ago, and recently an important step has been taken towards the end of impunity with the banning process of Batasuna.
Spanish experience proves that, once a terrorist movement takes root, it can only be weeded out by means of a strenuous effort, in which there is no place for measures opposed to Democracy. We Spaniards have made that strenuous effort and now we are close to our target: to give back to Basque citizens the possibility to fully enjoy freedom and security, long threatened by a terrorist group.
Recommended reading
AVILÉS, Juan (2002): 'Identidad nacional y actitudes ante el terrorismo en la Comunidad Autónoma Vasca'. www.
DOMÍNGUEZ IRIBARREN, Florencio (1998a): ETA: estrategia organizativa y actuaciones, 1978-1992. Bilbao, Universidad del País Vasco.
DOMÍNGUEZ IRIBARREN, Florencio (1998b): De la negociación a la tregua, ¿el final de ETA? Madrid, Taurus.
ELORZA, Antonio, ed. (2000), La historia de ETA. Barcelona, Planeta.
ELZO, Javier, dir. (1990): Jóvenes vascos 1990. Vitoria-Gasteiz, Gobierno Vasco.
ELZO, Javier y otros (1999): Jóvenes españoles 99. Madrid, SM.
Euskobarómetro (Departamento de Ciencia Política de la Universidad dl País Vasco).
GARMENDÍA, José María (1979-1980): Historia de ETA. San Sebastián, Aramburu.
GRANJA, José Luis de la y PABLO, Santiago de (2000): 'La encrucijada vasca: entre Ermua y Estella', en Tusell, Javier (dir.): El gobierno de Aznar: balance de una gestión, 1996-2000. Barcelona, Crítica.
JÁUREGUI, Gurutz (1981): Ideología y estrategia de ETA: análisis de su evolución entre 1959 y 1968. Madrid, Siglo XXI.
LINZ, Juan José (1986): Conflicto en Euskadi. Madrid,  Espasa Calpe.
LLERA, Francisco José (1994): Los vascos y la política. Bilbao, Universidad del País Vasco.
MIR (Ministerio del Interior): “Balance 2002”.
MORÁN, Sagrario (2002): 'La cooperación antiterrorista: el eje Madrid-París', en González Calleja, Eduardo:  Políticas del miedo: un balance del terrorismo en Europa, Madrid, Biblioteca Nueva.
REINARES, Fernando (1990): “Sociogénesis y evolución del terrorismo en España”. En S. Giner, ed. : España: sociedad y política, Madrid, Espasa Calpe.
REINARES, Fernando (2001): Patriotas de la muerte: quiénes han militado en ETA y por qué. Madrid, Taurus.
RUIZ DE OLABUÉNAGA, José Ignacio y otros (2000): Juventud vasca 2000. Vitoria-Gasteiz, Gobierno Vasco
SÁNCHEZ-CUENCA, Ignacio (2001): , ETA contra el Estado: las estrategias del terrorismo, Barcelona, Tusquets
Sociómetro Vasco (Gabinete de Prospección Sociológica del Gobierno Vasco).
SULLIVAN, J. (1988): El nacionalismo vasco radical, 1959-1986. Madrid, Alianza Editorial. 
WOODSWORTH, Paddy (2002): Guerra sucia, manos limpias: ETA, el GAL y la democracia española. Madrid, Crítica.

[1] N. del T.: Grupos Antiterroristas de Liberación - Anti-terrorist liberation groups
[2] N. del T.: Partido Nacionalista Vasco - Basque right-wing nationalist party
[3] N. del T.: Eusko Alkartasuna - Basque nationalist party, split off from PNV
[4] N. del T.: Unión de Centro Democrático - centre-right party
[5] N. del T.: Partido Popular - ruling centre-right party
[6] N. del T.: Partido Socialista Obrero Español - Spanish socialist party
[7] N. del T.: Izquierda Unida - Spanish coalition of left-wing parties