Maybe the idea was to damage the governing conservatives in next week's election, but it's likely to have the opposite effect. I'd think the first reaction of most Spaniards will be to back up whichever party is going to come down hardest on the perpetrators.
Q20. Why has there been all this trouble in the Basque Country?
A20. That's a long story. Throughout the Middle Ages, the Basque provinces, north and south, were largely self-governing, and they had a vigorous tradition of local democracy. Over time, of course, Basque autonomy came under increasing pressure from Paris and Madrid. In the north, Basque rights were abruptly swept away by the French Revolution. In the south, autonomy lasted longer, but in the 19th century it came under attack from centralist governments in Madrid, leading to major civil wars on two occasions and to the enforced removal of the traditional Basque rights.
From the late 19th century, the Spanish Basques, fearing for their language and their culture, began pressing for reforms and for greater autonomy. This strictly peaceful campaign was interrupted by the installation of a right-wing dictatorship in Spain in the 1930s, but regained its momentum after the restoration of democracy. But then a military coup in 1936 led to the Spanish Civil War and to the establishment of a brutal Fascist dictatorship in Spain under General Franco. The Basques, who had fought against the Fascists during the war, suffered terribly during the war and under the subsequent Fascist oppression: quite apart from the death and destruction caused by the war itself (including the deliberate destruction of two Basque cities by Hitler's air force), the Basques found themselves singled out for particular vengeance by Franco. Basque soldiers and politicians who had not managed to flee into exile were imprisoned, condemned to forced labor, tortured, and often shot; all outward signs of Basque identity were prohibited, and the very speaking of Basque was declared illegal.
Permitted no legal voice, the Basques gradually began to organize clandestinely to discuss what might be done. A student discussion group founded in 1953 and originally called EKIN changed its name in 1959 to ETA and began to contemplate more active resistance. At first ETA was in no way violent, but every attempt at a political gesture was met by savagery from the Spanish police and courts: arbitrary arrests, routine beatings and torture, and long jail sentences. Eventually ETA took the plunge into violence of its own and began assassinating known torturers and murderers among the Spanish authorities. The police reacted with ever greater violence of their own: uniformed police tortured and murdered Basques with complete impunity, death squads composed of off-duty policemen carried out further murders, and there were armed attacks on whole communities described by foreign observers as "police riots".
Faced with such violence, ETA gradually became ever less choosy in its targets, and began gunning for any police or soldiers they could get at. In a technically expert operation which would prove to have far-reaching consequences, ETA managed to assassinate Admiral Luis Carrero Blanco, the anointed heir of the aging Franco. As a result, when Franco finally died in 1975, a democratic government took control in Madrid; elections were held, and the Basque Autonomous Government was set up in 1979, with wide-ranging powers.
This outcome satisfied most people in the Basque Country, and most of the members of ETA quietly left the organization to resume normal lives. But a modest number of hard-core members remained, and continued a program of increasing violence all over Spain, in the hope of obtaining complete independence for the Basque Country. Army officers became favorite targets, and bombs were placed in popular tourist resorts with the intention of damaging the valuable tourist industry; even the new Basque police force came under attack. The new governments in both Madrid and the Basque Country made vigorous efforts to put a stop to this violence, but so far they have enjoyed only partial success. And that's where things stand today.
I feel that the Basque separatists would not do this kind of work since it would defeat their purpose immediately. It would be a stupid move and they are not stupid.