Everyone else is commenting on the bombing in Spain. If I know my terrorist groups, (I may be quite off base, but bear with me) it’s not ETA’s usual style. As far as I can tell, their attacks were usually aimed at police forces. They’d plant a bomb, call it in, wait for the civilians to evacuate the area, and then detonate it when the police arrived to defuse it. This is the attack of a group which feels it has no friends left in mainstream society, which is attacking society itself.
ETA may have lost all moderate allies when concessions were made over autonomy, and now is reduced to a smaller, more radical core that simply wants to attack Spain’s hegemony, civilian sympathy be damned. Or it could be the work of another group trying to tear down Spanish society; the knee-jerk guess there is radical islamists, since the other major foes of the West per se, communism and anarchism, are not quite the forces they were.
I don’t imagine it could have been Catalan separatists; they’re not quite so violent or extreme, and seem to be getting what they want within the national framework. I could see them having a concerted letter-writing campaign and some very noisy protests, and maybe a ballot initiative or a tax revolt. But not a terrorist campaign.
It had really begun to feel like Spain was almost totally recovered from the consequences of the Spanish Civil War, and of Franco’s repression of linguistic and ethnic minorities. Maybe it has, and this is a completely new problem. But I doubt it.