In the wake of the deadly attacks on commuter trains in Madrid, it is still unclear who is responsible. The evidence could point to either the armed Basque separatist group Eta or Islamic militants, and the experts are divided. BBC News Online's Robert Plummer analyses the arguments:
In the immediate aftermath of the blasts, the Spanish authorities had no hesitation in blaming Eta for the bloodshed. On Friday, Spanish Foreign Minister Ana Palacio re-stated the government's stance, saying: "Everything appears to indicate that this terrible carnage is the work of Eta." She acknowledged the possibility that Islamic radicals were behind the attack, saying it was a hypothesis that the government was examining. However, there were "very strong clues, very strong precedents" to indicate it was the work of the Basque separatist group. Looking at the evidence that has emerged so far, those clues and precedents include:
- the material in the bombs was an explosive used in previous Eta attacks
If Eta was responsible, analysts say, the simultaneous attacks mark an unprecedented increase in scale, ruthlessness and co-ordination. Before these bombs, many observers had been tempted to write off Eta as a spent force. Last year, three people died in violent attacks by Basque nationalists - the lowest total for 30 years. There is no doubt that the Spanish government's uncompromising efforts to crush Eta and refuse all political concessions to Basque nationalism have greatly weakened the separatist group. Experts are in sharp disagreement over whether Eta in its current state has the capability to mount such a devastating attack. Sebastian Balfour, professor of contemporary Spanish studies at the London School of Economics, told BBC News Online that high-profile arrests of key leaders had reduced the number of Eta activists to no more than 250. And intelligence analyst Glenmore Trenear-Harvey, interviewed by BBC News 24, said the group would have found it difficult to stage such a co-ordinated effort, given the level of surveillance to which the remaining Eta members are subjected by the Spanish intelligence service. "To organise something with this number of bombs requires an amazing amount of legwork beforehand," he said. But Mia Soar, Europe editor for Jane's Sentinel Security Assessments, believes a crackdown by both the Spanish and French governments might have produced a new and more ruthless Eta leadership. "There have been so many arrests that there has been a constant turn-over of the leadership... they have a lot of young blood at the top. This could explain the new tactics," she told BBC News Online. Another analyst who blames Eta is University of Kiel security expert Joachim Krause. Sebastian Balfour, professor of contemporary Spanish studies at the London School of Economics, told BBC News Online that high-profile arrests of key leaders had reduced the number of Eta activists to no more than 250. And intelligence analyst Glenmore Trenear-Harvey, interviewed by BBC News 24, said the group would have found it difficult to stage such a co-ordinated effort, given the level of surveillance to which the remaining Eta members are subjected by the Spanish intelligence service. "To organise something with this number of bombs requires an amazing amount of legwork beforehand," he said. But Mia Soar, Europe editor for Jane's Sentinel Security Assessments, believes a crackdown by both the Spanish and French governments might have produced a new and more ruthless Eta leadership. "There have been so many arrests that there has been a constant turn-over of the leadership... they have a lot of young blood at the top. This could explain the new tactics," she told BBC News Online. Another analyst who blames Eta is University of Kiel security expert Joachim Krause. BBCSpain.