From UPI:

While all fingers in Spain are pointing at the Basque separatist movement ETA as the perpetrators of Thursday's atrocious train bombings that left some 186 dead and 600 wounded, the attacks carry all the markings of al-Qaida and its jihadi affiliates. For starters the Brussels-based World Observatory of Terrorism, an independent think tank affiliated with the European Strategic Intelligence and Security Center, points to five major reasons that cast doubt on the involvement of ETA.

First, ETA generally warns Spanish authorities moments before launching their attacks in which civilians are likely to be harmed. This, obviously, was not the case on Thursday.

Second, ETA traditionally targets representatives of the government or the administration, such as policemen, the military, magistrates or even journalists who oppose them.

Third, ETA customarily selects "symbolic" targets, such as military barracks and administrative buildings. Although ETA's largest attack to date was in 1987 against a supermarket in Barcelona that killed 21 people, this was the exception rather than the norm.

Fourth, ETA always claims its attacks. Following any ETA bombing, ETA militants call in a claim to Spanish authorities. This failed to happen this time.

Fifth, ETA has never in the past carried out multiple attacks. According to some sources, at least 10 bombs were detonated almost simultaneously on Thursday.

On the other hand, these murderous attacks bear the traditional hallmark of al-Qaida: multiple bombs detonating a few seconds apart and programmed to cause the largest possible number of human casualties.