Chris Albritton, writing in his blog, Back to Iraq, believes there’s reason to consider that the Madrid train bombing might be a joint operation:
There’s no reason that al Qaeda wouldn’t work with — or help fund — groups that further its own ends in the short run. (Which is why it never worked with Saddam. Not only did it not share any long-term goals with Iraq, and in fact wanted to destroy Saddam’s government, but it didn’t share any short-term goals either. Saddam didn’t want to destroy the United States. He wanted an end to sanctions so he could go back to trying to dominate the Middle East — something bin Laden wants to do himself.)
So. What conclusions may be drawn? As Juan Cole notes, if the ETA did it, it would be seen as local significance and probably bolster the standing of Jose Aznar’s conservative party prior to the Sunday ballot. If it’s jihadists, this will be seen as on par with Sept. 11, 2001, Bali and Lockerbie — and the War on Terror will have suffered a setback. The U.S., paradoxically, probably would like to have the bombers come from al Qaeda because that would bolster Bush’s charge that the War on Terror is ongoing — so don’t change commanders in the middle of a war.
However, either/or is too limiting. I think this was probably some kind of joint venture between the ETA and jihadists, but, still, I wouldn’t be a bit surprised to see this as a wholly Islamist enterprise. We just don’t know the full story yet.
As Chris points out, it is too early to know but this is an interesting insight that the mainstream media, to my knowledge, has not written about.
Update: I was wrong. BBC is speculating about collaboration.