Who could have been responsible for the bomb blasts at three Madrid railway stations which have killed over 190 innocent civilians?
ETA, the Basque separatist organisation, or the International Islamic Front formed by Osama bin Laden in 1998 and presently co-ordinated by the Lashkar-e-Tayiba of Pakistan? The Lashkar has sleeper cells in the UK, which could operate anywhere in Europe.
The timing of the blasts just before the general election in Spain points the needle of suspicion at ETA, which had used improvised explosive devices effectively in the past and had not hesitated to target innocent civilians -- for example, in the June 1987 attack at a Barcelona supermarket which killed 21 shoppers.
It has been reported that while openly blaming the ETA for the Madrid explosions, the Spanish authorities have not ruled out the possibility of this being a reprisal attack by jihadi terrorist elements for the Spanish government's support to the US and UK for their invasion and occupation of Iraq and for sending Spanish troops to Iraq, which were the target of attacks by International Islamic Front elements last year, resulting in fatal casualties.
ETA itself has not so far claimed responsibility for the blasts. While it is a ruthless organisation, it had not come to notice for such co-ordinated attacks, which must have involved the use of large quantities of explosives, more than the ETA was known to have access to.
Madrid has a large number of immigrants of Moroccan origin, many of them sympathetic to bin Laden and Al Qaeda. Moroccan components of Al Qaeda and the International Islamic Front participated in some terrorist strikes, the last of them in Casablanca in Morocco last year. Apart from Spain's role in Iraq, its close co-operation with the US in the hunt for Al Qaeda agents has also earned it the wrath of Al Qaeda and the International Islamic Front.
Other countries too have been targeted by bin Laden -- the UK, France, Italy, Germany, Australia and West Asian countries co-operating with the US. Why should they choose Spain at the present moment?
Most probably because there were gaps in physical security there and any terrorist would be tempted to take advantage of such gaps.
These are still speculative theories at present. One has to await concrete evidence before coming to a definitive conclusion.
Photograph: Pierre Philippe Marcou/AFP/Getty Images