What is the lesson of the events in Spain over the last few days? That terrorism is too serious to be used as a party political instrument.

Terrorism has been used by George W. Bush, Tony Blair and José Maria Aznar to legitimise the war in Iraq. The Spanish people, who experienced the reality of terrorism in the terrible explosions last week, refused to accept their arguments.

My own prime minister, Tony Blair, is right when he warns us of the danger of global terrorism. He is right when he says that the terrorists want to create Armageddon. Al-Qaida, in common with all religious fundamentalists, believes in cosmic war, in a life-and-death struggle between good and evil. Al-Qaida militants typically aim at spectacular violence to mobilise recruits to their cause. “The awakening has started,” said Osama bin Laden in a tape after 11 September 2001.

But Blair is wrong when he argues that terrorism justifies the ‘war on terror’. On the contrary, the term ‘war’ feeds into the terrorists’ own conception of jihad. It elevates the terrorists to the status of an enemy, instead of discredited criminals. It implies that military action is justifiable and that the killing of civilians, even if not intended, is somehow legitimate. Many more civilians were killed in Afghanistan and Iraq than have been killed by terrorists in New York, Washington, Bali, Casablanca and elsewhere, and that argument is used, in turn, to justify further acts of terror. The terrorists want war. They want to be bombed because it shows that the cosmic struggle really exists. It adds to the humiliation of young Muslims attracted to the global Islamic cause.

This is the main reason why I opposed the war in Iraq. I do think that most Iraqi people are better off than they were before the war. However, visiting Iraq, I have seen for myself how the method of regime change through invasion is badly suited to democratic development and has left a legacy of violence and state failure that will be difficult to overcome. I opposed the war for three reasons: because innocent people were going to be killed (over 10,000, according to Iraqbodycount.net), because of the damage that was going to be done to international law, and - last but not least - because I feared the war would lead to an increase in terrorism.

There were no links between Saddam Hussein and al-Qaida before the war (although interestingly, western intelligence agencies do not seem to have noted the construction of Wahabbi mosques in Iraq with Saudi money). But the war brought them together. Islamic fighters have joined with the remnants of the Ba’athist regime to stage the ‘resistance’ to the American occupation.

We cannot prove that the war actually increased terrorism. But it is evident that the ‘war on terrorism’ is not working. Explosions in Saudi Arabia, Turkey, Morocco, Moscow, and now Madrid, bear testimony to its failures. (When commentators suggest that al-Qaida targets are mostly symbolic and that trains are unusual, they ignore the explosions on Moscow commuter trains, just as the endless and tragic Chechen war also gets forgotten).

Bush, Blair and Aznar, in their different ways, have used terrorism for their own political purposes. It is perhaps excessively conspiratorial to suggest that Bush used 9/11 to pursue the interests of the military-industrial complex and the neo-conservative agenda. But undoubtedly, the attacks that day turned him into a war president and gave him the popular support he had lacked before.

More recently, Bush has played on that moment and used 11 September in advertisements to support his campaign for election (not re-election because he was never elected in the first place). Blair made his Sedgefield speech in an attempt to draw a veil over the debate about why we went to war in Iraq and (unsuccessfully) to reignite our faith in his moral integrity. And Aznar’s government tried to project the Madrid explosions as the work of ETA.

The Spanish people have shown considerable sophistication. They have seen through these tactics. It would in principle have been easy for them instinctively to rally round their government. They preferred a harder and more thoughtful path.

What is needed now is modesty on the part of politicians. We do not want to be told that they know what to do and have the problem in hand. We know that the threat of terrorism is very real, very complex and very difficult to contain. What is needed is a broad popular discussion about how to deal with terrorism. We have to do the intelligence and policing work. But we also need to understand what attracts young people to the al-Qaida cause.

Al-Qaida is no longer an organisation. It is an idea, which connects a loose network of self-organised groups to be found all over the world, including, and especially, here in Europe. We need to engage in a far-reaching debate among ourselves, and especially among young people, about what is wrong with the world, why so many feel disillusioned and disenfranchised, and why some may seek such drastic nihilistic forms of action. And we need this discussion to be taken seriously. It should not be another ‘consultation’, another ‘big conversation’, another cosmetic attempt to tell us that our politicians are ‘listening’. This is for real and we need to use all the knowledge and reason at our disposal.

The way terrorism is being fought is wrong. Each day there seems to be a new example. The treatment of the recently-released British prisoners at Guantanamo bay cannot be justified in terms of the ‘war on terror’ any more than can the bombing of civilians. Such violations must not be brushed aside or ignored if we are to start to deal with the underlying causes of terrorism. To do so risks increasing the political marginalisation felt so keenly by those who opposed the war and checking the public mobilisation and deliberation that is essential if we are to deal with terrorism from its roots.