Now we know who - why?

The London bombings were carried out by British men from West Yorkshire. But why did they do it?
No one has convincingly claimed responsibility - no group, cause or organisation. We keep on assuming that it was Islamic extremists or Al Qaeda or even Hamas or a combination of these factions. The attacks may bear their hallmarks but why do we assume we know? And what is their demand? Do they want us to pull out of Iraq, become Islaamic, stop supporting the United States or Israel or another power in the world? There is no message with this attack, no ultimatum, no conditions, no apparent deal or terms. Until we know what's demanded the bombing has become the rallying point for any campaign that can hang a cause on it. Ditch the US, get rid of Tony Blair and New Labour, pull out of Iraq, stop supporting Israel, give Afghanistan back to the Taliban, end immigration, and so the list goes on.
True terror is when people are killed without a cause. Killing for its own sake. The threat of more to be indisciminately visited on the innocent is made even more terrifying for want of a remedy. Not that for a moment any society should give in to the demands of terrorists, not knowing what those demands are somehow adds to the mindlessness of it all.
There can be only one judgment made at this stage. Deliberately killing people like this is totally unjustified and wrong. And whoever poisoned the minds of the young men who died with their bombs must be tracked down and brought to justice.