That London is facing a continuing campaign of terror against its mass transport systems was confirmed by yesterday's four attacks on three tube trains and a bus.
These were more than symbolic attacks, notwithstanding that their scale was qualitatively smaller than those on July 7th in which 56 died. There were four definite explosive devices, all apparently contained in rucksacks. The attacks were co-ordinated in time and the four attackers managed to escape.
This delivers a very worrying message to Londoners and the authorities that there is now an abiding threat to their safety, irrespective of whether those responsible are from the same group which carried out the previous atrocities or others copying them.
These frightening incidents will deepen the debate on security preparedness and intelligence resources which has arisen from the first round of attacks. It is extraordinary that such a provocative attempt should be made during such a high state of alert. And yet an open mass transport system cannot be made as secure as air travel without utterly disrupting its function, London's mayor Ken Livingstone pointed out.
The resilient spirit with which the city's inhabitants have continued their everyday lives was further in evidence yesterday. But there will be mounting demands for more effective security co-ordination as a result. Already the organisation of these services is coming under intense debate, as is the relatively poor intelligence about the presumed domestic sources of such hatred.
Mr Tony Blair has been widely and deservedly admired for the calm leadership he displayed after the July 7th atrocities - characteristics which were also in evidence yesterday. He and leading ministers have insisted that the root of the problem is an evil perversion of the Muslim faith directed by ruthless extremist groups towards vulnerable disaffected youth in Britain and elsewhere. The government has steadfastly refused to relate the attacks in any way to the invasion and war in Iraq, even though security chiefs have warned repeatedly that such attacks are inevitable because of Britain's involvement.
To make this connection is not to make excuses for terrorism or arguments for appeasement. It is to recognise the central political reality that the war has enormously boosted the platform for such extremism. A poll this week showed two-thirds of the British public believe there is such a relationship and even more think there will be further attacks as a result.
These further attacks will intensify the debate on security measures to counter such threats. It is right to concentrate on those who incite hatred and terrorism and to move against organisations promoting them. A civilised society will be able to harness the overwhelming majority of moderate Muslims to this task. And a mature democracy must address the political conditions which give such extremism its dangerous appeal.