Saturday night’s attack in London lasted only a few minutes but it left seven people dead, along with three suspected attackers, dozens injured and a city terrified. Unlike the Manchester Arena bombing less than two weeks ago, the attack in London was low-tech, using a van to mow down pedestrians on London Bridge, before its three occupants leapt out carrying long knives.
The three assailants, who wore fake explosive belts, went on a rampage through the streets around Borough Market, a busy area full of restaurants and bars, stabbing people at random. The police response was immediate and lethal, and the three attackers were shot dead within eight minutes of the first emergency call as the attack began.
The authorities can draw some comfort, and the public some reassurance, from the speed and effectiveness of the emergency response to Saturday’s attack and the similar attack at Westminster Bridge 10 weeks ago. But for the third time in as many months, terrorists have slipped through the security services’ net of human intelligence and electronic surveillance.
The Westminster attack was the work of a single attacker who operated entirely alone but the Manchester bomber was part of a network and Saturday’s attack involved at least three people. MI5’s 4,000 staff have identified 3,000 people in Britain they regard as dangerous Islamists and the agency is investigating 500 possible terror plots.
There is a broader pool of 20,000 people who are not regarded as an immediate danger but, like the Manchester bomber Salman Abedi, could become one. The security services do not have the resources to keep so many people under close surveillance, although some experts believe that increased use of artificial intelligence could help to identify suspicious patterns of behaviour.
Theresa May on Sunday said there was too much tolerance of extremism in Britain and that it had to be stamped out. And she proposed a review of counter-terrorism legislation, floating the possibility of tougher custodial sentences for "apparently less serious" terrorist offences.
Islamic State
A key element of Britain’s counter-terrorism strategy is Prevent, a programme designed to identify people who may be at risk of radicalisation. The programme is unpopular within Muslim communities, partly because it can bring under the scrutiny of the criminal justice system people who have not yet been radicalised.
The latest attacks will increase pressure to reform Prevent, perhaps by developing a kind of probation system for more dangerous offenders or suspects but taking the preventative, early intervention programmes out of the criminal justice system altogether.
Saturday's attack, using a vehicle and knives, mimicked atrocities in Nice, Berlin and Stockholm which were inspired by Islamic State. The terror group, which once boasted that it was creating a caliphate in Iraq and Syria, is months away from territorial extinction, as it is driven from its Iraqi stronghold of Mosul and its Syrian base at Raqqa.
As it ceases to be a territorial power, Islamic State is returning to its earlier role as a guerrilla organisation in the Middle East. But its leaders have called on supporters in Europe and elsewhere to launch low-tech attacks such as Saturday's in an effort to strike fear into the populations of its western enemies.
The London attack has prompted renewed calls for tougher legislation to allow the authorities to apprehend suspected terrorists before they carry out an attack. Former Conservative leader Iain Duncan Smith said on Sunday that the government was not considering the introduction of internment without trial. But he suggested there could be a toughening of Terrorism, Prevention and Investigation Measures (Tpims) which place restrictions on suspects who have not been convicted of any crime.