There is a natural reluctance to link terror attacks, which should draw people of all persuasions together, to general elections, in which politicians and parties must differ – always robustly, sometimes fiercely.  Yesterday’s murder of six innocent people by terrorists suddenly puts the knockabout business of electioneering into perspective: the last looks small as it pauses today in the shadow of murder.  It seems wrong to put yesterday evening’s horrifying attack in London and Thursday’s poll across the whole country into the same sentence.

Or, rather, it would do, were it not that the London atrocity follows the Manchester horror.  Less than a fortnight ago, teenage girls were targeted by a suicide bomber.  Twenty-two people were killed and 160 injured.  As we write, the identity of the three terrorists were who targeted London Bridge and Borough Market is not known.  Nor is it clear whether or not they had support from a larger cell.  But it is surely no coindence that two mass assaults on innocent people have been unleashed since this election campaign began.  There may be more before it ends. Furthermore, Ramadan is happening – and it is a preferred season for Islamist terror attacks.

This is not to argue that ISIS or Al Qaeda want a particular outcome.  But it is to claim that they want to destabilise our liberal democracy at one of the moments in its workings when it is most on public display.  Islamist terrorists have form: in 2004, they targeted Spain’s general election, killing almost 200 people and injuring around 2000 in the Madrid train bombings.  The atrocities were followed by Jose Maria Aznar and the Popular Party being swept out of government.  The aim of terrorists is to create fear, panic, chaos – and the terror from which they take their name.  The objective of Islamist ones is to do so as part of what they believe to be a holy war.

As we publish, yesterday’s attack looks less like those Spanish bombings, or even the Manchester one, than the kind of rolling assaults that we have seen in Paris and Mumbai, whereby a gang comes to kill and be killed.  Some may find it reassuring that this particular one does not appear to have been armed with automatic weapons.  They will also draw comfort from police claims that three terrorists were shot dead within eight minutes of the attack begining.  None the less, there appears to have been no advance intelligence of the assault and the police, as the horror raged on, tweeted “run, hide, tell” – the procedure for a mass assault – for the first time in Britain.

You may or may not agree that the Islamists who drove cars at innocents, and reportedly slashed at them with knives, were targeting this week’s election – as well as anyone they could find on London Bridge and in Borough Market.  However, it is now beyond dispute that Britain is no longer an exception – insulated by superior community relations and better policing work from the kind of mass murders seen in France and Belgium.  March’s Westminster Bridge attack was a sign that twelve lucky years were coming to an end.  Manchester two weeks ago and London last night confirmed it.

The security services have consistently warned that 7/7 would eventually be followed by further successful attacks.  They were right.  It was also inevitable that terrorists would target London, the home of Britian’s political and media elites.  (The offices of News UK, the successor of News International, are in London Bridge Street.)  They understand well that news of murder in the capital will hit these harder than news of murder in Manchester: doubtless it shouldn’t, but it will.  And it is evident that no present restriction on guns nor future crackdown on knives could guarantee safety: as we have discovered, terrorists can simply run amok with cars instead.

There are three main possible security responses to the threat, and to the recent killings.  The first is to stick to the present strategy: that’s to say, beefing up the security service and police capability, so that it seeks to cover more of the 23,000 “subjects of interest”, recruiting what this site calls an army of spies and informers.  A merit of this approach is that it comprehends the scale of the challenge, and appreciates that there is no easy answer to the menace of Islamist terror – a threat as alarming, in its own distinctive way, not only to the traditional, classical Islam, but to the children of Britain’s Muslim majority, who it aims to recruit.

But it will not satisfy voters indefinitely if mass attacks continue and intensify.  It is not impossible to imagine them reaching a point at which offers of hospitality to those stranded overnight, hashtags of defiance, floral tributes, poems, mass rallies and self-deprecating jokes are not enough, together with deserved tributes to the police and emergency services.  To say so is not to criticise any of these reflexes.  ConservativeHome reads them less as signs of complacency than evidence of knowingness – of a deep, intuitive, unarticulated understanding that the struggle against Islamist extremism is likely to last at least as long as that against communism.

The second option is what we might call Arrest and Intern.  Control orders, banging suspects up in Belmarsh, and TPIMs are varitants of this approach.  The first and the third have been proved to be vulnerable: forms of house arrest and tagging are no security substitute for prison.  And like the second, they have proved vulnerable to British judges applying the norms of the ECHR and Human Rights Act.  For this reason, Theresa May wanted to leave the European Court as recently as last summer.  Fear of the effects of doing so on Scotland and Northern Ireland drove her off that position.  Downing Street is chary of tipping opinion north of the border towards independence.

But even if the ECHR could be magicked away, and a British Bill of Rights cast so as to offer terrorists no legal bolt-holes, the arrest and intern option is problematic.  Our only recent experiment with internment, in Northern Ireland in the 1970s, did not end well.  There are practical questions, such as where and how one would accomodate thousands of suspects.  There are moral ones about depriving people of their liberty on what may be no more than hearsay or suspicion.  And there are political ones about whether mass arrest would simply serve as a recruiting sergeant for more terror, thus making the threat to security worse than before.

This site’s sense is that there is no public consensus for such a leap in the dark – yet, anyway.  The third option is Bug and Charge.  It would be founded on sweeping away restrictions on the availability of intercept evidence in court.  This was the approach of the Party when it was in opposition.  It has foundered on opposition from the security services and police, based on their view of the adversarial nature of our legal system, and its possible consequences.  But it would allow more suspects to be charged and convicted.  Some Ministers claim that it would march in step with a warrant system aimed at requiring those who hold the data of suspects to disclose records.

This could be a workable alternative to foolish notions of breaking encryption.  Bug and charge would also avoid the clash with Parliament and the courts that attempting to breach the ECHR would bring with it.  And it would begin to address the scandal of terrorists from Syria wafting back into the county on British passports.  The response of Official Britain to this latest assault seems to be: suspend campaigning and discourage debate.  This is the wrong way round.  Campaigning should resume as possible, and security options should be probed.