The Observer view on the Manchester bombing | Observer editorial

Last week’s terrorist attack at the Manchester Arena has left the country reeling. The days that followed have been rightly reserved for grieving for the victims, so many of them children, for reflection and tribute and for a coming together in a city that has displayed resilience, strength and compassion in the face of tragedy.

But it is also right that, as the election campaign shifts into gear again, there is proper scrutiny of the effectiveness of the government’s approach to counter-terrorism. In the wake of any terrorist incident, the most immediate questions raised are about surveillance: was the perpetrator known to the security services? If so, why were they not under the kind of surveillance that could have prevented the attack? In the weeks to come, our security services will face difficult questions as to why Salman Abedi, the Manchester bomber, was not a current focus of investigation, given that he was known to them. Was it a decision justified on the basis of intelligence?

It is important to acknowledge, however, that it would be impossible for the security services to keep everyone who poses a threat under surveillance, given how resource-intensive this would be. It has emerged that the security services have more than 20,000 people associated with Islamic extremism on their radar, with 3,000 under surveillance or investigation. Many will have been born in Britain, lured by the marked increase in the volume and accessibility of extremist propaganda we have seen.

Labour has been right to warn in recent months that public spending cuts have affected the robustness of counter-terrorism operations. While funding for counter-terrorism policing has increased, community policing has suffered significant cuts: there are almost 20,000 fewer police officers in England and Wales than there were in 2009. The police inspectorate has reported that cuts have left the police force in a “potentially perilous state”. Ministers have disingenuously claimed that cuts to frontline policing are irrelevant to counter-terrorism, but community police officers, who can build trusted relationships with local communities, are a vital part of any intelligence-gathering operation.

Last year, an independent report into extremism in the prison system found a growing problem with radicalisation, but no adequate strategy to combat it. Cuts to the prison estate mean the number of prison officers has fallen by a third, making prison a far more dangerous place.

Labour has provided robust opposition in both these areas. But boosting community policing or the prison service is not enough to counter extremism. The most controversial part of the government’s counter-terrorism strategy is its Prevent strand, which aims to stop people from being radicalised in the first place. Those believed to be at risk of being drawn into terrorism can be referred – by parents, teachers or community groups – to multi-agency panels, who can put in place a tailored package of support for that young person.

There are a number of issues with the government’s approach: there is little transparency about criteria for success or the programme’s effectiveness and no effort is being made to build knowledge about what works, given the lack of evidence. It is right that schools have a statutory safeguarding duty in relation to grooming for terrorism, in the same way as they do for child sex abuse, but there has been far too little training of teachers on how to exercise it.

However, much of the critique levelled at Prevent by some on the liberal left and in some Muslim communities is unfair. Those calling for it to be scrapped never say what should replace it. Those calling for it to be rebranded fail to understand its perceived toxicity stems less from its brand and more from opposition to the very concept of preventing terrorism by targeting those in the early stages of radicalisation. Those who argue that it is an Orwellian spying programme ignore the fact that participation is voluntary and requires parental consent. Those who say it unfairly targets Muslims fail to acknowledge that any programme aimed at preventing radicalisation will, by its very nature, include a disproportionate number of referrals associated with Islamic extremism, given the scale of the issue in the UK.

This is not the only issue with the left’s response to terrorism. Jeremy Corbyn’s decision to put British foreign policy at the heart of his speech on countering terrorism was unsurprising, given the positions he has taken in the past. The argument he advanced, that there is a connection between British intervention in the Middle East and the terrorism of Islamic State, is undeniable. However, Corbyn’s critics are also right when they point out that Islamist fundamentalism predates western intervention in Iraq and that the unspeakable evils of Isis are felt most not in the west but by its victims in the Middle East, unassociated with western intervention. But, as many have acknowledged, there is a connection between the overthrow of Saddam Hussein and the fomenting of Isis: in the words of the foreign secretary, Boris Johnson, writing in 2005: “The Iraq war did not introduce the poison into our bloodstream but, yes, the war did help to potentiate that poison.” The hysterical over-reaction to Corbyn’s speech (“monstrous”, according to Johnson) thus looks undignified and politically opportune.

The fundamental problem with Corbyn’s intervention is not what he said, but what he didn’t say. Military interventions in regions where there is religious fundamentalism will carry the risk of terrorist blowback. Does that mean that intervention is never the right course of action? The tests that Corbyn has set for military intervention in recent months – it would need to be backed by a paralysed UN and come with a worked-out plan for lasting peace – effectively rule it out in any conceivable situation. It is disingenuous to pretend that this formula constitutes either an ethical foreign policy or one that might promote global stability.

Both main parties have something to answer for over national security. Theresa May for failing to admit that public spending cuts have affected counter-terrorist operations; Jeremy Corbyn in avoiding the hard questions about what follows – the harsh consequences on the ground – from a non-interventionist foreign policy.

MANCHESTER