MI5 failings in the Manchester Arena bombing suggest it may be time to expand our secret defences

The final report into the Manchester Arena bombing contains a particularly disturbing revelation. It was a horrific attack, targeting as it did young people and their families attending an Ariana Grande concert on 22 May 2017. A total of 22 people were killed and 1,017 were injured, many seriously, by Salman Abedi’s shrapnel-laden device. It seems this horror could have been averted.

We now know Abedi was on the radar of the security services, and that a meeting had been arranged to discuss his case, scheduled for 31 May – nine days after the attack. He was not under active investigation when he detonated his bomb, even though MI5 had key information about his activities. According to the report of the inquiry led by Sir John Saunders, the Security Service missed a “significant” chance to stop the attack.

The precise nature of the intelligence received before the attack has been withheld for reasons of national security, but there seems no cause to doubt Sir John’s finding that it was linked to Abedi’s plot. His judgement was that “an ordinary member of the public would be deeply concerned to find out that, some time before the attack, the Security Service had information that transpired to be relevant to Abedi’s plan and yet took no action in response.”

That is correct, and there is also no reason to dispute that “there was a realistic possibility that actionable intelligence could have been obtained which might have led to actions preventing the attack”.

So there it is: a failure. Not a certain failure, but a “realistic possibility” that if an officer had acted more swiftly, then Abedi might have been tracked and stopped. It is grievous enough, and for the former judge to be quite so explicit about this detail suggests that things might well have been different.

Yet the security services are entitled to put this error into an appropriate context, and that context was an unprecedented level of terrorist threat following the emergence of Isis. While the government was trying to prevent foreign fighters from flowing to the group’s territory abroad – and coming back – supporters left at home were hatching their own domestic plans.

The threat has now morphed, and comes from an ever-growing array of sources, including extreme right-wing terrorism and people driven by conspiracy theories. Hostile state threats are taking up ever more of the service’s limited resources. Russia, Iran and China are currently generating the highest level of concern, with nefarious activity ranging from the targeting of dissidents in the UK to espionage and cyberattacks.

On the domestic front, the main terror threat now stems from ‘lone actors’, who are harder to spot and stop than their predecessors in real-world networks that could be infiltrated and watched. Isis and al-Qaeda continue to inspire, and the prevalence of motivational propaganda and bomb-making terrorist “cookbooks” online means that a serious incident is more likely.

There are 3,000 “subjects of interest” currently under some level of live investigation by MI5, and it is simply not possible to place surveillance on all of them. In a free society, it is also impossible to prevent terrorism, and the 30-year duration of the Troubles in Northern Ireland highlights the fact that even in a heavily militarised environment, sometimes the bombers will get through.

Since the upsurge in Islamist terror in the West about two decades ago, strongly marked by 9/11, and the recent wave of extreme right-wing terrorism, the security services and the police have foiled dozens of terror plots. Unlike in Northern Ireland and other societies blighted by the curse, terrorism has not become routine or endemic in the UK. Such success is down to the largely unseen efforts of dedicated public servants, who are as hard-pressed and prone to error as anyone – and for whom the stakes could barely be higher.

Lessons will be learnt. Sir John will make some timely recommendations. The tech giants can always do more to take down the propaganda (such as the material that attracted Shamima Begum to Isis) and the terror manuals. Retailers can surely do more to report suspicious purchases of materials for bomb-making, and should not be shy about doing so.

Extreme right-wing terrorism needs to be taken seriously, and those fomenting it challenged, at both a security and a political level. Recent violent protests against asylum seekers staying in hotels are an example of how easy far-right groups find it to exploit people’s anxieties and grievances. Social media has allowed antisemites, Holocaust deniers and out-and-out Nazis to form informal networks. Some openly espouse violence. Initiatives such as Prevent, rightly praised by Sir John, can only do so much against such a backdrop.

Time and again, as with other vital public services, resources become an issue. In the Abedi case, MI5’s northwest investigative branch was “struggling to cope” with the volume of investigations, to the extent that one officer had expressed concern that “something inevitably would happen at some point”.

Balanced as always, Sir John concluded that the pressure on resources did not cause any of the missed opportunities in Abedi’s case, but contributed towards the wider underestimation of the threat from Libya. Such pressures are almost certainly hindering the war on terror now. It may be time to try to expand our “secret” defences.