Salman Abedi was British by birth, Libyan by background, a radical Islamist by identity, loyal to a “caliphate” based in Raqqa, Syria. These facts should be the starting point of our response to the atrocity he perpetrated: the threat is global, yet our state is national, and our communities local. Our state and our communities were not strong enough to stop him. The time to discuss why is not after the election, but now.

The “blowback theory”, which blames Islamist terrorism directly on western expeditionary warfare, is both facile and irrelevant in this case. By bombing Libya we did not enrage or radicalise young Muslims such as Abedi: we simply gave them space to operate in. And then, whatever the intelligence services were doing, the politicians took their eye off the ball.

David Cameron was right to take military action to stop Gaddafi massacring his own people during the Libyan uprising of 2011: the action was sanctioned by the UN, proportionate, had no chance of escalating into an occupation. And Cameron and Nicolas Sarkozy had a stabilisation plan. The problem is they had no plan for what to do if their plan went wrong. Nor, it appears, did Cameron’s ministers concern themselves about how a failed state in Libya might affect the growth of global jihadism, and the domestic terror threat in the UK.

In January 2016, in evidence to the foreign affairs committee, Liam Fox, defence secretary in 2011, was asked if the government had made an assessment of the threat of Islamic extremism among anti-Gaddafi rebels. Fox replied: “I do not recall reading anything of that nature. That is not to say it would not have been done, but I don’t recall reading such material … I do not recall reading any reports that set out the background of any Islamist activity to specific rebel groups.”

It is an astonishing failure. Because, as the committee report makes clear, from February 2011 Islamist rebels detached themselves from the main rebel militia, refused to take orders from it and killed its main commander. By October, the situation was out of control. Theresa May, as home secretary, sat through 55 national security council meetings on Libya between March and November 2011. The national security adviser’s “lessons learned” report makes no mention of any Home Office contribution to that body’s decisions, nor any mention of the implications for domestic terror.

It is now reported that MI5 was facilitating the travel of non-jihadi British Libyans to fight in Tripoli. The minister responsible for that decision would have been May. Did she ask about the impact of the Libyan fighting on the terror threat here? That would be something the newspapers, if they did their job, would be shouting at her today, instead of hurling insults at Jeremy Corbyn.

In July 2011, as the fighting raged, May did warn that al-Qaida was seizing arms in Libya. However, she concluded, because of the Arab spring, “al-Qaida is failing”. Unfortunately it was the Arab spring that failed, and the rise of Islamic State was one of the results.

In January this year May pulled the plug on any future strategy of regime change and foreign intervention, implicitly criticising Cameron’s Libya strategy. Speaking in Philadelphia, she decried “the failed policies of the past”.

But it is the job of a government to do more than decry things. It has to deal with the mess created. And to do that, it has to ask a question May never bothered with: are cuts to the police and defence budgets sustainable in the context of the increased terror threat?

May’s response, to the rooms full of police federation reps who did raise it, year after year, was to reject the premise of the question. Now, with the terror threat at critical, she has had to deploy troops to guard key installations.

No matter by how much the budgets of GCHQ and MI5 have been boosted, in an attack such as this – and the threat is ongoing – it is the resilience of police, fire and A&E departments that is tested. The troop deployment is a tacit admission that this resilience is under strain.

Reversing police budget cuts now, as Labour has promised, should be mandatory. If anything, the recent spate of attacks – both failed and successful – shows the need for a more strategic rethink.

Britain needs the equivalent of the French GIGN, the full-time paramilitary force deployed to deal with the Bataclan attack. Such a force would need a new legal framework and heavy investment in extra resources – not, as now, resources borrowed from frontline police and special forces.

The Manchester massacre should be a wake-up call

But above all Britain needs to be in active collaboration with security services across Europe. Reports suggest the explosives used by Abedi, the bomb design and the networks utilised were those of radicalised north Africans living in European cities.

As they constructed their Brexit strategy, senior civil servants briefed journalists that May was prepared to threaten the EU with withdrawal of security and intelligence co-operation. May stupidly included the threat in her article 50 letter, later claiming it was not a threat at all. How hollow and foolish that all sounds now.

The Manchester massacre should be a wake-up call. This is a government of amateurs; Fox didn’t bother to ask about the terror implications when we bombed Libya; May lost 19,000 police in the face of reasoned warnings. Unfortunately the enemy we are fighting are professionals.

Jeremy Corbyn has, ignored by the commentators, repeatedly used prime minister’s questions to warn about the impact of police cuts on our security. He has – at every point – done what May and Fox did not: asked the right questions.

Laugh, if you want, at Diane Abbott’s failure to answer the question: how much would 10,000 extra police cost? But it was the wrong question. With the Isis caliphate about to collapse in Raqqa and Mosul, spreading its survivors into the refugee trails of Europe, I don’t care how much 10,000 new officers cost. The right question is: how soon can they start?