The sad truth about the Government’s decision to deploy up to 5,000 troops on British streets is that it is an admission of failure.
It means that the terrorist threat is so serious that the security services believe a terrorist cell “off the radar” is capable of carrying out further attacks.
Operation Temperer, the Government’s secret contingency plan for a post-terror attack like Manchester, was always meant to be a last resort.
And former prime minister David Cameron was always reluctant to authorise the use of the power because of the potential fear and panic he thought it would cause.
He recognised that more soldiers with machine guns can only combat the symptoms of a terror threat. Once an attack has begun and innocent lives taken, it is already too late.
But events in Manchester have shown that the terrorists have already got through.
Britain’s security chiefs have long warned that our cities would eventually succumb to the horrors witnessed in Paris, Brussels, Berlin and Nice. MI5 and the anti-terror police have disrupted 13 plots in the last four years. And in recent months the police have, on average, been making arrests under the Terrorism Act of one a day.
Our security services are being stretched to the very limit.
The terrible questions now facing the authorities are the greatest urgency. Who was helping suicide bomber Salman Abedi and is there a trained bomb-maker still at large?
The price of living in a democracy is that our security services do not possess the powers enjoyed by police states.
But there is still a balance to be struck over the level of personnel employed by a liberal democracy to carry out the surveillance of its citizens.
In the UK the numbers work out like this. There are 6,000 employees at GCHQ, the Government’s surveillance headquarters, and a further 4,000 officers working at MI5, the domestic security service.
But there are up to 3,000 terror suspects in the UK who the security services have identified as posing a potential risk. To continuously monitor one individual requires 20 officers. This means the security services would require 60,000 officers to track every suspect of interest all the time. These kinds of numbers of secret agents spying on the British public are politically unacceptable.
And even the security services aren’t requesting such resources, partly because they understand that further deployment of thousands more officers in the “war on the terror” does not guarantee that another committed terrorist “off the radar” will not get through.
The question is whether Manchester marks a turning point in our democracy and whether the public will demand more security service officers and more counter-terrorism power.
But the horror of Monday night’s terror attack on Manchester exposed Britons to what the citizens of Paris, Berlin and Nice already know: that in the current, febrile climate of violent Islamist terrorism there is little defence against those who are committed to killing.
Robert Verkaik is the author of ‘Jihadi John, the Making of a Terrorist’
He tweets at: @robertverkaik1