Unprecedented threat level 'new reality' for counter-terror agents

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Britain's counter-terror agencies are adapting to a "new reality" with the threat of attacks now at an unprecedented level.

As a flurry of murderous strikes by Islamist terrorists hit other European countries, senior figures repeatedly warned that the UK would also be targeted.

But the pace and scale of the danger appears to have ratcheted up even more in recent weeks.

It was revealed last month that police and security services have foiled 18 plots since 2013 - including five in just nine weeks weeks after Khalid Masood's deadly rampage at Westminster in March.

Authorities are likely to face questions again after the London Bridge attack about whether the perpetrators were on their radar and whether any opportunities to intervene were missed.

The sheer volume of activity being undertaken by MI5 and its partners to contain the threat was laid bare in the wake of the Manchester bombing last month.

Figures show the agency is managing around 500 active investigations involving around 3,000 individuals at any one time.

But in addition there are also a larger pool of as many as 20,000 people who have been considered at some point in the past but are not included in the live probes.

The spotlight has fallen on how closely those in the second, larger group are monitored after it emerged that the Manchester attacker Salman Abedi was a former "subject of interest".

On Monday, Scotland Yard chief Cressida Dick, who worked in counter-terror earlier in her career, described the recent wave of attacks as "unprecedented in my working life".

She said: "We in this country have faced a terrorist threat throughout my life - it changed and morphed and we will change and adapt to what appears to be a new reality for us."

A major challenge for counter-terror units is the breadth of the potential tactics that terrorists may use.

Chiefs remain concerned about the potential for complex, mass-casualty plots such as the July 7 bombings in 2005.

But the Westminster and London Bridge outrages have underlined the carnage that can be wrought by driving vehicles into pedestrians and attacking with knives.

These "low-tech" methods are associated in particular with Islamic State, and have proved difficult to anticipate and prevent.

Security services are also having to contend with the increasingly rapid pace of radicalisation that can mean someone seen as posing little or no risk shifts quickly to the point of violence.

The latest atrocity has also sparked fears that Britain is in the grip of a flurry of copycat incidents, with Ms Dick acknowledging that it was "certainly a possibility" that attacks were triggering the ones to follow.

All of the recent attacks had a "primarily domestic centre of gravity", the Metropolitan Police Commissioner said.

"We will always be looking to see if anything has been directed from overseas, but I would say the majority of the threat that we are facing at the moment does not appear to be directed from overseas," she added.