Understanding scale of terrorist threat is key to protecting public – Angus Robertson

The horrific attacks on shoppers in Streatham, South London, show the difficulty of protecting the public from violent extremists, writes Angus Roberston.

Police forensics officers at the scene of Sunday's terrorist attack (Picture: Victoria Jones/PA)

Liberal democratic societies face a major challenge of how to deal with violent extremists. The job of the police and security services in keeping the law-abiding public safe is extraordinarily difficult and arguably getting more difficult every day.

The advent of social media has exponentially raised the challenge, as potential terrorists can become radicalised and inspired to pursue violence from websites accessed in the privacy of their own bedroom.

Immediately after any terrorism incident our thoughts are with the victims, their families and friends. No one in South London or anywhere else should have to worry for their lives when popping out to the shops.

Massive appreciation goes to the first responders who sped towards danger to try and save lives. The horrific weekend scenes in Streatham after a young man attacked Sunday shoppers have become all too familiar. It is only a short matter of weeks ago that a knife-wielding attacker was tackled on London bridge, after killing two people.

In both cases, the terrorists were known to the authorities, had served jail time and had been released from custody. Despite listing ‘dying a martyr’ as a life goal, the Streatham attacker was free to walk the streets. Judging by the speed of the police response, it seems he was under close surveillance, but not close enough to stop the start of his rampage.

At any one time in the UK, there are 3000 people of major terrorist concern to the police and security services. Understanding the scale of the challenge as well as the legal limits will be key to protecting society.