Social media networks are being used by people with extreme views to galvanise into plotting terrorist attacks, Britain's internal security agency MI5's behavioural science unit has warned.
The intelligence unit, which is in the process of expanding, includes psychologists, anthropologists and psychiatrists who analyse the online behaviour of extremists to identify the mental health conditions that could lead to an attack.
It has found that extremists find a form of legitimacy by social media networks such as Twitter and YouTube, often hiding behind anonymity.
"Social media provides a forum in which people can explore their dark thoughts in the company of like-minded people," Alex, an MI5 officer, was quoted as saying by 'The Sunday Times'.
"This creates an echo chamber, providing legitimacy to people with extreme views and galvanising them to act," added the member of the MI5 behavioural unit, whose full name has been withheld for security reasons.
The unit has reportedly helped to foil 14 terror plots in the UK since the Westminster Bridge attack in London in March 2017, when five people were killed and 49 injured. It warns MI5 officers and agents against thinking that terrorists are "mad" even if their behaviour seems inexplicable.
More From This Section
"Not all terrorists have mental health problems and not all people with mental health problems are likely to become terrorists," one of its documents says. But, it adds, some mental health problems can lead to an openness to terrorism: the need for purpose, self-efficacy or to feel valued; a need for belonging; perception of injustice or a sensitivity to perceiving injustice.
In April 2017, the unit's officers helped to stop Khalid Ali, who had planned a knife attack near Downing Street, and then went on to quash the UK's first all-female terrorist cell. Safaa Boular and her sister Rizlaine were later given life sentences and their mother, Mina Dich, was also imprisoned.
While the majority of MI5's 600 investigations concern Islamist radicals, the agency has expanded its surveillance since taking responsibility for tackling far-right extremism in October.
The intelligence service is believed to be reinvestigating some of its 20,000 former "subjects of interest" to assess whether they are likely to engage in terrorism.