The incel movement is a small but growing concern to police in the UK.
The “involuntarily celibate” online subculture involves men who express hostility and extreme resentment towards those who are sexually active, particularly women.
It is increasingly part of a “squashed down” set of extreme ideologies that also include Satanism and the occult, as well as an interest in high school shootings.
The movement first became violent when Elliot Rodger stabbed dead three and shot another three fellow students at the University of California before killing himself in May 2014.
Rodger left behind a 137-page “manifesto” and a YouTube video revealing that he carried out the attack because he could not secure a relationship with a woman, which in turn led to his hatred for those who were in relationships.
The misogynistic incel movement has now been associated with at least six mass shootings and the murder of 46 people in the US.
Plymouth mass shooter Jake Davison repeatedly spoke about incels in a series of videos shared online.
Although saying he did not “clarify” himself as an “incel”, Davison talked about “people similar to me have had nothing but themselves”.
The 22-year-old shot and killed five people, including a three-year-old girl, before turning the gun on himself during a six-minute shooting spree in the Keyham area of the city on Thursday evening.
Recent police investigations in the UK prevented two men linked to the incel movement from taking violent action.
Anwar Said Driouich, 22 from Middlesbrough, was jailed in March last year after collecting bomb-making chemicals, explosives manuals, knives and balaclavas.
He had used the password “killer” on his mobile phone and told a friend he wanted to launch a “massacre”.
Police were called in by a chemical supplier after Driouich bought 10kg of ammonium nitrate online, paying £199.80 on 14 August last year.
Inquiries into his purchases showed that it was his second purchase of the chemical and he had also bought weapons such as a knuckleduster, handcuffs, full-face balaclavas, and two wireless firework firing systems with an electric igniter fuse.
In one Facebook message from 31 March, Driouich and a friend discussed their perceived hardships in life and Driouich said he wanted to end it all.
Driouich stated: “It’s f**king humiliating I have no hope with girls man I might aswell be a ghost to them its pathetic.
“It feels like there is hardly any point trying now…I want to massacre this place man.”
His internet browsing history showed that Driouich had accessed an incel website on the day before his arrest, and viewed a post with the title, “Could be another ER coming up soon” – referring to Rodger.
Earlier this year, a Cambridge University maths graduate was also jailed after he bought a copy of a bomb-making manual on Amazon.
Oliver Bel, 24, from Wilmslow, Cheshire, had said he wanted to “go ER”.
Jonathan Hall QC, the terrorism watchdog, last month referred to the threat from terrorism becoming “more blurred”, where it is “hard to distinguish between what is conventionally understood as terrorism and what is not”.
He said there were “considerable difficulties” in identifying whether desires to kill expressed online, particularly when expressed by the young, will translate into acts of terrorism in real life.
“If there is an ideological component, and I think there may well be one, it is a nihilism which seeks the end of days,” he said.
“It has something akin to the revolution of the unhappy or the ‘beta uprising’ carried out by incels or involuntary celibates.”