Secret efforts to groom and recruit teenagers by a neo-Nazi militant group have been exposed by covert recordings.
They capture senior members of The Base interviewing young applicants and discussing how to radicalise them.
The FBI has described the group as seeking to unite white supremacists around the world and incite a race war.
The recordings were passed to US civil rights organisation, the Southern Poverty Law Center, before some were shared with BBC One's Panorama.
Rinaldo Nazzaro, founder of The Base, is a 47-year-old American. Earlier this year the BBC revealed he was directing the organisation from his upmarket flat in St. Petersburg, Russia.
The interviews, which took place via conference call on an encrypted app, followed a pattern - prospective members were asked by Nazzaro about their personal history, ethnicity, radicalisation journey and experience with weapons, before a panel of senior members posed their own questions.
The would-be recruits were quizzed on what books they had read, including Adolf Hitler's Mein Kampf, and were encouraged to familiarise themselves with the group's white supremacist ideology, which predicts and seeks to accelerate racial warfare, requiring followers to prepare for conflict and social breakdown.
During the calls, Nazzaro can be heard welcoming members of other extremist groups.
The young applicants, who hide behind aliases and display varying degrees of ideological awareness, describe their radicalisation by online videos and propaganda.
When interviewees left the calls, senior members discussed their potential before arranging to vet them in person at a later date.
The recordings make clear that The Base sought to recruit soldiers from western militaries to draw on their training with tactics and firearms.
Nazzaro, who the BBC investigation has been told used to work as an analyst for the FBI and as a contractor for the Pentagon, informed one British teenager that the idea of societal collapse was a "guiding philosophy".
A European teenager was told that such a collapse would be desirable, even at a local level, if it offered a "power vacuum that we can take advantage of".
One boy was told "we have a goal of initially creating two to three man cells in as many areas as possible" and that the "UK is a place that we think there is a lot of potential".
During a post-interview discussion about a 17-year-old from Europe, one older man spoke of "shaping" his belief system, with Nazzaro saying he needed a "little work ideologically" but was "definitely headed in the right direction".
Commenting on one British teenager, Nazzaro suggested he probably needed to "mature ideologically".
Dr Cassie Miller, a senior research analyst at the Southern Poverty Law Center, describes the recordings as a "highly unusual glimpse" into this extreme world, showing there was "no singular pathway to radicalization".
She says those applying to The Base came from a variety of backgrounds.
"I think the fact that a lot of these people are so utterly normal is in itself significant.
"They didn't possess some traits that predispose them to want to become a terrorist or to become attracted to extremist ideology.
"I think it's really best to think of them as a reflection of a society that is so deeply politically polarized".
In the American State of Georgia, three members of The Base are currently facing conspiracy charges for allegedly plotting to murder an anti-fascist couple.
The Base is the latest underground organisation to emerge from an international neo-Nazi network originally generated by a now-defunct web forum called Iron March.
Other organisations include the banned British groups National Action and the Sonnenkrieg Division, as well as the Atomwaffen Division in the USA, which has been dismantled by a nationwide FBI investigation.
The BBC investigation reveals the real identity of a man who is both a senior member of The Base and the creator of a successor online forum linked to several UK terrorism prosecutions involving teenagers.
Matthew Baccari, an unemployed 25-year-old from Southern California, used the alias 'Mathias' to run a notorious website called Fascist Forge, where terrorism and sexual violence were openly encouraged.
He was a vocal presence on The Base interview calls and promoted the group on his website, which he took offline earlier this year following significant attention by law enforcement.
The forum was central to the case of a boy from Durham, who last year - aged 16 - became the youngest person convicted of planning a terror attack in the UK.
Two other young British members of Fascist Forge, one aged 15, are separately making their way through the youth court system charged with a combined 25 terrorism offences.
Baccari refused to leave his bedroom when a BBC team went to his house to ask questions.
Baccari and Nazzaro did not respond to letters setting out the evidence against them.
You can see more on this story on Panorama: Hunting the Neo-Nazis, Monday 22 June at 7.30pm on BBC One, and by listening to File on 4, Tuesday 23 June at 8.00pm on BBC Radio Four
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