A German who went to Syria to join Isis has told of how he was asked to return to Europe and carry out attacks there instead.
Speaking to the New York Times, Harry Sarfo, who fled back to Germany from Syria last year after becoming horrified by the group's brutality, explained that Isis attacks in Europe were co-ordinated by its intelligence unit, Emni, run by a Syrian named Abu Muhammad al-Adnani.
Emni, which began as a police force within Isis's territories, has a complex hierarchy and creates small units to carry out attacks, selected by nationality and language.
Sarfo, originally from Bremen, spoke to the New York Times from his maximum security prison cell, where he is serving a three-year sentence and has just completed a year of solitary confinement. He was arrested immediately on his return to Germany in July last year and voluntarily confessed.
Though Sarfo's account cannot be totally verified, prison officials and German intelligence agents are treating him as a credible source, and it is hoped that he could dissuade others from joining Isis.
"They want to have loads of attacks at the same time in England and Germany and France," he said.
Those with European language skills were valuable recruits, he said, as well as Europeans with a criminal past, who may be able to secure fake IDs or assist in smuggling members into the EU.
Sarfo was told that the group was lacking people in Germany and England; attackers who had been sent to carry out attacks had got cold feet.
Chillingly, Sarfo said that when his friend asked about France, the terrorists laughed, saying they had enough people there; this exchange took place several months before the attacks in Paris on November 13th.
Emni is thought to have co-ordinated the attacks in Paris and Brussels, while its soldiers have also been sent to Germany, among other countries.
One worrying detail from the report was a hint from Sarfo that seemingly unconnected attacks in Germany may be more closely linked to Isis than authorities know.
He said that Isis used "clean men" to co-ordinate attacks in Europe to protect Emni members; new converts with no known links to radical groups act as middle men, connecting would-be attackers with Isis's underground operatives in the country.
Germany saw four mass attacks within the span of one week in July: one right-wing, one apparently a crime of passion, and two which had been reportedly inspired by Isis.
Amaq, a news agency linked to Isis, released videos of both an Afghan refugee who attacked train passengers with an axe, and a Syrian who blew himself up in Ansbach last month, showing the attackers pledging allegiance to the group.
Islamism experts suggested that in these and other cases, the group are simply 'exploiting' attacks by lone actors in order to exaggerate their influence; indeed, no evidence emerged of Isis being directly involved in the planning of either attack.
However, Sarfo suggests that the "clean men" are used to pass on instructions to the potential attackers from the operatives on methods as well as how to 'credit' Isis with their attack, and that because the operatives have no direct link with the attackers, they avoid discovery.
The video below shows part of Sarfo's interview with the New York Times.
Sarfo says he believed "hundreds" of foreign fighters had returned to Europe and still had ties to the group.
He added that Europeans wishing to travel to Syria are now encouraged to camouflage their trips as a holiday to Turkey, taking steps such as booking a hotel, but that they are smuggled into Isis territories for 'training days' including weapons practice, taking place over a short time period to avoid suspicion.
Last month, police arrested a man in Germany who had travelled to Syria and who is believed to be closely connected to the planner of the Paris attacks, Abdelhamid Abaaoud.