The Islamic State group behind the attack on the Crocus music venue near Moscow has also sought recruits in Britain, it can be disclosed.
Through its Amaq news agency, the group claimed responsibility for last Friday’s shooting massacre at the concert hall that killed at least 139 people.
American intelligence sources pointed to ISIS-K, or Islamic State Khorasan Province, as the most likely branch responsible.
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The offshoot group was formed in eastern Afghanistan in January 2015, when tribes formerly associated with the Taliban declared allegiance to Islamic State at a time when the Syria-based group was at the peak of its powers.
Islamic State remains the group of choice for jihadists in the West but Syria is increasingly difficult to access and, instead, a number of recruits in Britain have tried to get to Afghanistan.
Last November, two brothers were jailed after filling out online application forms to join ISIS-K after making homemade videos in which they role-played being suicide bombers.
Haleem Heyder Khan, 21, and his brother, Hamzah Heyder Khan, 18, both from Ward End, Birmingham, had researched how they could travel to Turkey and Iraq before deciding it was too difficult and switching their attention to Pakistan and Afghanistan.
The brothers used Instagram to get in touch with an Islamic State recruiter who sent them forms to fill out in Arabic and a code to access messages on the encrypted WhatsApp messaging service.
Haleem Heyder Khan (left) and his brother Hamzah Heyder Khan were jailed last November for filling out application forms to join ISIS-K. Pic: Counter Terrorism Policing
They purchased and packed clothing and equipment, conducted research into how they could travel to Afghanistan and obtained travel documents for Pakistan.
Detective Chief Superintendent Mark Payne, head of Counter Terrorism Policing West Midlands, warned at the time that the two brothers were intent on becoming martyrs and could have been “redeployed back to the UK”.
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The ISIS-K recruitment form. Pic: Counter Terrorism Policing
Mother charged with trying to radicalise her children
A mother of two from the Midlands has also been arrested and charged with trying to radicalise her children and join the group in an echo of the journeys by families to Syria.
It is said she established online communication with the group to obtain official approval to travel to Afghanistan.
Intelligence agencies concerned group has wider ambitions
MI5 has been concerned by the “ungoverned spaces” in Afghanistan since the collapse of the Western-backed regime in August 2021.
ISIS-K has launched a series of attacks in Afghanistan and has claimed responsibility for attacks across the border in Iran.
Although most of their attacks have been inside Afghanistan, Western intelligence agencies are aware they have wider ambitions.
During the chaotic evacuation of Afghanistan, ISIS-K launched a suicide bomb and gun attack on the queues outside Kabul’s international airport that killed 13 US troops and 170 Afghans.
In January, the Voice of Khorasan, an English-language online magazine linked to ISIS-K, called Britain the “United Kingdom of Kafir”, a term used to refer to non-believers, and drew attention to the country’s role in the Middle East, dating back to the Medieval crusades.
