A massive haul of terrorist propaganda has been discovered online in a two-day operation.
Investigators found 1,628 pieces of terrorist and extremist material designed to radicalise and recruit people for mainly Islamic State or al Qaeda.
The Europol-coordinated inquiry also found terror groups have been using the darknet as a directory for radicalised material they push out on the open internet.
These darknet services – which are not accessible without specific software – were being used like libraries pointing to terrorist content on the public internet.
It follows an investigation earlier this year which discovered manuals on making terror devices were openly available on Facebook and YouTube.
In the latest operation, investigators passed the content, all found on the open internet, on to a Europol unit which then contacts those hosting it and suggests they voluntarily take it down.
While this is usually quite successful, a Sky source suggested that material hosted in distant locations such as Indonesian and Malaysia was often more difficult to get removed.
In the past, when those hosting this content were not responsive, contact to those providers’ other clients was made to inform them that they were sharing a host with the proscribed group.
Sky’s source suggested this was an effective tactic, but also quite work-intensive and one which seems not to be common practice at the moment.
Removing terrorist content, while a key part of counter-terror activity which seeks to prevent radicalisation, also provides a challenge for those gathering intelligence on those accessing and disseminating this material.
Additionally, many forum administrators are by now used to operating in a hostile environment, and usually have plans in place to quickly relocate to a new hosting provider.
(c) Sky News 2017: Online terror propaganda haul bagged by Europol