"They (ISIS) operates on a different network from the internet that we use. It seems, locked in dark ISIS web can be done," said Jared Cohen, Director of Google Ideas.
Dark Web is accessing content on the internet that requires software, configuration, or special permission. Contents in it can not be indexed by search engines, such as Google.
According to Cohen, the extremists should know that doing propaganda on the Internet are also at risk, can not be done freely.
By making content-related content ISIS to dark web, propaganda spread can not be spread freely.
In fact, Cohen had a desire for social media account faster ISIS as far as possible removed before the operation so that complicates their communication with recruiters.