On March 10, 2015, the hacker collective Anonymous announced that it had taken down the website and Facebook page of the new pro-ISIS social network Khilafa Book as part of #OpISIS, which involves targeting social media accounts and websites that promote ISIS ideology.
The previous day, on March 9, 2015, the operators of Khilafa-Book had claimed that the website was shut down "in order to protect the info and details of it's [sic.] members and their safety."
Source: Techworm.com, March 11, 2015.