The extent to which Islamic State militants in Iraq have used social media to wage psychological warfare and rally support for their cause has been criticised in recent weeks.
 
Since IS started forcing Yazidi and Christian families from their homes, the group has launched numerous Twitter accounts, only to see them shut down as quickly as they are set up. 
 
And international pressure is strong for broadcasters and social media platforms not to show the graphic images of James Foley's death and not to give IS the oxygen of publicity that it wants.
 
Our reporter Charlotte Cross is across this story.