'Explosion' in child internet sex abuse
18 June 2014 Last updated at 20:13 BST
The online trade in images that show child sex abuse is now "an epidemic", the head of the global initiative to combat the problem has warned.
Ian Quinn, who chairs the international Virtual Global Taskforce, told the BBC that there has been an "explosion" in cases handled by US authorities.
The BBC's Angus Crawford joined a recent operation in Los Angeles.