- Fareed Zakaria: ISIS has thrived because of a local Sunni cause in Syria and Iraq
- Leaders of ISIS have recognized they are a messaging machine, he says
This is an adapted version of the conclusion to "Blindsided: How ISIS Shook the World," a "GPS" special airing Sunday at 7 p.m. ET on CNN.
(CNN)It's easy to be anxious about the threat posed by the Islamic State of Iraq and Syria. After all, this is a brutal organization that not only kills but seems to revel in doing so in ways designed to shock the world -- from the beheadings of journalists to burning a Jordanian pilot alive. Such moves are part of this murky group's propaganda and its deliberate efforts to manipulate information.