The map below gives an indication of how successful they've been, and it is quite troubling given that sectarian killings are rising along with the group's influence.

The scariest part is not even highlighted: Next door in Syria, the Islamic State in Iraq and al-Sham (ISIS) administrates the largest rebel-held city, Raqqa, and fights to control the shared borders of both Iraq and Turkey.

"Establishing a geographical area comprising natural resources such as oil and gas and totally dominated by Sunnis is a priority for the [ISIS] in this stage," a retired senior military officer who was responsible for making plans to combat al Qaeda told Reuters.