Newly-declassified US Defense Intelligence Agency (DIA) documents from 2012:
In Syria:
THE SALAFIST [sic], THE MUSLIM BROTHERHOOD, AND AQI ARE THE MAJOR FORCES DRIVING THE INSURGENCY IN SYRIA.
AQI [Al Qaeda in Iraq, which became ISIS: “ISIS, once called AQI”] SUPPORTED THE SYRIAN OPPOSITION FROM THE BEGINNING, BOTH IDEOLOGICALLY AND THROUGH THE MEDIA…
…OPPOSITION FORCES ARE TRYING TO CONTROL THE EASTERN AREAS (HASAKA AND DER ZOR), ADJACENT TO THE WESTERN IRAQI PROVINCES (MOSUL AND ANBAR), IN ADDITION TO NEIGHBORING TURKISH BORDERS. WESTERN COUNTRIES, THE GULF STATES AND TURKEY ARE SUPPORTING THESE EFFORTS.
IF THE SITUATION UNRAVELS THERE IS THE POSSIBILITY OF ESTABLISHING A DECLARED OR UNDECLARED SALAFIST PRINCIPALITY IN EASTERN SYRIA (HASAKA AND DER ZOR), AND THIS IS EXACTLY WHAT THE SUPPORTING POWERS TO THE OPPOSITION WANT, IN ORDER TO ISOLATE THE SYRIAN REGIME…
Now for some definitions: