"Well, we were going to wage jihad to establish an Islamic State in Syria and Iraq, but the U.S. is arming moderates so I guess we’ll stay home.”

 'ISIS in full regalia'

'...  The absence of U.S. troops because of the 2011 withdrawal is an extremely minor part of the story at best. The intense interaction between the Syrian and Iraqi insurgencies is certainly an important accelerant, but again is only part of the story. Nor is the U.S. reluctance to provide more arms to “moderate” Syrian rebels really the key to the growth of ISIS in Syria or in Iraq. It’s a bit hard to believe that the jihadists who have joined up with ISIS would have been deterred by the presence of U.S.-backed forces – “Well, we were going to wage jihad to establish an Islamic State in Syria and Iraq, but the U.S. is arming moderates so I guess we’ll stay home.” In reality, the shift to an externally fueled insurgency and the flow of money and weapons to a variety of armed groups is what created the conditions that allowed ISIS to thrive in the first place...."