The hidden hand behind the Islamic State militants? Saddam Hussein’s.

Some of them had fought against al-Qaeda after changing sides and aligning with the American-backed Awakening movement during the surge of troops in 2007. When U.S. troops withdrew and the Iraqi government abandoned the Awakening fighters, the Islamic State was the only surviving option for those who felt betrayed and wanted to change sides again, said Brian Fishman, who researched the group in Iraq for West Point’s Combating Terrorism Center and is now a fellow with the New America Foundation.