A senior official in the US Department of the Treasury says that most of the oil in ISIS's hands was sold to Syrian dictator Bashar al-Assad's government, though a large amount was also sold to Turkey.
"ISIL [ISIS] is selling a great deal of oil to the Assad regime," said the Department's acting under secretary for Terrorism and Financial Intelligence. He added that "The two are trying to slaughter each other and they are still engaged in millions and millions of dollars of trade"