"Islamic State has consolidated its grip on oil supplies in Iraq and now presides over a sophisticated smuggling empire with illegal exports going to Turkey, Jordan and Iran, according to smugglers and Iraqi officials.

Six months after it grabbed vast swaths of territory, the radical militant group is earning millions of dollars a week from its Iraqi oil operations, the US says. Coalition air strikes against tankers and refineries controlled by Isis have merely dented – rather than halted – these exports, it adds."

NY Times "Struggling to Starve ISIS of Oil Revenue, U.S. Seeks Assistance From Turkey"

"The Obama administration is struggling to cut off the millions of dollars in oil revenue that has made the Islamic State in Iraq and Syria one of the wealthiest terror groups in history, but so far has been unable to persuade Turkey, the NATO ally where much of the oil is traded on the black market, to crack down on an extensive sales network.

“They’ve been turning a blind eye to it, because they benefit from the lower price of smuggled black-market oil,” Mr. Phillips said, “and I’m sure there are substantial numbers of Turks that are also profiting from this, maybe even government officials.”

"WASHINGTON—The Obama administration accused Syria’s government of purchasing oil from Islamic State and blacklisted a Syrian-Russian businessman suspected of facilitating those transactions.

The U.S. Treasury Department also penalized Russian and Cypriot businessmen and companies suspected of helping the Syrian central bank evade international sanctions through a web of companies based in Russia, Cyprus and Belize.” - WSJ (Updated Nov. 25, 2015)