Amos Hochstein, the State Department’s special envoy and coordinator for International Energy Affairs, said Dec. 8 that the US-led effort to reduce Islamic State (IS) oil revenues has been “remarkably successful in a relatively short period of time,” but independent experts questioned whether the gains extend to local markets and long-standing smuggling corridors.

Hochstein provided no firm estimates about the amount of oil and refined products the jihadist group is selling but asserted, in comments before the American Security Project, that “the Wild West days are over” when it comes to such sales.

Six weeks ago, Treasury Undersecretary David Cohen told another Washington audience that the multinational effort to defund IS was "in the early stages" and that the group was earning $1 million to $2 million a day just from smuggling oil.

Hochstein said that coalition bombing had destroyed much of the militant organization’s refining capacity and that the Turks and the Kurdistan Regional Government (KRG) in northern Iraq had responded to US appeals and begun to crack down on smugglers moving oil from IS-controlled areas in Iraq and Syria.