Reuters reports: Islamic State is still extracting and selling oil in Syria and has adapted its trading techniques despite a month of strikes by U.S.-led forces aimed at cutting off this major source of income for the group, residents, oil executives and traders say.

While the raids by U.S. and Arab forces have targeted some small makeshift oil refineries run by locals in eastern areas controlled by Islamic State, they have avoided the wells the group controls.

This has limited the effectiveness of the campaign and means the militants are able to profit from crude sales of up to $2 million a day, according to oil workers in Syria, former oil executives and energy experts.