cnn businessinsider). The Financial Times writes "oil is the black gold that funds Isis’ black flag — it fuels its war machine, provides electricity and gives the fanatical jihadis critical leverage against their neighbours" (ft.com). The article describes "how oil fuels the jihadi terrorists". Since 2013 the islamic terror organization contros Syria’s oil-rich east.
But there is a positive aspect. Today oil costs about 60% less than at its peak last year. Therefore Isis earns about 60% less from oil, the main income source in the region. As a result the terror organization ha less money to continue the war.
forbes). The US oil boom created an oversupply on the global oil market which let the bubble of the years 2010-14 burst. ISIS is not the only producer who has to deal with a sharply reduced oil income - countries like Venezuela, Russia, Iran, Saudi Arabia- not all friends of the West - have to deal with much less oil income as well. And fracking also reduces the dependence of the US - and the whole world - from the political very unstable and unreliable middle east region.