United Arab Emirates warplanes operating out of Jordan have attacked targets inside ISIS-held territory in Syria. Though details are still scant, they reportedly targeted oil refineries.
The US has similarly been keen to attack oil infrastructure in ISIS territory, which in Syria centers around some of the most oil rich parts of the nation. ISIS taxes the oil, like most states do, and it is a significant source of funding for them.
At the same time, ISIS largely doesn’t operate the oil infrastructure itself, but leaves that to local tribal factions, and simply taxes them. The attacks thus are on civilian infrastructure.
In the long run, such attacks are badly impoverishing the civilian population in eastern Syria, with an eye on so badly crippling the economy of the region that it will also hurt ISIS. This tactic has worked badly in the past, and has often forced civilian populations to be deeper dependent on their rulers as the one force left resisting the foreign attacks.