In September 2014 the United States and Coalition partners conducted aerial attacks against several Islamic State-operated modular oil refineries in Syria. The Pentagon’s rationale is that the refineries provided fuel for Islamic State operations, money to finance continued attacks and constituted an economic asset to support future operations. Attacking the oil production facilities to stop the sale of smuggled oil, the proceeds of which “fuel” Islamic State activities is potentially controversial. Additional Protocol I limits attacks to those objects that “make an effective contribution to military action.” The U.S. position is that “war-sustaining objects” may also be lawfully targeted, thus including a much broader justification for the use of force. The article examines the issue of where to draw the line between objects being struck and the military activity of the Islamic State, as well as a number of other targeting issues.