The U.S. Air Force, in an effort to save some money, is going to allow its transports (C-5, C-17 and C-130) operating in the United States to use standard airliner fuel, "Jet A", instead of JP-8 military jet fuel. The two fuels are similar, with JP-8 having three additives to make the fuel easier to use in cold weather, and less likely to catch fire when spilled (when fueling or during a crash), less corrosive and so on. These differences make JP-8 a few cents more expensive per gallon. The air force uses about 2.5 billion gallons of fuel a year. In the United States, Jet A is more widely available to military transports (which often operate from commercial air ports) than JP-8, and the military aircraft often use Jet A already with no problems. But the air force is going to do a detailed study of the issue before switching to Jet A for transports in the United States.
JP-8 is a variation on earlier special formulas, like JP-4 (for Arctic use) and JP-5 (for use on aircraft carriers), and was introduced in the 1970s as a standard military fuel for aircraft, and ground vehicles (not to mention stoves in army field kitchens). JP-8 was used as a substitute for several other fuels in the military, in order to simply fuel supply.