From World War II, until rather recently, logistics planners could safely assume that, on average, have the tonnage  the supplies they would move would be ammunition, 30 percent would be fuel, and 20 percent would be everything else. In campaigns that involved a lot of moving around, you would use more fuel, and less ammo, and fuel might be as much as 50 percent of the weight of supplies to be moved. But overall, during World War II, you could depend on needing about one gallon of fuel per soldier per day. During the Cold War, the U.S. army got more vehicles, helicopters (big fuel guzzlers) and heavier tanks. The old 50-30-20 ratio held, but the total weight of supplies to be moved nearly doubled from World War II levels. But in Iraq, with its emphasis on infantry combat, and the use of precision smart bombs , instead of many more (and heavier) dumb bombs or artillery, fuel is by far the most common item that has to be shipped. In Iraq, some 70 percent of the tonnage moved is fuel, and it comes to about nine gallons per day per soldier. The demand comes from 27,000 trucks and armored vehicles, hundreds of helicopters and aircraft, thousands of electricity generators (driving thousands of air conditioners and refrigerators). The mobility of American troops is a major factor in their ability to deal with the terrorists and anti-government forces. Fuel, in effect, has become the major weapon used in Iraq. 

Each day, about 2,000 truck tankers leave Kuwait for American bases in Iraq. Over 20,000 troops and civilian contractors do nothing but move this fuel. Thats about ten percent of the troops available (taking into account the civilians involved). While many of the fuel trucks are hit by bullets, RPGs and roadside bombs, casualties to the fuel convoys are lower than for any other type of supplies. This is largely because greater security is provided for fuel and ammunition movements. The fuel convoys are, in effect, rolling traps for any Iraqis foolish enough to try attacking them. As a result, hostile Iraqis seek out less well protected targets, which currently means Iraqi government officials or civilians.