It looks like the United States' policy to go to war in oil-rich nations to satisfy its oil-craving is a self-feeding loop (via Emptywheel).
A Deloitte study of the U.S. military's fossil fuel consumption shows that the U.S. needs more oil to fight wars than it used to. Since the Vietnam war, there has been a 175% increase in the gallons of fuel consumed per soldier, per day.
The cost of transporting fuel to far flung places, the greater mechanization of war technology, and the ragged terrain and irregular nature of the warfare (read: Afghanistan) are responsible for the increase, according to the study.
The military is trying to go green by improving fuel efficiency and trying out alternative fuels. Some other interesting observations:
This increase has occurred despite the significant increase in fuel efficiency in internal combustion and jet engines used with armored vehicles, tanks, ships and jet aircraft, and the use of nuclear-powered aircraft carriers and submarines. However, these significant improvements in efficiency are vastly overshadowed by the higher number of vehicles and increasing rate of use.
Furthermore, the increasing number of convoys required to transport an ever increasing requirement for fossil fuels is itself a root cause of casualties, both wounded and killed in action. The use of IEDs and roadside bombs has been an especially effective means to disable friendly fighting forces by disrupting their supply of energy. The Deloitte study found that absent game-changing shifts, the current Afghan conflict may result in a 124% (17.5% annually) increase in U.S. casualties through 2014, should the war be prosecuted with a similar profile to Operation Iraqi Freedom (OIF).