Biofuels are already being used for airplanes:
Aviation biofuel - Wikipedia, the free encyclopedia. Since kerosene is similar to jet fuel is similar to diesel, it's relatively easy to run a jet on biofuels
Electric airplanes are also being researched:
Electric aircraft - Wikipedia, the free encyclopedia
Most armored vehicle engines are already Diesel and will run on a variety of source fuels, so running them on biodiesel is not an issue. They are also researching hybrids:
The Army's first hybrid tank
So (sadly), no worries about wars ending.