"The Story of AFDS is set in a fictional-time (20X1-20X7) when scientific technology has reached an all new level and the ability to cure almost all Human diseases has become a reality. However, as a result, the Earth has become overpopulated and basic necessities are becoming scarce. In the midst of the growing epidemic, those nations that are highly industrialized but not producing enough food for themselves banded to form the "United Forces" and use their military advantage to seize agricultural lands whereas those nations that are under the threat of United Forces invasion have pooled their resources to form the "Allied Forces."
Source: Wikipedia, "http://en.wikipedia.org/wiki/AirForce_Delta_Storm," available under the CC-BY-SA License.