Gameplay focuses heavily on creating a balance between offense, defense, and economy. This force is under the authority of both the Defense and the Interior Ministry. The administration pursued a national missile defense. There were simulations of air combat, ballistic missile defense and amphibious landings. Farmers have found the use of chilies effective in crop defense against elephants. Serling offers many valid arguments on behalf of both the defense and the prosecution. I believe in a strong national defense. That approach led to maintenance of a Territorial Defense system. The effectiveness and safety of guns used for personal defense is debated. Phagocytosis is one of the main mechanisms of the innate immune defense. Aster 30 is capable of ballistic missile defense. Stevenson was known for his defense and athleticism. Houston could not spare the number of men necessary to mount a successful defense. Population fluctuates depending on operations being conducted by Missile Defense Agency activities. These attacker advantages cause challenges for defense mechanisms.