The main military force mentioned is the Space Corps, composed of marines and fleets, who fight against alien races that threaten the colonies. (When originally introduced in "The Corps" spinoff, they were Judges from the Academy of Law but in later stories these are recruited citizens.) Another force are the Genetic Infantry: genetically engineered men, bred in a lab to be dedicated soldiers. (The story "Warzone" had an ex-Genetic Infantry soldier who was a primitive version of the Genetic Infantry from "Rogue Trooper".) The Citi-Defs (Citizen Defence) are a reserve force composed of citizens. Each city block contains a Citi-Def force in case of crises, though usually they turn up in "Dredd" as rogue factions waging block wars.