An opposing force is a military unit tasked with representing an enemy, usually for training purposes in war game scenarios. The related concept of aggressor squadron is used by some air forces. The United States maintains the Fort Irwin National Training Center with the 11th Armored Cavalry Regiment serving in the OPFOR role. Fort Polk's Joint Readiness Training Center (JRTC)is another major training site typically reserved for light infantry units, and the OPFOR are the 1st of the 509th Airborne Infantry Battalion. The Army's Joint Maneuver Readiness Center has the 1st of the 4th Infantry Battalion as their OPFOR. Other major units include the First United States Army which consists of 16 training brigades that often also serve as OPFOR. At a basic level, a unit might serve as an opposing force for a single scenario, differing from its 'opponents' only in the objectives it is given. However, major armies commonly maintain specialized groups trained to accurately replicate real-life enemies, to provide a more realistic experience for their training opponents.
