Opposing force

An opposing force (abbreviated OPFOR, used in the United States and Australia) or enemy force (used in Canada) 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 main OPFOR role. Other major units include the First United States Army which consists of 16 training brigades that often also serve as OPFOR. Fort Polk's Joint Readiness Training Center is another major training site typically reserved for units that are slated to deploy into conflict areas.

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 emulate real-life enemies, to provide a more realistic experience for their training opponents. (To avoid the diplomatic ramifications of naming a real nation as a likely enemy, training scenarios often use fictionalized versions with different names but similar military characteristics to the expected real-world foes.)

Opposing forces can also coincide with red teaming activities. Once the Analytic Red Team develops adversary tactics, techniques, and procedures (TTPs) it will be the opposing force that makes use of those TTPs in wargames and exercises.

Some dedicated opposing forces may fight using the likely enemy's doctrine, weapons, and equipment. They may wear uniforms which resemble the likely enemy's, or one dissimilar to "friendly forces". Their vehicles may either be those operated by the likely enemy's, or may be modified to look like those. All these measures help to enhance training realism and provide useful lessons on how to fight this particular enemy.

Blank ammunition, smoke grenades, and artillery simulators are often used by both sides in the exercise to provide the fog of war caused by the noise and smoke of battle.

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