The naval simulation system (NSS) is an object-oriented, Monte Carlo, multiresolution constructive simulation under development for naval operations—OPNAV N812 and OPNAV N62. It has a planned (future) virtual simulation mode of operation. NSS is being developed for use in simulating naval operations in support of analyses of tactics, decision support applications, and training (Stevens and Parish, 1996). It provides explicit treatment of command structures from the national to the operating unit level, operational plans and tactics, sensors, weapons, and countermeasures. The simulation applies situation awareness based on a commander's perception of the status of friendly, neutral, and hostile forces. Tactics are represented by means of what is termed a decision table, although it might be more properly termed a prioritized production rule system. The simulation normally operates faster than real time. The basic unit is the ''entity," typically a ship or aircraft. Explicit representations are included for the "hardware" component, consisting of the environment, sensors, weapons, and communications channels, and the "software" component, consisting of the command structure, the data fusion process, the tactics, and the operational plans. This latter set of components is the key determinant of unit behavior. The data fusion process serves to generate the tactical picture or the assessed situation. This, in combination with the tactics, generates the unit behavior.

The Marine air-ground task force tactical warfare system (MTWS) is a commander and staff air and ground training simulation that simulates the ground combat of a task force and its air and indirect fire support elements. It is used as a staff trainer, but not validated for analysis. MTWS unit behavior is not sophisticated, and the simulation does not model individual behavior. Doctrine is parametric, and communications is not represented. The simulation is controlled by human controllers whose skills are critical to the realism of the play.

The advanced air-to-air system performance evaluation model (AASPEM) 4.1 is a comprehensive tool for performing air combat analysis in a realistic few-on-few engagement environment of up to 75 aircraft and missile combinations for six different aircraft and six different missiles at a time. AASPEM can be used to explore tactics, maneuver versus detection, launch ranges, flight testing, and mission planning. It has been used for studies of the effectiveness of new