We report on the development of an agent capability for operational decision-making within a real-time simulation world. A multiple agent system was developed to extend the native behaviors of entities (force units, vehicles, etc.) in tactical simulations. The system endows these entities with intelligent behavior capabilities allowing them to adapt to unexpected scenario situations. The agent system is designed to integrate tightly with the Semi-Automated Forces (SAF) simulators used in live-virtual-constructive simulation environments by DOD and others. Large-scale simulations often entail the necessity of human operators to direct or fill in the ongoing behavior of force units or other entities not being played by trainees or others in the scenario. Force Behavior Agents (FBA) eliminates this staffing requirement, achieves realistic conflict scenarios and, at the same time, simplifies the specification of complex mission scenarios rich in force interaction and variability. In contrast to federate level interaction in High Level Architecture (HLA) communication, FBA is designed to integrate directly with simulators at the fine-grained level of native task frame stacks and simulation state databases. Agent interaction with the simulator's state machines affords the means to adjust unit behavior, including disaggregation, transparently without disrupting normal simulator operations. Selection of alternative behavior tasks during runtime is governed by agents using situation look-ahead trials based strictly on the force unit's qualified sensor capabilities. These look-ahead trials are like sketchy simulations run by the individual agents to find the best alternative courses of action, much as a human commander will survey and compare the tactical options available to his unit. Ontologies define the tactical relations and doctrinal constraints on tasks, and a commercial agent platform provides the decision making environment. An early form of the FBA decision maker and its interface with Joint Semi-Automated Forces (JSAF) simulators was demonstrated to the Joint Forces Command (JFCOM).