The standardization of training and simulation protocols through the SIMNET/DIS concept creates a unique opportunity to maximize the productivity of existing fielded systems. The adaptation of trainer protocols to SIMNET/DIS protocols will allow trainers to be integrated with distributed simulation networks, thus expanding SIMNET/DIS to better simulate and model the complete air-land battlefield. The focus of our work has been in the design and development of a general form protocol converter to adapt air defense trainers/simulators to a distributed simulation network. The air defense protocol converter incorporates generic air defense processing models, a menu driven user interface for customizing the protocol converter, and an object oriented design with clearly defined interfaces between models. The protocol converter houses all of the SIMNET processing needed for air defense systems to participate in a SIMNET exercise. In addition, we have defined a minimal set of messages between the air defense trainer and the protocol converter, which contains typical information available to the trainer. The protocol converter uses information from the generic interface message set and the user interface files to provide an air defense application with an intelligent interface to SIMNET, which can be easily expanded to address DIS.