Modern air defense at sea doctrines need to consider the emerging technology of software-defined radar. In this manner the surveillance and tracking abilities of imaging radar are implemented in software. Concurrently there exists the need to forge the other side of the same coin. The Software-defined Radar Countermeasure System (S-dRCS) might be a solution for confusing adversary radar operators. In this spirit the current contribution is the proof of concept for a S-dRCS special case called the Simulator-defined Radar Countermeasure System (Sim-dRCS). The simulator approach for imaging radar countermeasures is preferred because it provides a bespoke generation of the required signals valid for a diverse set of adversary observers, which are considered to be Inverse Synthetic Aperture Radar systems. The simulator receives input from the sensors of the Sim-dRCS and then crafts false targets matched to the heading and velocity vectors of the threat. In this case the countermeasure output is a battleship-class false naval target. The achievement of verisimility enhancement is the main requirement in order to support this deceptive stratagem.