The observable infrared signature of naval platforms is crucial in determining survivability and is therefore an important issue in warfare. Increased detectability in the EM spectrum leads to higher susceptibility against threats like sea skimming anti-ship missiles. The infrared platform signature is not a fixed quantity but a highly dynamic property that varies significantly depending on the prevailing conditions. To reduce susceptibility, active reduction measures can be deployed that reduce surface and exhaust gas temperatures and therefore actively obfuscate the signature. Since infrared decoy countermeasures compete with the platform signature, these reduction measures can positively affect countermeasure effectiveness, enabling enhanced interruption of the kill chain. To enable accurate signature reduction, improved awareness of the platform’s current signature is required. A sensor driven system on board of a platform, combined with specialized modelling capacity is capable of monitoring the current and predicting the near future signature. The output of such a system can subsequently be used for improved countermeasure deployment by linking it to an onboard Electronic Warfare Tactical Decision Aid (EWTDA). This paper addresses a methodology for evaluating the effect of different signature reduction measures on decoy effectiveness by using engagement simulations. The importance of the fidelity in background (e.g. clutter statistics) and ship signature modelling is also discussed. Finally, an example will be given of a concept signature monitoring system consisting of sensors and signature models which is currently being deployed on an operational Royal Netherlands Navy (RNLN) vessel. Future versions of this system are expected to provide input to the onboard EWTDA to enable more effective decoy deployments.