The laser is an integrated part of many weapon systems, such as laser guided bombs, laser guided missiles and laser beam-riding missiles. These systems pose a significant threat to military assets on the modern battlefield. The lasers used in beam-riding missiles are particularly hard to detect as they typically use relatively low power lasers. Beamriders are also particularly difficult to defeat as current countermeasure systems have not been optimized against this threat. Some recent field trails conducted in the United Arab Emirates desert have demonstrated poor performance of both laser beam-riding systems and the LWRs designed to detect them. The aim of this research is to build a complete evaluation tool capable of assessing all the phases of an engagement of a main battle tank or armoured fighting vehicle with a laser based guided weapon. To this end a software model has been produced using Matlab & Simulink. This complete model has been verified using lab based experimentation and by comparison to the result of the mentioned field trials. This project will enable both the evaluation and design of any generic laser warning receiver or missile seeker and specific systems if various parameters are known. Moreover, this model will be used as a guide to the development of reliable countermeasures for laser beam-riding missiles.