Laser assisted micro milling (LAMM) is capable of generating three dimensional microscale features in hard metals with lower cutting forces than conventional micro milling. To maximize the reduction in cutting forces, a mathematical model is required to understand the influence of different laser and machining parameters on the forces. Consequently, a physics-based force model is developed in this paper to predict the cutting forces when micro milling a hard metal using laser assist. LAMM experiments are carried out on 52,100 bearing steel (62 HRc) over a range of feed rates and laser powers to calibrate the force model. The results indicate that the model predicts the cutting force profile with good accuracy. This model is then used to study the influence of laser assist on cutting forces, which yields a better physical understanding of the LAMM process.