The role of robust communications plays an ever pervasive and critical role in today's network-oriented asymmetric warfare. This is especially true in urban environments, where insurgencies tend to be most active and detrimental to the civilian population. Urban-level communications needs to be addressed through a new generation of modeling and simulation tools that not only model the physical layers of radio communications, but that also account for reactive network behaviors that drive higher-level force actions (e.g., the interplay of ground troops, ground vehicles, airborne UAVs, manned aircraft, etc.) Such tools should become essential to communications mission planning, while advancing the deployment of optimally designed communications systems for use in highly complex RF environments. To this end, we describe the Scalable Urban Network Simulation (SUNS), which coordinates physical layer EM propagation modeling with network-level and higher "forces level" modeling to achieve a highly interactive, "full communications stack" approach to network simulation.