This presentation will highlight the importance of combining cyber and physical models in a virtual environment to benefit resiliency studies. The presentation will also explore specific use cases for when physical behaviors impact the cyber domain, when cyber actors can impact the physical domain, and the value of the virtual environment to explore these scenarios. Lastly, the presentation will discuss some risks of virtualizing non-COTS hardware, and some approaches to mitigate these risks. Software Defined Infrastructures (SDIs) provide researchers the opportunity to create, control, and maintain virtual architectures that can mirror physical, operational environments. There are several on-going efforts that have started to incorporate physics-based models and simulations to allow for accurate representation of satellites or aircraft in the virtual environment as well. Such an environment can play a key role during the architectural and design phases of an acquisition due to the ability to conduct a variety of trade studies early in the life cycle, and this exploration is vital to properly balance specialization vs. generalization of subsystem functions. Trade studies can start to unravel which subsystems require resiliency, how much resiliency is value-added, and what the impact is to mission. As the hardware design starts to mature, the use of a cyber-physical virtual twin that can interact and collaborate with its physical counterpart provides even more value. This is the value proposition for cyber-physical digital twins, since this real-time connection with the physical system provides value during development, manufacturing, production, operation, maintenance, and even disposal. In modern military terms, resilience is defined as robustness that is achieved through thoughtful, informed design that makes systems both effective and reliable in a wide range of contexts. Pursuit of resilient systems, however, necessarily involves the design of complex systems that successfully balance subsystem implementations that span the spectrum of implementation: specialization thru generalization. The promise of resilient systems can be more readily achieved through the use of cyber physical digital twins because the virtual environment provides opportunities to tailor the fidelity of the analysis and focus on the risk areas of most importance. This presentation will demonstrate examples of tailoring the fidelity of space-ground communication links and interactive command-and-control with virtual spacecraft.