This paper investigates the defensive counterspace function as defined in Air Force Doctrine Document 1 and considers whether an on-orbit capability is needed for its fulfillment. The discussion begins with the examination of threats to space systems, how they are likely to be attacked and the means with which to counter those attacks. The examination focuses on the space element and determines that a space-based defensive capability will be needed to protect orbital assets in the future. The defensive potential of ground-based systems and self-defending spacecraft are determined to be inadequate, leading to the conclusion that a dedicated, mission specific vehicle design is the best option for fulfilling the defensive counterspace function. Finally, preliminary considerations of vehicle design and mission capability indicate that the first iteration of this vehicle should be ground-stationed, reusable, and prepared to launch into earth orbit in time of heightened tensions or war to carry out the defensive counterspace mission.