In military contexts, information and communication services are critical, relying on secure and robust infrastructures. However, current network architectures in defense are often static and inflexible. Software-Defined Networking offers significant advantages in terms of flexibility, agility, network management, and operational costs. These properties are essential in dynamic environments, and SDN technology can further enhance these benefits by incorporating Software-Defined Radio technologies, which are highly used in defense environments. Additionally, SDN networks can ensure redundancy and resilience against failures. The adoption of SDN facilitates the flexible integration of Quantum Key Distribution networks, which provide an inherently secure method for cryptographic key distribution across network nodes. However, current QKD implementations face limitations in scope and flexibility, as they are generally based on fixed, point-to-point connections and static infrastructure. Together, SDN and QKD present synergistic benefits: SDN enables a flexible QKD network with enhanced control and monitoring capabilities, while QKD ensures secure communication even against quantum threats within the SDN architecture. The DISCRETION project develops an SDN solution integrating QKD capabilities for secure communications, enhancing European defense capabilities through these advanced technologies. Cipher Machines within DISCRETION assure the red-black network segregation, an essential feature in military networks.This is provided by enabling real-time encryption and decryption using keys supplied by the SDN-QKD layer, alongside pre-shared keys. For mobility and tactical scenarios, SDR solutions are evaluated and incorporated into the SDN solution to support radio network segments and ensure secure communications in mobile contexts. The proposed DISCRETION solution was deployed at the REPMUS 2024 defense event, yielding notable results.