What is the classified military encrypted mode in IFF?

In the context of Identification Friend or Foe (IFF) systems, Mode 4 is specifically designated as the classified military encrypted mode. This mode employs a secure encryption scheme designed to prevent unauthorized interception and ensure that the signals can only be processed by friendly forces that have the appropriate decryption capabilities.

Mode 4 is critical in military operations as it allows for secure and reliable identification of friendly aircraft, which is essential for avoiding friendly fire incidents and enhancing operational safety. The encryption used in Mode 4 also contributes to maintaining the integrity of military communications and situational awareness in contested environments.

While other modes exist, such as Mode 1, Mode 2, and Mode 3, they are not encrypted or classified in the same way. Mode 1 and Mode 2 are typically used for non-secure identification purposes, while Mode 3 is the civilian mode widely recognized for air traffic control. Thus, Mode 4 stands out as the only mode that incorporates military-grade encryption for enhanced security.