What initiates the operation of the IFF system?

The operation of the IFF (Identification Friend or Foe) system is initiated by the interrogator. This device is responsible for sending a specific signal that prompts transponders located on friendly aircraft or vessels to respond with an identification reply. The interrogator plays a crucial role in the process as it actively seeks out responses from transponders to distinguish between friendly and potentially hostile forces.

While the transponder is essential in the communication process by sending back the identification code, it requires the signal from the interrogator to initiate its response. The control panel and communication devices are involved in setting up the system or relaying information, but they do not directly trigger the identification process. Therefore, the interrogator's role is pivotal in the functioning of the IFF system, making it the correct answer.