What is a requirement when communicating with military aircraft operating under IFR?

When communicating with military aircraft operating under IFR, the requirement to relay official FAA messages as required is essential because it ensures that all operational information, including clearances, instructions, and safety advisories, is properly conveyed and acknowledged. This maintains a high level of safety in the airspace, especially since military aircraft may not always be familiar with civilian procedures and air traffic control (ATC) protocol.

Providing official FAA messages allows for the synchronization of information and assures that all parties involved are aware of any airspace restrictions, traffic advisories, or changes in flight status that might affect operations. It fosters a cooperative environment between military and civilian aviation, helping to prevent misunderstandings that could lead to safety hazards or operational inefficiencies.

In the context of the other choices, relaying operational information only during emergencies would limit critical communication that may be needed for routine operations. Avoiding communication unless necessary could lead to gaps in vital information sharing. Notifying the military command may be relevant in certain contexts, but it does not directly address the requirement for communication with regard to operational messages from the FAA.