Milstar is a joint service satellite communications system that provides worldwide secure, jam resistant and low probability of detection nuclear-event resistant communications for all forces across the spectrum of conflict. The multi-satellite constellation will link command authorities with a wide variety of resources, including ships, submarines, aircraft, land vehicles and manned-portable systems.

Each Milstar satellite serves as a switchboard in space directing traffic from terminal to terminal anywhere on Earth. Since the satellite processes the communications signal and can link with other satellites through crosslinks, the requirement for ground controlled switching is significantly reduced. The satellite establishes, maintains, reconfigures and disassembles required communications circuits as directed by the users. Milstar terminals provide encrypted voice, data, teletype, or facsimile communications. Milstar provides interoperable communications among users of Army, Navy, and Air Force Milstar terminals. Geographically dispersed mobile and fixed control stations provide survivable and enduring operational command and control for the Milstar constellation.

The MILSTAR uplink/downlink frequency is 44/20 GHz.