MILSTAR (Military Strategic and Tactical Relay) is a U.S. joint service satellite communications system that provides secure, jam resistant, worldwide communications to meet essential wartime requirements for high priority military users. The multi-satellite constellation links command authorities with a wide variety of resources, including ships, submarines, aircraft and ground stations.

The MILSATCOM Joint Program Office administers MILSTAR, and day to day operations and maintenance are conducted by the 4th Space Operations Squadron at Schriever AFB, Colorado, USA.

Satellites in the MILSTAR constellation are in geostationary orbits. Each weighs approximately 10,000 pounds and has a design life of 10 years.

The first Milstar satellite was launched Feb. 7, 1994 aboard a Titan IV expendable launch vehicle.