Ultra High Frequency Follow-On (UFO) satellite system is a United States Department of Defense (DoD) program sponsored and operated by the United States Space Force to provide communications for airborne, ship, submarine and ground forces.

The ground terminal segment consists of equipment and resident personnel at existing satellite communication stations.

The Ultra high frequency (UHF) satellites primarily served tactical users.

[1] The solar panels spans 18.4 m (60 ft) and produces 2,500 watts at the end of the planned 14-year lifetime.

Block 2 satellites, starting with UHF 4, added extremely high frequency package with 11 channels.