The initial DSCS-I experiment was followed in February 1969 with the more ambitious Tactical Satellite Communications (TACSATCOM) program. This program was used to evaluate mobile user needs in tactical situations. One TACSATCOM satellite was placed in geostationary orbit to support the Tactical Communications Program. It was equipped with two transponders, one at X-band and one at UHF. The X-band transponder had a bandwidth of 10 MHz and a maximum RF power of 30 watts. The UHF transponder has a bandwidth of 10 MHz and a maximum RF output of 230 watts. Provision was made for cross strapping the UHF and X-band up and downlinks with a reduced useable bandwidth of 425 kHz. Earth coverage horn antennas were used at X-band, bifilar helices were used at UHF. About 100 terminals used the Ultra-High Frequency (UHF), and Super-High Frequency (SHF) bands (mostly UHF). They ranged from manpack size up to 1 1/4 ton vehicular equipment and also included airborne equipment.
In June 1970, residual IDCSP and TACSATCOM assets were made available to the United States (US) Navy by Joint Chiefs of Staff (JCS) direction, to provide an interim Operational Capability (IOC). This was followed by the approval of the Fleet Satellite Communications (FLTSATCOM) Program by the Secretary of Defense in September 1971. The TACSATCOM spacecraft (TACSAT-1), located in the Pacific Area failed in December 1972.