Article

The US Air Force shifted from the canceled Advent satellite program to the Initial Defense Satellite Communications System (IDSCS) in the 1960s, focusing on multiple medium-altitude satellites. By 1968, 35 satellites were operational in near-synchronous orbits, enhancing military communication, especially in Vietnam.

The IDSCS allowed direct links from Saigon to Washington, DC, and supported projects like Compass Link for high-resolution photography transmission. Designed as an interim solution, IDSCS led to the development of the larger Defense Satellite Communications System II (DSCS II) targeting improved capabilities in geosynchronous orbit.