The United States Air Force Security Service (often abbreviated USAFSS) was essentially the United States Air Force's cryptographic intelligence/Signals Intelligence (SIGINT) branch; its motto was Freedom through Vigilance. It was created in October 1948 and operated until 1979, when the branch was re-designated the Electronic Security Command.
Composed primarily of airmen selected from the cream of the Air Force's enlisted recruits (the top 1/2 of 1 percent), the USAFSS was a secretive and tight-knit branch of Air Force cold warriors tasked with monitoring, collecting and interpreting military voice and electronic signals of countries of interest (which often were Soviet and their satellite Eastern bloc countries). USAFSS intelligence was often analyzed in the field, and the results transmitted to the National Security Agency for further analysis and distribution to other intelligence recipients.
Individual airmen, stationed at locations scattered across the globe, did a variety of jobs, almost all of them related to listening to and interpreting Eastern Bloc, Communist Chinese, and North Vietnamese military communications. Some airmen were linguists who listened to voice communications. Others - known as Morse intercept operators, or "ditty-boppers" - monitored Soviet and other nations' military Morse code broadcasts. Others (that would be me), such as non-Morse intercept operators, were engaged in monitoring other types of radio signals such as single and multi-channel radio printer signals and facsimile transmissions. All communications were reviewed and interpreted by analysts.
These jobs, which required top secret code word clearance, were extremely high pressure and were considered essential to U.S. Cold War efforts. Members of the USAFSS were not allowed to discuss their jobs with outsiders—in fact, USAFSS members could not talk amongst themselves about their jobs unless they were in a secure location. Because of their value as targets (in Cold War Berlin, the capture of a USAFSS member was worth several thousand dollars), their off-base travel was severely restricted.
The activities of the USAFSS were declassified in 1997.
(Excerpts taken from https://en.wikipedia.org/wiki/United_States_Air_Force_Security_Service)