Below is a highly redacted, but still provides the broad outlines of policy and history of the NSA/US Navy’s Technical Research Ship Program written by Ms. Julie Alger. The history which, according to its preface, was written in early Spring 1970, is an early account of the NSA/US Navy’s Technical Research Ship Program. These ships were floating SIGINT/COMINT/ELINT(1) platforms that collected intelligence from hostile targets by trawling off-shore and scooping up whatever intelligence they could gather. The most famous of these was the USS Liberty which was attacked and nearly sunk by Israeli forces during the Six-Day-War. The USS Pueblo, seized by North Korean forces in 1968, is not mentioned in this report, but was a ship of similar function for a US Navy only program.
NSA Technical Ship Paper
(1) SIGINT= Signals Intelligence/ COMINT = Communications Intelligence/ ELINT = Electronics Intelligence