Why are ocean surveillance ships not normally armed or permanently escorted?
Short answerThey operate behind layered defenses and can receive an escort when required, while nearby anti-submarine forces protect them against the likeliest threat.
NotesOcean surveillance ships are intended to work far enough behind the fighting that organic armament offers limited value. An attacker must first penetrate several layers of friendly surveillance and protection. If commanders judge the threat high enough, an escort can be assigned quickly. During the Cold War, a submarine trying to close and attack such a ship would also risk being detected and prosecuted by nearby anti-submarine forces.