Pearl Harbor Revisited: United States Navy Communications Intelligence, 1924-1941

Chapter 1. Pearl Harbor Revisited: United States Navy Communications Intelligence 1924–1941

"The aspect of the Pearl Harbor disaster which is really surprising is that so many people failed to do either the obvious or the sensible things." Washington Star, 1 September 1945

INTRODUCTION

This is the story of the U.S. Navy's communications intelligence (COMINT) effort between 1924 and 1941. It traces the building of a program, under the Director of Naval Communications (OP-20), which extracted both radio and traffic intelligence from foreign military, commercial, and diplomatic communications.^[1] It shows the development of a small but remarkable organization (OP-20-G) which, by 1937, could clearly see the military, political, and even the international ...