Traffic analysis in the United States was created as a recognized discipline of signals intelligence (SIGINT) by the U.S. Navy during the period between World War and I and World War II.

The Japanese Grand Fleet Maneuvers of 1930 and 1933 provided the incentive and Lieutenant Joseph N. Wenger, USN (who served as first vice director of the National Security Agency in 1952-53), merits recognition as the instigator of traffic analysis activities during those times.

Part 1 of 6 CAPT Wenger
Lieutenant Joseph N. Wenger, pictured as a Captain

Naval maneuvers by the Japanese in 1930 astounded the U.S. in more ways than one: the exercises demonstrated a scope and depth of Japanese ambitions in the Pacific heretofore unimagined and shocked the Navy into realizing the necessity for tactical intelligence in support of the U.S. fleet. In 1933, Wenger and the Navy responded to the challenge. They recognized the need for immediate and accurate intelligence on the movement and actions of the Japanese navy.  It was Wenger’s perception that a study of the external features of radio traffic (a) could supply vital intelligence to the fleet even without a successful cryptanalytic breakout of the content of that traffic.

The Navy seized upon the Japanese maneuvers of 1933 to establish the value of radio traffic analysis to fleet operations. An experiment conducted during the maneuvers, focused on exploiting Japanese radio traffic, was imminently successful and was the single most important event in the development of traffic analysis for the United States between the wars. Wenger, one of the Navy’s first cryptanalysts, developed a plan in the spring of 1933 to exploit Japanese operational naval communications during the summer maneuvers. He developed rudimentary traffic analysis techniques which helped to identify and locate communications subscribers. This produced immediate intelligence. The development of traffic analysis during this period subsequently proved to be of inestimable value to the United States during World War II.

Source: NSA

Station HYPO note: (a) Also known as chatter or radio chatter.