British intelligence services pioneered SIGINT activities during World War I. In January 1917, British cryptographers who were members of “Room 40” managed to unravel a telegram from German Foreign Minister Arthur Zimmermann to the German Ambassador to Mexico Heinrich von Eckhardt sent via cable- submarine cable. The telegram contained a set of instructions that if the neutral US entered into the war on the Allies, von Eckhardt was asked to approach and offer the formation of a secret wartime alliance to Mexican President Venustiano Carranza. Germany promised to provide military and financial support to Mexico if it agreed to attack the US, and in return, Mexico was given the freedom to annex “lost territories in Texas, New Mexico, and Arizona.” von Eckhardt was also authorized to use the Mexicans as an intermediary to lure the Japanese Empire to join the German struggle. In late February 1917, the British leaked the telegram to the United States without revealing how the secret was obtained. Zimmermann’s telegram encouraged the US to become involved in World War I and change the course of history. Another major achievement was that US cryptographers successfully tapped Japan’s Purple Code before World War II. The ULTRA project developed by Allied intelligence was able to dismantle the highest-level encrypted communications of the German, Italian, and Japanese armed forces. This success contributed to the Allied victory in World War II.

SIGINT according to the National Security Agency or NSA is an intelligence category that collects information through the electromagnetic spectrum. Information is obtained from transmissions related to communications, radars, and weapons systems to complement other intelligence categories.


“The basic key to victory in modern warfare is to do well in electronic warfare …”

Kim Jong-Il

SIGINT consists of:

  1. Communications Intelligence (COMINT) which obtains information from communication devices such as radios or telephones
  2. Electronic Intelligence (ELINT) obtains information from non-communication transmitters, for example, radar. Radar is a system that detects the presence, distance, speed of aircraft, and ships, and other objects.
  3. Foreign Instrument Signals (FIS or FISINT) are sourced from foreign telemetry signals, such as satellites.
  4. Computer Network Exploitation (CNE) is the latest component that utilizes computer networks and the internet to support intelligence operations.

SIGINT can be strategic or tactical. Strategic SIGINT has the objective of intercepting and monitoring the entire equipment system, deployment of opposing forces; as well as providing advice regarding new techniques, tactics, and procedures. Tactical SIGINT aims at gathering information, intercepting, identifying locations and communication channels of opposing forces, electronic systems, and applications used by enemy military forces on the battlefield.

The SIGINT data collection method consists of 3 stages:

  1. Search is the first phase of the SIGINT data collection process by snooping on the enemy’s electronic activity in the electromagnetic spectrum. The aim is to detect and sort electromagnetic signals that attract attention. Several characteristics of the external signal being examined are frequency, modulation, and bandwidth. Bandwidth is the maximum data transfer rate of a network or internet connection, measuring how much data can be sent over a connection in a certain amount of time.
  2. Interception is the second phase of determining the fingerprint of a signal, the process of identifying the unique characteristics of an emitter’s spectrum. The identification process is also applied to individual types of equipment.
  3. Finding direction is the third phase to find information about the estimated location of emission originating from the emitter. The purpose of the discovery of the direction of the radio is to find a bearing line from each source of electromagnetic radiation using the radio wave propagation properties. Triangulation is used to find the position of the emitter accurately.

SIGINT illustrations

#indiachinastandoff
SIGINT’s image depicts the presence of large numbers of Chinese troops, exactly 24 hours after the deadly dispute between Indian troops and Chinese troops over an altitude of 4,300 meters in the Galwan river valley in the steep Ladakh region. Several soldiers involved in the dispute reportedly fell into the Galwan river that flows swiftly in sub-zero temperatures. This image provides speculation that the Chinese side had no plans to withdraw, and the number of troops increased after talks at the level of Lieutenant General from both sides on June 6, 2020.

Video: © Ankit Kumar via @PlanetLabs, news source: Shiv Aroor.



Sources:
Convergence Between Signals Intelligence and Electronic Warfare Support Measures, Zsolt Haig, 2014
https://www.history.com/news/what-was-the-zimmermann-telegram
https://www.britannica.com/topic/Ultra-Allied-intelligence-project
https://techterms.com/definition/bandwidth

Photo: Pixabay/Gordon Johnson