COMINT or Communications Intelligence refers to any intelligence gleaned by intercepting channels, such as text messaging, telephone, email, instant messaging, and other online and electronic means of communication. Armed forces used it in World War II and continue to do so as part of national security protection.

COMINT is part of a larger type of intelligence called “Signals Intelligence (SIGINT),” which is intelligence gathered through the interception of signals. Aside from COMINT, SIGINT also includes Electronic Intelligence (ELINT), a type of intelligence gained from intercepting electronic signals that are not necessarily used in communication.

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COMINT played a significant role in World War II and has become an integral part of almost every government’s security activities. In the U.S., SIGINT (including COMINT and ELINT) is handled by the National Security Agency (NSA).

What Role Did COMINT Play in World War II?

COMINT processing centers were established in Guam, Hawaii, and the Philippines at the beginning of the war, even though the tactic was still new at that time. While some were skeptical, COMINT proved useful on 24 April 1942, when the Navy Radio Intelligence Section (known as “OP-20-G”) intercepted the following message:

Change #3 Truk Communication Section, for Naval call list #117, on 25 April page 5 between Kana 1 and Kana 6 insert the following in order:

Kana 1 MO Fleet

Kana 2 MO Occupation Force

Kana 3 MO Occupation Force —-

Kana 4 MO Attack Force —-

Kana 5 RZP Occupation Force

Kana 6 MO Occupation Force

Kana 7 RXB Occupation Force

Kana 8 RY Occupation Force

MO WI #—- Force of the 3rd Special Base Force

I NE #—-Force of the 5th Special Base Force

The analysis of this intelligence enabled the Commander-in-Chief of the Pacific Fleet to anticipate the planned Japanese offensive sometime in early May. After processing more intelligence, they were able to send advance forces on 29 April. The resulting battle caused significant damage to the Japanese, partially paralyzing them during the infamous Battle of Midway.

What Is the Difference between COMINT, SIGINT, and ELINT?

SIGINT is the umbrella term for all intelligence gathered from signal interception. The intercepted signal could be a communication channel, which would fall under the COMINT subcategory. Other intercepted signals that are not necessarily involved in people’s communication fall under the ELINT subcategory.

What Are Examples of COMINT Techniques?

The core target of COMINT is communication between people. As such, most of the COMINT techniques involve any means of communication, including:

  • Voice Interception: You might already be familiar with this technique since wiretapping has made headlines in the past years. Voice interception is a fundamental COMINT technique, requiring specialists to listen to leaks in voice communications via radio, telephone, and cellular network. Aside from leaks, specialists may also employ wiretapping to intercept voice communications. 
  • Signal Interception: Sometimes, COMINT specialists intercept the signaling channel instead of a specific voice communication channel. This COMINT technique allows units to access the whole digital signal link carrying countless voice communications.
  • Text Interception: Several technologies allow even governments, cyber attackers, and regular people to intercept text messages. In national security, armed forces focus more on intercepting cryptography than the usual text messages sent by one individual to another.

Does COMINT Focus Only on Foreign Communications?

While COMINT is heavily associated with intercepting foreign communications to strengthen national security, SIGINT or COMINT units may also listen in on friendly communication channels. This vertical is essential because some members of an organization could be relaying critical information over an unsecured or inappropriate network. These costly and dangerous mistakes can be abruptly detected and mitigated by listening to friendly communications.

A few nations are working together to support each other’s communication security as part of the BREADWINDOW procedures, a set of guidelines that focus on Essential Elements of Friendly Information (EEFIs). Some countries that use the BREADWINDOW procedures and codes are Australia, Canada, New Zealand, the U.K., and the U.S.

COMINT brought about several moral, legal, and ethical issues. Should the government listen in on its citizens’ communications? The answer could depend on your views and beliefs. However, what we know from history is that COMINT has been helpful to countries’ armed forces.