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Signals intelligence (SIGINT)

[is] [t]he generic term used to describe communications intelligence and electronic intelligence when there is no requirement to differentiate between these two types of intelligence, or to represent fusion of the two.[1]
is intelligence-gathering by interception of signals, whether between people (i.e., communications intelligence (COMINT)) or between machines (i.e., electronic intelligence (ELINT)), or mixtures of the two.
[is] intelligence gathered from data transmissions, including Communications Intelligence (COMINT), Electronic Intelligence (ELINT), and Foreign Instrumentation Signals Intelligence (FISINT). SIGINT includes both raw data and the analysis of that data to produce intelligence.[2]
1. A category of intelligence comprising either individually or in combination all communications intelligence, electronic intelligence, and foreign instrumentation signals intelligence, however transmitted. 2. Intelligence derived from communications, electronic, and foreign instrumentation signals.[3]


[SIGNET] has two principal components. First, communications intelligence (comint) is derived from the interception and analysis of electromagnetic communications and data links. Second, electronic intelligence (elint) collects and analyses non-communication emissions such as those used in radar detection, rocket telemetry and nuclear testing. Today, technological and computational advances create innumerable opportunities for the interception of diplomatic, military, scientific and commercial communications, as well as the extrapolation of radar, spacecraft and weapons systems characteristics.[4]

As sensitive information is often encrypted, signals intelligence often involves the use of cryptanalysis. However, traffic analysis — the study of who is signalling whom and in what quantity — can often produce valuable information, even when the messages themselves cannot be decrypted.

Pursuant to Executive Order 12333, as amended, the Secretary of Defense serves as the Executive Agent for SIGINT and the Director of the National Security Agency (NSA) serves as Functional Manager for SIGINT and National Manager for National Security Systems.

SIGNIT operations are classified, but there is little doubt that the need for intelligence on a growing variety of nations and groups that are increasingly using sophisticated and rapidly changing encryption systems requires a far different SIGNIT effort than the one prevailing during the Cold War. Since the late 1990s a process of change in NSA's culture and methods of operations has been initiated, a change required by the need to target terrorist groups and affected by the proliferation of communications technologies and inexpensive encryption systems.


  1. NATO Standardization Agency, NATO Glossary of Terms and Definitions 2-S-7 (2008) (full-text).
  2. U.S. National Intelligence: An Overview 2011, at 55.
  3. Electronic Warfare, at GL-13.
  4. Canadian International Council, "Canada and the Five Eyes Intelligence Community" (Dec. 18, 2012) (full-text).

See also[]

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