signals intelligence (SIGINT): 1. A category of intelligence comprising, either individually or in combination, all communications intelligence, electronics intelligence, and foreign instrumentation signals intelligence, however transmitted. [JP 1-02] 2. Intelligence derived from communications, electronics, and foreign instrumentation signals. [JP 1-02]
SIGINT
SIGINT is actually a broad discipline under which multiple sub-disciplines fall. There are three major sub-disciplines that fall under SIGINT which are COMmunications INTelligence (COMINT), ELectronic INTelligence (ELINT), and Foreign Instrumentation Signals INTelligence (FISINT). It should be noted that COMINT is commonly referred to as SIGINT, which can cause confusion when talking about the broader intelligence disciplines.
SIGINT became far more central to military (and to some extent diplomatic) intelligence generally with the mechanization of armies, development of blitzkrieg tactics, use of submarine and commerce raiders warfare, and the development of practicable radio communications. For example, failure to properly protect its communications fatally compromised the Russian Army in its advance early in WWI and led to their disastrous defeat by the Germans under Ludendorff and Hindenburg at the Battle of Tannenberg. Similarly, the interception and decryption of the Zimmerman telegram was an important factor in the US decision to enter the War.
On the negative side, the inability of British commanders to take seriously traffic analysis information from intercepts was instrumental in the failure to achieve more than they did at the Battle of Jutland, thus losing what might have been a major opportunity.
The use of SIGINT had important implications during WWII as well. Early on, Admiralty dismissal of SIGINT information (also traffic analysis in this instance) contributed to the loss of HMS Glorious in 1940. The Allied ability to intercept and decrypt the German Enigma "E Traffic" and Japanese Purple (Magic) traffic proved to be a great military advantage. The combined effort of intercepts and cryptanalysis for the whole of the British forces in WWII came under the code name (Ultra) controlled from Station X (Bletchley Park). Perhaps most dramatically, intercepts of Japanese naval communications yielded information that gave Admiral Nimitz the upper hand in the ambush that resulted in the Japanese Navy's defeat at the Battle of Midway, six months after the Pearl Harbor disaster.
As sensitive information is often encrypted, SIGINT often involves the use of cryptanalysis. However, traffic analysis--the study of who is signalling who and in what quantity--can often produce valuable information, even when the messages themselves cannot be decrypted.
Intelligence derived from any of the SIGINT disciplines are very sensitive due to the ability to determine the source of the information. By determining the source of the intelligence information, the enemy can deny access or even send deceptive information to confuse and otherwise reduce the trustworthiness of the information.
The UKUSA Community is an alliance of English-speaking nations led by the United States and United Kingdom for the purpose of gathering intelligence via signals intelligence.
The UKUSA constituent agencies are:
Australia - Defence Signals Directorate (DSD)
Canada - Communications Security Establishment (CSE)
New Zealand - Government Communications Security Bureau (GCSB)
United Kingdom - Government Communications Headquarters (GCHQ)
United States - National Security Agency (NSA)
One role of the UKUSA Community is to service the ECHELON system. (now dont take the echelon concept too seriously)
http://www.tscm.com/cseukusa.html (great reading about the ukusa community)
If you have any questions regarding sigint and how canada is involved and it's different departments entities and such, just ask, I did some extensive research and studies in that deparment, also I did my QL3 as a comm rsch (bailed out a few weeks before grad) with ex-fusiller.