ABSTRACT
Signals intelligence (SIGINT) is defined by the Department of Defense as "intelligence comprising, either individually or in combination, all communications intelligence, electronic intelligence, and foreign instrumentation signals, however transmitted". It consists of three components: communications intelligence (COMINT), electronic intelligence, and foreign instrumentation signals intelligence. Communications or signals transmitted via cable cannot be snatched out of the air and do not leak out into space. The United States (US) targets communications between different components of a large number of governments and organization. The communications of terrorist groups, particularly al-Qaeda, have been an important target of US COMINT efforts. Starting in the late 1940s, the US began establishing ground stations from which to monitor the Soviet Union and Eastern Europe. The network changed composition over the years and grew to include stations targeting China, Vietnam, North Korea, the Middle East, Central America, and other areas. The US has employed surface ships for the collection of SIGINT against both land- and sea-based targets.
