Intelligence_ From Secrets to Policy - Mark M. Lowenthal [67]
The ability to intercept communications is highly important, because it gives insight into what is being said, planned, and considered. It comes as close as one can, from a distance, to reading the other side’s mind, a goal that cannot be achieved by imagery. Reading the messages and analyzing what they mean is called content analysis. Tracking communications also gives a good indication and warning. As with imagery, COMINT relies to some degree on the regular behavior of those being watched, especially among military units. Messages may be sent at regular hours or regular intervals, using known frequencies. Changes in those patterns—either increases or decreases—may be indicative of a larger change in activity. Monitoring changes in communications is known as traffic analysis, which has more to do with the volume and pattern of communications than it does with the content. (See box, “SlGlNT Versus IMINT.”) One other important aspect of COMINT is that it provides both content (what is being said) and what might be called texture, meaning the tone, the choice of words, the accent (such as when distinguishing one type of French- or Spanish- or Arabic-speaker). Texture is like listening to the tone or watching the facial expression of a speaker. This can tell you as much—or sometimes more—as the words.
SIGINT VERSUS IMINT
An NSA director once made a distinction between IMINT—now called GEOINT—and SIGINT: “IMINT tells you what has happened; SIGINT tells you what will happen.”
While an exaggeration—and said tongue in cheek—the statement captures an important difference between the two collection disciplines.
COMINT has some weaknesses. First and foremost, it depends on the presence of communications that can be intercepted. If the target goes silent or opts to communicate via secure landlines instead of through the air, then the ability to undertake COMINT ceases to exist. Perhaps the landlines can be tapped, but doing so is a more difficult task than remote interception from a ground site or satellite. The target also can begin to encrypt— or code—its communications. Within the offensive-defensive struggle over SIGINT is a second struggle, that between encoders and codebreakers, or cryptographers. Crypies, as they are known, like to boast that any code that can be constructed can also be solved. But the present-day is far removed from the Elizabethan age of relatively simple ciphers. Computers greatly increase the ability to construct complex, onetime-use codes. Meanwhile, computers also make it more possible to attack these codes. Finally, the target can use false transmissions as a means of creating less compromising patterns or of subsuming important communications amid a flood of meaningless ones—in effect, increasing the ratio of noise to signals.
Another issue is the vast quantity of communications now available: telephones of all sorts, faxes, e-mails, and so on. In 2002, for example, there were some 180 billion minutes of international phone conversations, from some 2.8 billion cellular phones and 1.2 billion fixed phones. Instant messaging, a relatively new medium, generates 530 billion messages daily. As communications switch to fiber optic cable, the available volume will increase. Also, more phone calls are going over the Internet using the Voice-over-Internet-Protocol (VoIP) technology.
Even a focused collection plan collects more COMINT than can be processed and exploited. One means of coping with this is the key-word search, in which the collected data are fed into computers that look out for specific words or phrases. The words are used as indicators of the likely value of an intercept. The system is not perfect, but it provides a necessary filter to deal with the