Which of the following is not a subcategory of SIGINT?

The identification of which option does not belong to the subcategories of SIGINT is rooted in an understanding of what SIGINT encompasses. SIGINT, or signals intelligence, primarily deals with the interception and analysis of signals for intelligence purposes.

COMINT, or communications intelligence, involves gathering intelligence from intercepted communications, which is a core aspect of SIGINT. ELINT, or electronic intelligence, refers to the collection of information from non-communication signals, such as radar and other electronic emissions. FISINT, or foreign instrumentation signals intelligence, specifically targets signals from foreign weapon systems and their use, fitting neatly within the SIGINT umbrella.

In contrast, HUMINT, which stands for human intelligence, involves gathering information from human sources rather than signals. This makes HUMINT distinct from SIGINT and its subcategories, as it relies on interpersonal relationships and human interactions rather than technological interception of signals. This fundamental difference in the nature of the information gathered highlights why HUMINT is not categorized under SIGINT.