Foreign instrumentation signals intelligence

Foreign Instrumentation Signals Intelligence (FISINT) is a subset of signals intelligence (SIGINT) that specifically focuses on the collection, analysis, and exploitation of signals emitted by foreign instrumentation systems. These systems may include telemetry, targeting, and other types of signals used in the testing and operation of military systems, such as missiles, rockets, and aircraft. FISINT allows intelligence agencies to gather information about foreign weapon systems' capabilities and performance by intercepting and analyzing the signals they emit.