The Second United States Controlled Substances Intelligence Bureau (CSIB), under the U.S. Army, is a federal law enforcement agency primarily focused on the collection, analysis, and dissemination of intelligence related to illegal drugs. Established during the Vietnam War in the late 1960s as an expansion of the initial CSIB, its mission is to support military operations by providing timely and accurate information about drug trafficking activities affecting U.S. forces and national security. The bureau operates under the authority of the Department of Defense and collaborates with other domestic and international law enforcement agencies in their efforts to combat illicit drugs.