Army Field Manual 2 22.3, or FM 2-22.3, Human Intelligence Collector Operations, was issued by the Department of the Army on September 6, 2006.

The United States is widely considered to have one of the most extensive and sophisticated intelligence network of any nation in the world, with organizations including the Central Intelligence Agency and the National Security Agency, amongst others.

The German Radio Intelligence Operation were signals intelligence operations that were undertaken by German Axis forces in Europe during World War II.