From Revolution to Reform: A Brief History of U.S. Intelligence

Although organized intelligence activity developed very slowly in America's first century, it has since grown dramatically in scope and complexity. Expanding U.S. security concerns prompted the creation of permanent intelligence organizations in the late 1800s, which would grow, albeit unevenly, into the precursor of the modern American intelligence system by World War II. That conflict produced an explosion in intelligence activity, but it was really the advent of the Cold War that created and shaped today's Intelligence Community. The intelligence challenges posed by the Soviet Union and its allies encouraged greater variety in both the technological means of acquiring information and the organizations established to manage them. This trend, combined with the continued importance of intelligence programs serving—and controlled by—specific government departments, produced an intelligence system lacking a strong center, which well before September 11, would lead to calls for major reform.