Video: 'NATO 60th Anniversary: 1949 Footage of the Original Signing Session of the North Atlantic Treaty'

(Monday, April 4, 1949, 4:30 p.m. EST; during the Cold War) — 12 nations, including the United States, signed the North Atlantic Treaty today at the Departmental Auditorium in Washington, D.C., by a committee chaired by U.S. diplomat Theodore Achilles.

The treaty formed the legal basis of, and is implemented by, the North Atlantic Treaty Organization (NATO), an intergovernmental military alliance whereby its independent member states agree to mutual defense in response to an attack by any external party.