Project Horizon was a 1959 study to determine the feasibility of constructing a scientific / military base on the Moon, at a time when the U.S. Department of the Army, Department of the Navy, and Department of the Air Force had total responsibility for U.S. space program plans. On June 8, 1959, a group at the Army Ballistic Missile Agency (ABMA) produced for the Army a report titled Project Horizon, A U.S. Army Study for the Establishment of a Lunar Military Outpost. The project proposal states the requirements as:
The lunar outpost is required to develop and protect potential United States interests on the moon; to develop techniques in moon-based surveillance of the earth and space, in communications relay, and in operations on the surface of the moon; to serve as a base for exploration of the moon, for further exploration into space and for military operations on the moon if required; and to support scientific investigations on the moon.[1]
The permanent outpost was predicted to be required for national security "as soon as possible", and to cost $6 billion. The projected operational date with twelve soldiers was December 1966.
Horizon never progressed past the feasibility stage, being rejected by President Dwight Eisenhower when primary responsibility for America's space program was transferred to the civilian agency NASA.[2]
https://en.wikipedia.org/wiki/Project_Horizon
https://nsarchive2.gwu.edu/NSAEBB/NSAEBB479/docs/EBB-Moon01_sm.pdf