Between 1952-1969, the United States Air Force were conducting a study into UFO sightings. One year after it was started, the United States Director of Central Intelligence, Walter B Smith, detailed (in a now declassified document) how UFO could be used as ‘psychological warfare’.
I think this was potentially when the concept of a fake alien invasion was initially considered by the ‘powers that be’ as a way to bring the worlds countries together with the final objective to usher in a New World Order.
The declassified documents of Project Blue Book, can be found below.
“Project Blue Book was the code name for the systematic study of unidentified flying objects by the United States Air Force from March 1952 to its termination on December 17, 1969. The project, headquartered at Wright-Patterson Air Force Base, Ohio, was initially directed by Captain Edward J. Ruppelt and followed projects of a similar nature such as Project Sign established in 1947, and Project Grudge in 1948. Project Blue Book had two goals, namely, to determine if UFOs were a threat to national security, and to scientifically analyze UFO-related data.” – Wikipedia
Declassified documents regarding Project Blue Book can be found here by clicking this link.