Declassified CIA documents reveal the US government was assessing the possibility of an alien invasion during the 1950s and 60s.
The first well-known sighting of an unidentified flying object (UFO) can be traced back to 1947, when businessman Kenneth Arnold claimed to see a number of 'flying saucers' in Washington State.
While UFO obsessions persists to this very day, sightings have spiked at different points in history.
According to various declassified documents shared via UFO advocacy group Disclosure Party, abnormal numbers of reports during the 50s and 60s prompted a joint venture from the US and Australian governments to assess extraterrestrial reports.
The 58-page document, shared by the National Archives of Australia, states the project ran from 1957 until 1971, and evaluated the likelihood of an alien invasion.
This research ran alongside a similar time to 'Project Blue Book', a study of UFOs by the US Air Force that began in 1952, following a bunch of sightings in the skies above Washington D.C.
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