UFOs have been subject to investigations over the years that varied widely in scope and scientific rigor. Governments or independent academics in the United States, Canada, the United Kingdom, Japan, Peru, France, Belgium, Sweden, Brazil, Chile, Uruguay, Mexico, Spain, and the Soviet Union are known to have investigated UFO reports at various times.
Among the best known government studies are the ghost rockets investigation by the Swedish military (1946–1947), Project Blue Book, previously Project Sign and Project Grudge, conducted by the United States Air Force from 1947 until 1969, the secret U.S. Army/Air Force Project Twinkle investigation into green fireballs (1948–1951), the secret USAF Project Blue Book Special Report #14 by the Battelle Memorial Institute, and Brazilian Air Force Operation Saucer (1977). France has had an ongoing investigation (GEPAN/SEPRA/GEIPAN) within its space agency CNES since 1977; the government of Uruguay has had a similar investigation since 1989.
Read more about this topic: Unidentified Flying Object