1952
The Robertson Panel was a committee commissioned by CIA in 1952 in response to widespread Unidentified Flying Object reports, especially in the Washington D.C. area. The panel was briefed on U.S. military activities and intelligence; hence the report was originally classified Secret. See the more recent article Arthur C. Lundahl#Unidentified Flying Objects, which addresses discussions in 1967.
Read more about this topic: CIA Activities In The United States