 The black helicopters theory resonates well with the belief held by some in the militia movement that troops from the United Nations might invade the United States.The John Birch Society published an article in "The New American" detailing how the existence of the covert aircraft was mostly the product of possible visual errors and a tendency towards overabundant caution.The following organizations and government agencies are known to operate black and/or unmarked helicopters in the United States for unclassified uses