- The rise of reports of "flying black triangles" may be explained by the "Have Blue" stealth fighter project of the USAF
- When civilians reported these black triangles, the USAF would deny they had planes in the air during that time
- One UFO skeptic claimed that many vintage UFO reports could be explained by experimental flights of the U-2 spy plane during the 60s
- UFO believers suspect that USAF is now experimenting with a new generation of stealth in a project called "Aurora"