Prior to the Environmental Modification Convention signed in Geneva in 1977, the United States used weather warfare in the Vietnam War. Operation Popeye saw the use of cloud seeding over the Ho Chi Minh trail. It was hoped that the increased rainfall would reduce the rate of infiltration down the trail.[1]A research paper produced for the United States Air Force written in 1996 speculates about the future use of nanotechnology to produce “artificial weather”, clouds of microscopic computer particles all communicating with each other to form an “intelligent fog” that could be used for various purposes. “Artificial weather technologies do not currently exist. But as they are developed, the importance of their potential applications rises rapidly.”