The colonel told the senator: "The Air Force is not conducting any weather modification and has no plans to do so in the future." In fact, the Pentagon has long been interested in using weather as a weapon of war. Attempts to steer hurricanes by spraying heat-robbing chemicals in their paths date from the 1950s. The recipe for creating "cirrus shields" was outlined in a 1996 US Air Force study subtitled "Owning the Weather by 2025." The report explained how "weather force specialists" were dispersing chemicals behind high-flying tanker aircraft in a process called "aerial obscuration."