 His intent was not to propose that such a weapon be built, but to show that nuclear weapon technology would soon reach the point where it could end human life on Earth, a doomsday device.Such "salted" weapons were requested by the U.S. Air Force and seriously investigated, but not deployed.In the 1964 edition of the U.S. Department of Defense book "The Effects of Nuclear Weapons", a new section titled radiological warfare clarified the "Doomsday device" issue.