Because men know nothing about the possibility of gravity control they began to look toward the reaction propulsion known as rocketry as the only practical and attainable means of flight in space.
As usual in Earthly affairs the first large rockets were used as instruments of destruction and most of those now being built are especially designed and built for that purpose.
The present rockets together with the nuclear warheads they are designed to carry could quickly decimate the entire population of the planet.
From "The White Sands Incident" by Dr. Daniel Fry