six o'clock
Not a second late . The first of the hydrogen missiles , launched from the Council buildings on the other side of the world , were beginning to arrive . The attack had begun . At exactly six o'clock Joseph Dixon , standing on the surface four miles from the entrance tunnel , gave the sign to the waiting units . The first job was to break down Sherikov 's defense screens . The missiles had to penetrate without interference . At Dixon 's signal a fleet of thirty Security ships dived from a height of ten miles , swooping above the mountains , directly over the underground laboratories .