Perimeter greatly reduced the pressure to launch on warning at the first sign of an American attack. It gave Soviet leaders more time to investigate the possibility of a false alarm, confident that a real attack would trigger a computer-controlled, devastating response. But it rendered American plans for limited war meaningless; the Soviet computers weren't programmed to allow pauses for negotiation. And the deterrent value of Perimeter was wasted. Like the doomsday machine in Dr. Strangelove, the system was kept secret from the United States.