The ballistic-missile submarine

technology

The single technology that most changed the arithmetic of deterrence, because it made a retaliatory force that cannot be targeted. A nuclear-powered submarine carrying ballistic missiles does not need to surface, does not need to refuel, and can stay at sea for the length of a crew's endurance rather than a fuel supply; an adversary planning a first strike can count the other side's silos on satellite photographs but cannot know where the submarines are. That asymmetry is what makes disarming first strikes impossible in principle rather than merely difficult, and it is the reason the sea-based leg of both arsenals grew through the period while planners argued about everything else. The trade-offs are real: submarine-launched missiles were for a long time less accurate than land-based ones, and communicating a launch order to a submerged boat is a hard and slow problem, which is why command and control of the sea-based force is one of the least publicly documented parts of the whole system.

A technology is not a place. Drawing it on a map would assert something about the world that no stored fact supports.