Submarine-launched ballistic missile

The submarine-launched ballistic missile (often abbreviated SLBM) is a world object in Fallout 4 and its add-on Far Harbor.

Background
The SLBM is designed to launch a nuclear payload from a submarine.

Yangtze
The Yangtze carried six SLBMs with high yield warheads on board in October 2077. She was in the vicinity of Boston when the Great War began, launching all but one, which failed to launch.

USS Democracy
The USS Democracy carried four SLBMs with high yield warheads on board in October 2077. Due to a firing system malfunction and a containment breach, only one of the missiles was launch capable. In the end, none of the missiles were launched, because the vessel's captain had gone missing, along with the nuclear launch key.