What is the sole mission and fundamental reason for the existence of the fleet ballistic missile submarine?

The fundamental mission of the fleet ballistic missile submarine (FBM) is to deter war through the capability of nuclear retaliatory strikes. This ability is rooted in the concept of mutually assured destruction, where the existence of a strong nuclear deterrent prevents potential adversaries from engaging in aggressive actions that could escalate into full-scale conflict. The submarines are designed to remain hidden and resilient, ensuring they can carry out their mission even in times of heightened tension or warfare.

While projecting power, supporting naval operations, and gathering intelligence are important functions of various naval assets, they are not the core purpose of the fleet ballistic missile submarine. Their primary role focuses on strategic deterrence, specifically through the launch of ballistic missiles in response to nuclear threats, thereby maintaining a stable balance of power. This specialized mission underscores the significance of these submarines in national defense policy and global security dynamics.