BAE Systems Submarines, is a wholly owned subsidiary of BAE Systems, based in Barrow-in-Furness, Cumbria, England, and is responsible for the development and production of submarines.

The Dreadnought class is the future replacement for the Royal Navy's Vanguard class of ballistic missile submarines. Like their predecessors they will carry Trident II D-5 missiles. The Vanguard submarines entered service in the United Kingdom in the 1990s with an intended service life of 25 years. Their replacement is necessary for maintaining a continuous at-sea deterrent (CASD), the principle of operation behind the Trident system.