A state's need for a navy is distinct from the purposes it might want one to serve. Exposed sea lines of communication, maritime internal transport, fisheries protection, and attacks by pirates or other non-state actors can all create a defensive requirement. The early Royal Navy's Western Squadron shows how a force later valued for war fighting could begin as protection against coastal raiding. Some early European and Chinese fleets also existed primarily to supply and move land forces, with combat power as a secondary benefit.
Notable Point · 3:26-6:32
Defensive reasons to maintain a navy
Trade, fisheries, anti-piracy patrols, and moving land forces by sea can make naval power a practical defensive necessity.