The United Kingdom proclaims a protectorate over Tonga.

A protectorate, in the context of international relations, is a state or dependent territory that foregoes an independent foreign policy in favour of alliance with a protecting power, normally in order to ensure its defence against regional aggressors. It is a dependent territory that enjoys autonomy over most of its internal affairs, while still recognizing the suzerainty of a more powerful sovereign state without being a possession. In exchange, the protectorate accepts treaty obligations which bind it to the protecting power in foreign policy. Protectorates are established formally by a treaty between the powers involved. Under certain conditions—as with Egypt under British rule (1882–1914)—a state can also be labelled as a de facto protectorate or a veiled protectorate.