New Zealand is officially responsible for the defence and foreign affairs of the Cook Islands and Niue. The Act of the New Zealand Parliament which established self-governance mentions a role for New Zealand, but the
Constitution of the Cook Islands does not. However, these responsibilities confer New Zealand no rights of control and can only be exercised at the request of the Cook Islands and Niue. The Cook Islands and Niue have been recognised as
sovereign states by some countries, and maintain diplomatic relations under their own name. The United States recognises the Cook Islands as a sovereign and independent state, and has signed treaties with the Cook Islands government. Moreover, the Secretary General of the
United Nations has determined that the admission of the Cook Islands and Niue into the
World Health Assembly means that they have been accepted as states by the international community. Although the Cook Islands and Niue behave as sovereign states in
international law, their constitutional statuses within the Realm of New Zealand (i.e., for matters of New Zealand
domestic law) is different from that of a fully independent state, considering that all of Niue's and the Cook Islands' nationals are automatically
New Zealand citizens, and both have New Zealand's
Monarch as their own head of state. While both the
Cook Islands and Niue have expressed a desire to become a UN member state, New Zealand has said that they would not support the application without a change in their constitutional relationship, in particular their right to New Zealand citizenship. However, New Zealand has never formally opposed such an application, nor has it argued that either country would not be within its sovereign right to do so. The foreign minister of Cook Islands has stated that a referendum would be required to determine whether to join the UN. In 2025, Cook Islands prime minister
Mark Brown stated that the UN had confirmed that the Cook Islands did not meet the requirements for UN membership. Additionally, in response to a push to introduce Cook Islander passports and agreements made with China, a spokesperson for New Zealand foreign minister
Winston Peters stated, "Unlike
Samoa,
Tonga and
Tuvalu, the Cook Islands is not a fully independent and sovereign state", unless its status and relationship with New Zealand are changed by
referendum. Some scholars have argued that a lack of separate Cook Islands citizenship places an effective limit on the ability of the Cook Islands to act as a sovereign entity, while others have argued that the participation of the Cook Islands in international organisations (such as the
Pacific Islands Forum) shows that Cook Islands sovereignty is not limited by the free association arrangement. == History ==