The United States and New Zealand both share a treaty with Australia to cooperate on worldwide military matters.
The Australia , New Zealand , United States Security Treaty ( ANZUS or ANZUS Treaty ) is the 1951 collective security agreement which binds Australia and New Zealand and , separately , Australia and the United States , to co-operate on military matters in the Pacific Ocean region , although today the treaty is taken to relate to conflicts worldwide . United States . The Spanish -- American War and confirmed the country 's status as a global military power .