In 1985, tension developed between New Zealand and the US. The US had been declared a nuclear power while New Zealand was anti-nuclear. New Zealand’s prime minister David Lange banned nuclear-powered and nuclear-armed ships from docking in New Zealand ports and even entering New Zealand waters.
The United States refused to confirm or deny whether their ships contained nuclear weapons so this essentially banned all their ships from New Zealand waters. In response, the US suspended it's treaty obligations to New Zealand until they would allow US Naval ships to enter their waters. The US described New Zealand as “a friend, but not an ally.”