At the time, Labour Prime Minister David Lange refused to allow the USS Buchanan to enter New Zealand because the Americans refused to confirm or deny whether it was carrying nuclear weapons. In response, the US suspended military ties.
New Zealand and US ties have improved in recent years, and the two militaries have carried out joint exercises. But the US has not sent a warship to these shores.
Foreign Affairs Minister Murray McCully said this evening that the law required the Prime Minister to make a determination "that foreign military aircraft and vessels are not nuclear powered or carrying nuclear weapons before entering New Zealand".
Mr McCully said the same legislation applied to all foreign visiting military aircraft and ships.
American warships no longer carried nuclear warheads. But the US has not previously confirmed or denied whether its ships were nuclear-powered.