It is 33 years since the last nuclear vessel came to New Zealand: the nuclear-powered attack submarine USS Queenfish that visited Auckland in 1983 equipped to launch five-kiloton nuclear weapons. It was the last, because soon after New Zealand banned nuclear-armed and powered warship visits.
Now the Government has invited a United States warship to visit the country as part of this year's Navy 75th anniversary celebration. Could that spell the end of the nuclear free policy? There has been worried discussion on this question.
The answer - based on reliable, publicly available sources - is no, not at all. If the US Navy sends a warship in November, it will be on New Zealand's terms. The nuclear free policy is not threatened.
The last time a US warship was planned to visit New Zealand was in 1985, when the US Government requested port access for an unnamed vessel. David Lange's government had recently been elected on a wave of public anti-nuclear feeling, promising the nuclear free policy. It was a showdown.
If the warship was equipped to carry nuclear weapons - the US Navy always refused to confirm or deny whether nuclear weapons were actually on board - then the few-month-old nuclear free policy would have been finished. A succession of other possibly nuclear-armed vessels would have followed and New Zealand's nuclear free status would have been a sham.
As the showdown approached, supporters of the nuclear free policy distributed a list of all the US warships and submarines that were equipped to carry and launch nuclear weapons. If the visiting US ship was on the list, it had to be refused. If it wasn't on the list, it could visit under the new policy.
The warship turned out to be the USS Buchanan, a guided missile destroyer equipped to carry 10-megaton nuclear weapons. The Lange government refused to let it visit. The nuclear free policy was under way.
Back then there had been a long list of US nuclear-capable vessels. The US Navy had over 3700 naval nuclear weapons for use on about 240 warships and submarines.
The nuclear weapon systems on the warships and submarines were 1950s and 60s creations of the nuclear arms race. One-kiloton Terrier nuclear missiles were for firing at aircraft. The Queenfish and Buchanan were equipped to fire nuclear depth charges, designed to detonate underwater and destroy Soviet submarines. Other nuclear bombs of up to hundreds of kilotons were made to drop from planes flying from aircraft carriers and as warheads on Tomahawk cruise missiles flying into enemy cities.
A lot has changed between then and now. These Cold War-era nuclear weapons were getting old in 1985 and have gradually been removed from the vessels since then.
The first ones to be retired and destroyed were the nuclear depth charges (submarine versions in 1989, warship versions in 1990). They had minimal military value and had created diplomatic conflict around the world when countries like New Zealand objected to nuclear weapons on visiting vessels.
The Terrier nuclear missiles were also retired in 1990.
Next, in the early 90s, the US Navy withdrew the aircraft carrier-based nuclear weapons. By 1994 the entire surface fleet was denuclearised, leaving only Tomahawk cruise missiles on attack submarines.
The nuclear-armed cruise missiles lasted longest. They were still being test-launched in 2005. But they were becoming obsolete. Finally, in 2012, a US military document noted that "All W80-0 [Tomahawk] warheads in the stockpile have been dismantled".
In 1985 there were 3700 nuclear weapons for 240 nuclear-capable warships and attack submarines. Today both numbers are zero. If there's a US warship at the navy's 75th anniversary event it won't be equipped for nor carrying nuclear weapons. Nor will it be nuclear powered (it's well known which vessels have nuclear propulsion and the law is clear). A visit would not clash with the nuclear free policy.
The US Navy could have accepted the New Zealand policy in the first place and sent one of its non-nuclear vessels to New Zealand in 1985. Or later, as the naval nuclear weapons were progressively retired, it could easily have sent warships to New Zealand that were consistent with the nuclear free policy. But the US Navy does not like restrictions on where it can go and it has refused to visit New Zealand under the nuclear-free policy. This attitude has continued for over 30 years.
Of course many people may prefer not to have a US warship visit even without nuclear weapons. Since the Cold War these warships have mainly been used in Middle East wars, which left 100,000 dead, millions displaced and the world a less safe place.
Nonetheless, the historic significance of a US naval visit this year would primarily be that New Zealand's nuclear free policy had prevailed. Despite 30 years of more and less subtle pressure, the policy is still there. In deciding to visit, it would be the US Navy, not New Zealand, that had changed its position. The many thousands of people who actively campaigned for the nuclear free policy - writing, marching, sailing in boats and all - and the many more who supported them, should celebrate this achievement. Like the suffragettes and generations of nature conservationists, they have helped shape the country we live in. The policy is now deeply embedded in our national identity.
It is also, unfortunately, still badly needed. The world has more than 15,000 nuclear weapons, many ready to launch in minutes. The policy continues to ban all countries' nuclear weapons from New Zealand and prohibits assistance to nuclear weaponry in other parts of the world.
The risk of nuclear conflict in 2016 is the highest it has been since the late Cold War of the mid 1980s. New Zealand's stand against nuclear weapons remains important and potent - and is here to stay.
Nicky Hager is an author and investigative journalist.
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