This is about the most factual and objective summary that I can find on the 'Net to the background of that "anti-nuclear" legislation.
"Close defence cooperation with the United States and Australia during the second world war lead to the ANZUS defence pact between the three countries. However, concern about French nuclear testing in the pacific at Mururoa Atoll, and about the presence of nuclear warheads or reactors on US ships visiting New Zealand, contributed to growing antinuclear sentiment in New Zealand. Under the Labour Party government of David Lange, this lead to the passage in New Zealand of antinuclear legislation, preventing visits by ships carrying nuclear weapons or powered by nuclear reactors. In theory, warships that did not fall into this category were not blocked. However, New Zealand insisted on direct confirmation that a ship was not nuclear-armed or nuclear-powered, something which clashed with the United States' security policy of "neither confirming nor denying" nuclear capability on specific ships. Because the United States would not reveal a ship's nuclear status, New Zealand could not determine whether the ship met New Zealand's legal requirements, and so would not grant permission for a visit. This effectively ended visits by United States ships to New Zealand. The US took the position that this legislation effectively prevented practical alliance cooperation. New Zealand, in contrast, claimed that the removal of nuclear weapons from the Pacific was actually beneficial to the alliance's goal of regional security.
After increasingly acrimonious debates, the United States formally suspended its ANZUS security obligations to New Zealand in August 1986. This suspension remains in effect today, although the US no longer carries nuclear weapons aboard its surface naval vessels. In recent years, there has been some debate in New Zealand about removing the antinuclear legislation, with the ACT New Zealand party commenting in favour of doing so and the National Party "considering" it. However, public opinion remains strongly in favour of the ban. "
(Just as a word of explanation here about ACT. The founders of this right wing party were members of the fifth Labour Government (which was left wing), and under David Lange as PM, responsible for the anti-nuclear legislation.)
But there is just a little more to the start of the story.
For me, NZ's anti-nuclear stance has its genesis in the 1950's and early 60's. At that time Britain was testing at Christmas Island, the US was testing further north. I have strong recollections of the continuing reports of scientists testing Strontium 90 levels in both pasture and milk over a period of some 10 to 15 years. The conclusion was that there was clear connection between Sr90 and atmospheric testing. Those soil tests were resumed when the French moved their test programmes from the Sahara to Mururoa.
Why was this so important? Because our major markets had expressed concern and threatened to stop buying dairy product because of the potential Sr90 contamination. What started as a protective (it is not as bad as you think) study, became an early weapon against the atmospheric testing of nuclear weapons. It formed a strong part of the case that NZ took to the World Court in the 1980's against atmospheric testing of nuclear weapons.
When the US started sending nuclear powered and armed ships under the "requirements" of the ANZUS Treaty, it soon became apparent to the ordinary kiwi that the US must have a very small navy of just a few nuclear powered ships. Well, I mean, they were the only ones that ever arrived here. Conventional powered ships from the US Navy NEVER visited a NZ port after 1970.
The "requirement" to accept US Naval visits was justified by a clause of the Treaty setting out the need for "exchange of personnel, joint training, and exercises." The strange thing was, that these ships always arrived (with respectful notice) out of the blue yonder, and left some while later as silently and as rapidly as they came. Exercises? Joint training? We used our P3's to track them until they left our territorial waters...then politely let them go on their way.
Another aspect not satisfactorily covered in the quote above is the fundamental and extreme distrust of nuclear weaponry by the ordinary Nzer. The insanity of the MAD policies (and how apt the name is) of the Cold War was always beyond comprehension.
The third piece of the jigsaw that has not fitted properly in the quotation above is the consequences of NZ protest against French testing at Mururoa.
Understand here that one of the primary clauses of the Treaty stated that an attack on any one of the members would be considered an attack on all.
The French (government) terrorist attack in 1984 that resulted in the sinking of Rainbow Warrior in Auckland Harbour brought a few sniffs and some very firmly turned backs. There was no support from either of the other ANZUS members to NZ's protests. There might have been a quiet "That was a F***** stupid thing to do" in Chirac's ear, but nothing was said in public.
Given that experience, the third piece was the attitude "If NZ gets chucked out of ANZUS, what have we lost?"
Personally, and I think that a majority of Nzers would agree, the anti-nuclear legislation was the best thing that we could have done. It has given NZ a continuing, free and independent voice in international affairs. It has allowed this country to determine for itself when and at what level we involve ourselves in international disputes.
Quite frankly, I believe that this is what has gotten up the collective nose of the US more than anything. The absolute cheek and inexpressable gall of a bunch of uneducated, no-hoper, rugby playing, island farmers to give the US the bird and say "We stand here".
The most outstanding thing, the one thing that ties all of this back to comments about NZ - US relations, is the one that is never mentioned.
When the US expelled NZ from ANZUS they also down-graded their own assessment of NZ's diplomatic standing from "Most Favoured Nation" status to "good friend" (the capital letters are important). That, if I am understanding this correctly, puts us on the same level as Algeria and Yemen, one level above "evil", and two levels below Russia, China, Ukraine, and Saudi Arabia, all of whom hold MFN status.
It was this last point that I was going to tie back to the question of "how to fight terrorism", and the futility of isolationism. I will think on that a little longer...
Finally, any political party that suggests the weakening or the removal of this legislation is committing political suicide. That was learned by Donny Brash in very short order. To his credit he backed off, helped no doubt by the strong arms of some of the older members of his party.
ACT, as I suggested earlier, is like a toothpaste looking for market distinction. Good luck to them. Rodney should go hide...