The legacy of former Prime Minister David Lange as a champion of the anti-nuclear movement is under threat after the release of new CIA files.
The documents show there were efforts by Lange's newly elected Labour Government in 1984 to find a loophole in its anti-nuclear policy big enough to sail a United States warship through.
The plan to get a warship into New Zealand has been linked by those involved at the time with a planned visit by the USS Buchanan in 1985 - which was refused in a move that was global news and set New Zealand on a course to become nuclear-free.
It was meant to happen differently - but the plan to save the NZ and US relationship went to pieces.
A 1985 CIA file stated that Mike Moore - briefly Prime Minister in 1990 - met the US Embassy the year before. He told officials "the United States should 'finesse' the nuclear power issue by asking to send a conventionally powered ship".
He said that it "should 'tell David privately' that no nuclear weapons would be on board the ship requesting access".
PM's department head Gerald Hensley said it was similar to a plan developed by Lange, to which he was a party, as was then-Chief of Defence Air Marshall Sir Ewan Jamieson and the head of Foreign Affairs at the time.
It saw Jamieson sent to Hawaii to choose a ship obviously unable to carry nuclear weapons or sail under nuclear propulsion - the USS Buchanan being the vessel selected by NZ to break the deadlock.
The "solution" overseen by Lange even saw the US Ambassador at the time visit with a draft of the form which would be used to request a visit, said Hensley.
"I thought ... it would all be very straightforward."
The whole plan went to pieces when news of the visit leaked while Lange was away and Geoffrey Palmer, who was Acting Prime Minister, refused the USS Buchanan entry.
Former Labour Party president and MP from 1984 onwards, Jim Anderton, said he and future Prime Minister Helen Clark were asked by Palmer about the request for the USS Buchanan to visit.
Anderton confirmed he told Palmer if the ship arrived then he would be at the wharf protesting along with "half the Labour caucus".
One of the CIA reports show Anderton would have had the numbers at times, showing the US Embassy was keeping careful count on how many MPs backed Anderton and those behind Lange. It is not clear how it was obtaining the information but Anderton confirmed the numbers as accurate.
Former Cabinet minister Richard Prebble said: "Shortly after came the invitation to debate the issue at the Oxford Union and Lange's evolution into a nuclear-free warrior.
"The Cabinet was divided about Lange going to the Oxford Union debate. What he said to us was the ... Union debate was ... on his bucket list of things he would love to do.
"It was actually an indulgence. We were very fond of him and he was a great speaker."
A month later, Lange was on the world stage in England, debating the proposition "nuclear weapons are morally indefensible".
Prebble said the conflicting theories of Lange becoming an anti-nuclear hero by accident or design had only one real outcome.
"I'm afraid evidence of the accidental is overwhelming."
Anderton said Lange's staunchness on the nuclear issue "is accurate if you had one arm ... up his back". "From [outside] he was a great advocate. I always smile a bit about that."