Wellington, New Zealand — New Zealand Prime Minister David Lange, whose Labour government's antinuclear policies have strained this country's defense alliance with the United States, flies to New York this weekend to launch an international campaign for disarmament.
In his first major overseas trip since his landslide election victory July 14 , Mr. Lange will speak at the United Nations General Assembly Tuesday and is scheduled to have bilateral talks with foreign ministers of all the acknowledged nuclear powers.
His mission has one major aim - to demonstrate to Washington that Labour's antinuclear policy is not directed at America, but is global.
''We are not turning away from our commitment to a good relationship with the United States,'' he told this reporter in a pre-departure interview. ''Our battle is not with America, but against the escalation of nuclear weaponry and the arms race.''
Labour's election victory rang alarm bells in Washington. His party won power on a platform of reviewing the 33-year-old ANZUS defense treaty linking Australia, New Zealand, and the US - and specifically banning visits to New Zealand ports by American Navy nuclear-powered and nuclear-armed ships.
By chance, the annual ANZUS meeting, attended by Secretary of State George Shultz, was held in Wellington, New Zealand's capital, two days after the election.
The new government had not been sworn in and could not attend. The communique, signed by the US, Australia, and the outgoing New Zealand National government, reaffirmed that access by allied ships to member-nation ports was ''essential to the continuing effectiveness of the alliance.''
Mr. Shultz added at a press conference: ''What kind of an alliance would it be if the United States said it wouldn't send out military forces to this area?''
The US agreed then not to send any ships to New Zealand for the rest of the year, pending further talks.
Since then, grass-roots members of the Labour Party have compounded the problem by voting for New Zealand's withdrawal from ANZUS, closure of a US Air Force Antarctic support base at Christchurch, and a host of other anti-American resolutions.
Lange was quick to disown these, pointing out that party votes did not indicate government policy. He added: ''The Labour Party is not anti-American. I'm not anti-American. The government is not anti-American. Our policy is not anti-American.''
Lange, who is also foreign minsiter, will have talks on the issue with Shultz in New York Monday. But he told the Monitor, ''It would be unrealistic to think there will be any breakthrough in the conflict of our positions.''
New Zealand's nonnuclear stance is firm, he said, indicating that an American concession of some kind would be needed to solve the issue. That could not be expected in the lead up to the US presidential election, so the question would be put off until next year.
He said that in the meantime, ''What we have to do is establish in the mind of the US administration that New Zealand is a very stable country.''
''We hope to persuade them that we have a fundamentally basic relationship. It's not just ANZUS that binds together - it was a result of the relationship, not the cause of it.''
''We have to win the confidence of the administration and genuinely strive for an understanding of each other's positions.''
Lange remains adamant that New Zealand's antinuclear stance does not weaken its commitment to ANZUS. This is why he will hold talks with foreign ministers of the rest of the nuclear club - Andrei Gromyko (Soviet Union), Sir Geoffrey Howe (Britain), Claude Cheysson (France), and Wu Xueqian (China).
''It's very important we should be seen to be talking about our position not in terms of a stance against an ally or traditional friend, but in the context of a broader concern to some development in disarmament.''
Lange says he wants to stress the depth of antinuclear feeling in New Zealand society.
''This is not the concern of a minor or weird minority cult or political sect - it's mainstream, and that has to be conveyed.''
He welcomes a recent reported statement by US Ambassador to New Zealand H. Monroe Browne that Washington is prepared to ''review'' ANZUS if New Zealand wants that.
''It indicates that there is not an inflexibility in the US position, which augurs well,'' Lange says.
Aides say he believes it imperative that the US and the Soviet Union get real nuclear disarmament negotiations under way quickly and agree to ''massive'' cuts in weapons. He believes that New Zealand, though a small country (3.2 million people), has a duty to speak out - particularly, and not in spite of, its defense alliance with the US.
While in New York, Lange is expected to name former Labour Prime Minister Sir Wallace Rowling as his new ambassador to Washington. Sir Wallace, prime minister and minister of foreign affairs from 1974 to 1975, has described Labour's antinuclear policy as ''nonnegotiable.''