New Zealand will push for total ban on nuclear weapons - Jacinda Ardern

Prime Minister Jacinda Ardern said there is an "outlier" amongst countries that have nuclear weapons because Russia now appears to believe that a nuclear war can be won and fought, as she continued to push for the abolition of nuclear weapons.

Speaking to media after her address to the United Nations General Assembly, Ardern said New Zealand never believed the doctrine of Mutual Assured Destruction (MAD), which meant that countries would not start a nuclear war, because they believed they would be annihilated by their enemy in retaliation.

"New Zealand - no one wants to be proven right on this issue," Ardern said.

"We've always had the view that so long as everyone holds them [nuclear weapons] that no one will push the button - New Zealand has never had the view that that is a good strategy or a safe strategy."

Earlier in the day, she told the United Nations that one country - a reference to Russia - believed it could fight and win a nuclear war.

"It takes one country to believe that their cause is nobler, their might stronger, their people more willing to be sacrificed," Ardern said.

"None of us can stand on this platform and turn a blind eye to the fact that there are already leaders amongst us who believe this," she said.

Russia's apparent belief that it could start and win a nuclear war is a reversal from its position in January, when it made a pledge with other nuclear powers who were signatories to the Nuclear Non-Proliferation Treaty that "a nuclear war cannot be won and must never be fought".

American and Russian leaders have been making some version of this statement since leaders Ronald Reagan and Mikhail Gorbachev first said it in 1985.

If the doctrine of MAD is gone, then the world could be closer to a nuclear war than ever before.

Ardern said Russia was an "outlier" and other countries had a far more stable nuclear policy.

"I wouldn't take Russia's position as indicative of the rest of the world."

Ardern recommitted to New Zealand's longstanding position of wanting a total prohibition on nuclear weapons.

"The alternative to removing weapons from the world's nuclear arsenal is we assume the world is safer through the idea of Mutually Assured Destruction - the idea that it is enough of a deterrent to know your neighbour has them as well," Ardern said.

"I don't think anyone feels safer."

Ardern said New Zealand had a good reputation for "standing firm on issues like nuclear non-proliferation and for me it was really important to restate on behalf of New Zealand that ongoing opposition".

She said New Zealand had pushed for a number of nuclear goals, both non-proliferation and disarmament, and the country could be a "principled" voice on disarmament.

"New Zealand is in demand, we're also really highly regarded and that's not just recent times, over decades New Zealand has built a reputation of being strongly consistent and principled," Ardern said.

"I've been lucky enough to witness the reputation that New Zealand has globally on issues that matter like nuclear issues, so I do think actually that it doesn't matter what our size is, the fact we've been so principled and consistent, and that right now the world does need solutions on this question because everyone is feeling vulnerable."