New Zealand military support for the US in the event of an attack by North Korea will be considered "on its merits", the prime minister said today.
Bill English says any military support at this stage is hypothetical and he's still focused on a "peaceful resolution" of nuclear threats between the two nations.
Australia is obliged to back the US in the event of an attack on the US by North Korea, like that threatened by North Korean leader Kim Jong Un on the Pacific US territory of Guam, through the ANZUS treaty.
Australian Prime Minister Malcolm Turnbull says Australia will invoke the treaty if an attack happens.
"In terms of defence, we are joined at the hip," Mr Turnbull told Australia's 3AW radio today.
While New Zealand is a party to the three-way treaty the nation has not been linked directly to the US since the 1980s because of the dispute over US nuclear-armed and nuclear-powered ships.
Mr English said New Zealand would consider any contribution to a US-North Korean war "on its merits".
"While there's been an escalation of rhetoric there isn't any indication that military action's going to occur," he said.
"We're in close contact with the US and Australia but any decision New Zealand makes about North Korea we make according to our own interests."
US President Donald Trump this week threatened North Korea with "fire and fury", which was derided as a "load of nonsense" by North Korea's military.
He upped the ante later in the week, telling reporters the fire and fury comment maybe "wasn't tough enough".
Mr English said he didn't want to see comments that escalate the tension, again describing Mr Trump's latest remarks as "not helpful".
"The US does remain committed to working to resolve these issues without military intervention," he said.
He remains focused on peaceful resolution, working with the UN, US, China and Russia to put pressure on North Korea.