The Defence Minister is being urged to scrap plans to put missiles and bombs on board the new aircraft that will replace the country's old P-3 Orions.
Ron Mark has announced the purchase of four new P-8A Poseidon maritime patrol aircraft from the United States, at a cost of $2.3 billion.
The planes are similar to the commercial Boeing 737, but can be fitted with missiles, torpedos and solar technology specially designed to hunt submarines.
The Green Party's defence spokesperson, Golriz Ghahraman, said it was a continuation of the old war-style obsession with weapons, and had made that opinion clear to Mr Mark.
"They're incredibly expensive because they've got that war-making capability that we feel New Zealand really needs to lead the way in moving away from."
Ms Ghahraman believes the view we need bigger bombs belongs in another century.
The government has never had to call on the Air Force to arm its planes ready for combat, but the Chief of Defence Air Vice Marshall Kevin Short said that doesn't mean they never shoot missiles.
"We do weapon practice, both dropping bombs and torpedos on a regular basis with a P-3. It's just probably not seen by the public, but we do that to keep our military capability going."
There were good reasons for having aircraft that can carry bombs and track submarines, he said.
"We are a military force and what we wanted for the government is a response option," Air Vice Marshall Short said.
"Just the mere threat of being able to carry weapons and do something that is aggressive."
The announcement of the new aircraft came straight off the back of the government's long-term defence strategy which outlined the global and domestic risks and challenges facing New Zealand.
Mr Mark was proud to announce the biggest purchase of defence capability since the Anzac frigates three decades ago.
"This is a government that's not afraid to make hard decisions, particularly those that are inter-generational in their effect and have an impact on capital spending," he said.
"The previous government put off the hard calls on defence procurement for far too long, it would be irresponsible of this government to continue to kick that can down the road."
National's defence spokesperson Mark Mitchell said National had put a lot of work into this and was pleased to see the project advanced.
"It's pleasing to see this government has finally made the right decision."
In response to questions about the massive $2.3b cost, acting Prime Minister Winston Peters said it was not a lot of money given how long the aircraft will be flying for.
"You've got to factor this over 35 years... In fact the equipment we have now was going 50 years ago."
Mr Peters told Morning Report the military capacities of the planes, such as anti-submarine capabilities, were needed.
"We live in a much more highly stressed area of geopolitical competition because we have left, some of us, a vacuum there which others would fill."
He would not "point fingers" on where threats were from. "It doesn't help our relations internationally and it doesn't help our chance of being a very significant influential force in the Pacific."
Mr Peters said over the years the political system had "stopped being scared to spell out the New Zealand voice, our concerns".
He said China had expressed its concern when he was in that country a couple of months ago.
"They just want to know, as they asked me back then, what does this all mean.
"Our job is to assure them what it means in terms of our diplomatic and foreign policy perspectives."
Ms Ghahraman said she didn't understand why the country needed aircraft with missiles and wouldn't give up on trying to change the minister's mind.
"What we actually can change the world on is the work that we do on the environment, on patrols, on search and rescue in the South Pacific.
"I know he's very proud of that work, so hopefully we will just increase the prominence of that work and our investment in that work, rather than any more war-making capability that we don't need."