New Zealand is being labelled "a joke" on defence in the aftermath of its exclusion from the new AUKUS pact.

The defence pact between Australia, the US and the UK will formalise cooperation in the Indo-Pacific, and is seen as a counterweight to China's growing power in the region. Under the deal, the countries will share advanced technologies, including supplying nuclear-powered, but conventionally armed, submarines for the Royal Australian Navy.

Prime Minister Jacinda Ardern reacted by saying the Australian submarines couldn't enter New Zealand's waters, in line with our long-standing anti-nuclear policy.

Now Australia's Sky News host Chris Kenny has gone on the attack, accusing New Zealand of sitting back and letting our allies do the work.

"Not very neighbourly is it," he said on Friday night. "Just exposes what a joke our cousins are across the ditch when it comes to defence and security.

"I think they just want to hide over there and hope that no one turns up. But I'll tell you what - if China turned up then Australia and the US couldn't help out because our vessels would be banned from their waters. It's really that silly. It's strategic laziness, bludging on your mates."

Kenny then played a video mocking New Zealand's '100 percent pure' ads, with captions showing us having '0 percent airforce', '0 percent navy' and '0 percent infantry'.

The video was then cut with footage of New Zealand being invaded by armed forces while military aircraft scream through the sky.

"100 percent there for the taking," the captions finished. "100 percent too easy. 100 percent ours."

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Ardern has said while New Zealand wasn't approached to be part of AUKUS, the pact "in no way changes our security and intelligence ties with these three countries".

"New Zealand is first and foremost a nation of the Pacific and we view foreign policy developments through the lens of what is in the best interest of the region," Ardern said.

"We welcome the increased engagement of the UK and US in the region and reiterate our collective objective needs to be the delivery of peace and stability and the preservation of the international rules-based system."

However National's leader Judith Collins said our absence from the partnership "is concerning".

"It's disappointing that after many years of New Zealand's co-operation with our traditional allies, the current Government appears to have been unable to participate in discussions for 'AUKUS'. It raises serious concerns about the interoperability of New Zealand's defence force systems with our traditional allies in the future."

Citing comments from a senior Pentagon official, The Australian newspaper described the pact as a "'new ANZUS' that sidelines New Zealand". 

But Geoffrey Miller, an international analyst with Victoria University's Democracy Project, told Newshub earlier this week if the other Five Eyes member, Canada, had been part of the AUKUS, then it may have suggested New Zealand was on the outer. But that's not the case.

"Canada and New Zealand both share similarities and positioning regarding China, which is more balanced than those other three. So it's perhaps not a surprise, and that maybe softens the blow somewhat. The fact that it's both Canada and New Zealand not being included."

He said AUKUS appeared to be three close allies formalising their alliance. 

"I think most New Zealanders would probably say good luck to them, but it's not really where we are at these days."