Under the pact, Australia will be armed with nuclear-powered submarines in the 2030s, and begin building its own in the 2040s, aiming to curb China's growing influence in the Pacific region.
It is a highly controversial deal for many reasons, notably, the eye-watering cost to Australia, the perceived antagonisation of China, and nuclear proliferation in the region.
Since its 2021 announcement, Aukus collaboration has expanded into a second non-nuclear pillar involving collaboration of "advanced capabilities" such as undersea warfare, cyber technologies and AI.
Earlier in 2024, Aukus countries announced they would collaborate with Japan on pillar two, and in a statement issued early on Wednesday, leaders of the three Aukus nations confirmed advanced talks with three more nations.
"Recognising these countries' close bilateral defense partnerships with each member of Aukus, we are consulting with Canada, New Zealand, and the Republic of Korea to identify possibilities for collaboration on advanced capabilities under Aukus Pillar II," the statement read.
Since taking office in November, Christopher Luxon's conservative coalition government has moved to align New Zealand with the strategic outlook shared by Australians and Americans.
On a trip to Canberra this year, Mr Luxon said he wanted Kiwi defence to be a "force multiplier" to Australia - NZs sole defence ally.
His government has also delayed a defence capabilities review, which will outline key procurement needs for the next decade, to better integrate with Australian forces.
This has concerned many on the left of Kiwi politics, including Ms Clark, who argues it threatens economic ties with China, was undemocratic, and could lead to a formal alliance with Washington.
"The latest Aukus statement by US, UK, Australia on identifying how NZ could collaborate with Pillar 2 is part of stepped up choreography towards NZ signing up (to) a US-led military relationship," she posted on social media.
"There was no pre-election warning from those now in government in NZ of an intention to move NZ back into such relationships."
Unlike Australia, NZ does not have a defence alliance with the United States, having abandoned the ANZUS treaty in the 1980s in a spat over nuclear warships.
Ms Clark believes a shift closer to Washington's orbit marks an end to NZ's carefully crafted foreign policy of recent decades, calibrated to enjoy good relations with both Beijing and Washington.
She noted the US did not offer NZ a security guarantee, as it did Nato allies, or a free trade deal, as it does Australia.
"The current NZ govt continues to signal clearly an end to nearly four decades of NZ's independent foreign policy - in return for economic insecurity & being led along by the strategic objectives of others," she said.
