New Zealand Defence Force officials warned in April that the country would be shut out of future Five Eyes information sharing if it did not help build a new US-led military data system called Project Arcadia, according to briefings released to RNZ and reported on 9 October.
The papers set out the case Defence officials made as they weighed whether New Zealand should sign up. Joining, they said, would let the Defence Force go “far beyond” what it could afford alone, “without loss of national control”. But the briefings also spelled out what was at stake if New Zealand stayed out.
“Arcadia capabilities will become foundational to the way that we plan, integrate and execute operations with FVEY partners,” the briefings said, using the military shorthand for the Five Eyes group of the United States, Canada, the United Kingdom, Australia and New Zealand. “If NZDF does not commit … it will not have access to these foundational capabilities, becoming effectively cut off from future FVEY information exchanges.”
Another line was blunter still. “Without joining the MOU, NZ risks becoming a lower trust, lower influence partner.”
The MOU is the memorandum of understanding meant to set out long-term oversight and funding for the project. RNZ reported it appears to have been signed in May 2026, about a month after the warning, and said it had asked the Defence Force to confirm the details.
Project Arcadia is a shared digital backbone linking the five countries’ militaries. The United States announced the build in May after a Combined Digital Leadership Summit in Washington, and the US Department of War said at the time that Arcadia “has galvanized this remarkable unity” among the Five Eyes partners, RNZ reported.
When New Zealand’s involvement first became public in June, RNZ reported that the Pentagon saw Arcadia as a way to bring its closest partners up to the attack speeds seen in the Iran war, with artificial intelligence used to process vast amounts of battlefield data into a common picture. At that time Defence Minister Chris Penk’s office said Cabinet approval for funding would be sought as part of the Defence Force’s digital modernisation work, and that the project was in an information-gathering stage.
The newly released papers show the money question is still open. By April the Defence Force had spent about $3 million on Arcadia, and one briefing said it would need to ask for extra funding in Budget 2027 for a build expected to take six years.
“The spread of costs are not known at this point,” an April document said, adding that a US programme office was working on that. The same document argued the project was good value. “NZ’s contribution, relative to the total investment, allows us to receive access to capabilities far beyond what we could afford alone.”
The briefings also claimed a New Zealand hand in the idea itself. According to the papers, New Zealand helped come up with the concept of Arcadia while it led a key Five Eyes information group in 2024 and 2025, and joining would give the country influence over how the military technology develops.
Brigadier E J Harrop, commander of the Defence Force’s Information Command, put it plainly in April when writing to the Vice Chief of the Defence Force. “NZ must ensure we have the skills and modernised systems to fully leverage Arcadia.”
Arcadia sits inside a much larger spending programme. A big lift in the Defence Force’s technology, including data and weapons systems, is central to the $12 billion Defence Capability Plan covering 2025 to 2029. The briefings said Arcadia fits with the Government’s wider Digital Public Infrastructure programme but would remain independent of it, setting up its own platforms “within guardrails, in cost-effective, efficient and secure ways”.
It also builds on a run of US-led projects the Defence Force has joined since 2020, covering everything from the US Navy to the US Space Force. RNZ has previously reported the Defence Force joining the US Army to test high-tech weapons.
The question of sovereignty has followed Arcadia from the start. When it was first reported, Penk’s office said “As with previous Five Eyes arrangements, each nation’s sovereign requirements are maintained”, and the Defence Force said the system was designed so partner nations could better protect their data and have more control over what they share. US defence media reported the design builds a shared data layer on top of each country’s own systems, a choice several nations asked for.
Even so, the new papers frame the decision less as a free choice and more as the price of staying inside the alliance’s information loop. That framing matters because, as RNZ noted, defence spending is large and growing fast but has not become an election issue, even though Budget 2027, which will carry the next Arcadia funding request, will be written by whichever government is formed after the election.
For voters, that leaves open questions that have not yet been tested in public debate. How much will New Zealand ultimately pay into a six-year build whose costs are still being worked out? How much say will a small partner really have over a system largely driven by Washington’s priorities? And is staying closely tied to the US military’s data systems the right call for an independent foreign policy? If defence and foreign policy are part of how you are weighing up the parties, you can use our voting tool to see which party best matches your views.
The Defence Force has not yet publicly confirmed the date the memorandum was signed or what Arcadia will cost over its full life.
Should New Zealand have signed up to Project Arcadia, or does the warning about being cut off from Five Eyes show how little room a small country has to say no? Share your view in the comments below.
This article was written by AI, briefed to report the facts, hopefully without some of the bias people bring to the job 🙂
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