A new book on the global Five Eyes spying alliance posits New Zealand as contributing beyond its status as the most junior of the allied partners.
Its value was such that New Zealand's intelligence links endured through the Anzus rift brought about through the nuclear-free stance adopted in the 1980s, even though military ties were severed.
The Secret History of the Five Eyes delves into the 76-year long intelligence-gathering alliance that placed New Zealand at the espionage table alongside Australia, Canada, the United Kingdom and the United States.
The Five Eyes grouping was founded in a 1946 agreement between the UK and the US which was expanded in 1956 to formally include Australia and New Zealand as partners. Its existence remained secret for more than 50 years. Helen Clark once said during her time as Prime Minister "its existence was actually never openly admitted".
Author Richard Kerbaj said New Zealand's "nimble" intelligence analysis capability and the country's geographical location endorsed its place in a network in which all other countries played second-string to the US.
"The New Zealanders have the ability to move at a very fast pace because there are very few people in the system."
He said the imbalance between intelligence gathering by the US and the other countries in the alliance was clear in a budget comparison. The US spent about NZ$98 billion compared to the UK's $6b and New Zealand's intelligence community budget of $196m.
"America is the lead singer and everybody else is a back-up singer," Kerbaj said.
The US could operate alone across the regions covered by the Five Eyes network but it would miss out on the "diversified thinking" which was a strength, he said. For New Zealand, its ability to be a "dissenting voice" was a particular strength.
Kerbaj's reporting for the book secured scoops involving other nations' intelligence agencies, including the extraordinary tale of the Canadian spy who smuggled a British teenager into Syria at a time when the United Kingdom's intelligence agencies were trying to stop the so-called "jihadi brides".
On New Zealand, he wrote that he had "found the least amount of information relating to the role of New Zealand in the alliance", partly because it was the "smallest contributor".
The book included key anecdotes that placed New Zealand's role in the global intelligence world through the lens of the Five Eyes.
It also showed, as Kerbaj told the Herald, that "if [NZ] didn't carry any value, they wouldn't be brought into the fold and they wouldn't be in the fold".
An interview with Admiral Mike Rogers, a recent director of the United States' electronic surveillance agency, the National Security Agency, used the nuclear-free Anzus rift as an example of how the intelligence alliance survived diplomatic rifts.
Rogers was quoted saying the NSA had fought at the time to preserve New Zealand's position, telling the White House "we get so much value out of this that the price would far exceed the benefit" if the alliance became the "Four Eyes".
It was one event among a string which had placed pressure on the alliance over the years, including Britain refusing to expel Soviet spies during the Cold War and suspicions the CIA plotted to depose left-leaning Australia premier Gough Whitlam.
Beyond the rifts, Kerbaj detailed decades of operations carried out by member countries of the Five Eyes which proved its worth. In it, he described how global spread of the alliance and its collective coverage led to partnerships on specific operations which directly served a few member countries but repeatedly made the case for the alliance.
Examples involving New Zealand included our role supporting British intelligence-gathering for the Falklands War through the new Government Communications Security Bureau. Using a listening station at Waiouru, GCSB staff picked up Argentinian naval traffic and passed it to the UK.
In the 1980s, the GCSB carried out "prolific" targeting of nations including China, East Germany, Egypt, Japan and Vietnam through its new intercept station at Tangimoana on the Manawatū coast north of Wellington.
Kerbaj highlighted how Snowden's leaks in 2013 revealed that the GCSB's expansive approach continued, intercepting satellite data from friendly Pacific countries such as Fiji and Tonga while teaming up with the NSA to hack into the Chinese consulate in Auckland.
The thesis of Kerbaj's book was that the Five Eyes was an unmatched intelligence network with an unmatched capability and reach. And, despite the imbalance between the US and the other partners, it operated in a non-hierarchical way.
UK diplomat and former intelligence chief Sir John Sawers told Kerbaj the annual Five Eyes leadership meetings - such as that recently held in Queenstown - were based on personal engagement at the highest level.
It would see the "heads of the CIA and the FBI and the NSA … with the heads of the services of New Zealand and Canada as well as the heads from the UK and Australia". "That leads to a level of personal engagement at top level which feeds down … to the very close collaboration that was taking place at operational level."
Kerbaj highlighted the agencies' failure to detect the Rainbow Warrior plot in which French saboteurs bombed a Greenpeace ship in Auckland harbour to stop it protesting nuclear testing in the South Pacific.
He floated questions over whether the NSA picked up chatter ahead of the bombing and "withheld it from New Zealand as a repercussion for its anti-nuclear stance".
Retired diplomat and public servant Gerald Hensley chaired the NZ Intelligence Council at the time and said there were "rumours among journalists" but no actual evidence emerged that intelligence was withheld on the Rainbow Warrior.
Hensley's recollection supported Kerbaj's reporting on New Zealand's continued access despite the Anzus rift, saying it was agreed in 1985 "there would be no change in the sharing of signals intelligence".
"Other members of the Five Eyes, especially Britain and Canada, made it clear that they were strongly opposed to any diminution of signals sharing with NZ, because of the undesirable precedent it would set for any future disagreements."
Hensley recalled one US official saying "the British have been all over us" before it was agreed there would be no change.
• The Secret History of the Five Eyes: The Untold Story of the International Spy Network by Richard Kerbaj is out in New Zealand today for $39.99.