The GCSB not only spies on the Solomon Islands using its Waihopai satellite interception base - it also had a secret listening post inside the country, according to documents provided by the United States National Security Agency whistleblower Edward Snowden.
The GCSB's post in Honiara is equipped with eavesdropping equipment to monitor local mobile phone calls, according to a co-operative reporting effort between the Herald and US news site The Intercept.
The listening post, the GCSB report suggests, was codenamed Caprica. The spying was conducted by a series of GCSB officers based in New Zealand's Honiara high commission building, a source familiar with the operation told the Herald.
The "Caprica collection" sounds like an NSA programme called Stateroom, which uses high-tech NSA and British equipment installed in embassy buildings to spy on local communications. Other Snowden documents have referred to GCSB participation in Stateroom.
In Honiara, the Caprica eavesdropping was under way by 2006 and appears to have continued until 2013. The official with knowledge of the operation told the Herald that the monitoring was in response to the civil crisis in the Solomons at that time, and also the intelligence agencies were very interested in a "battle for hearts and minds" occurring between China and Taiwan.
The Solomon Islands was, at that time, aligned with Taiwan, he said. The 2009 GCSB report - analysed by the Herald and The Intercept - came from the Snowden trove of documents. It shows the monitoring was a joint project with Australian intelligence agencies.
"The result of this collaboration has been the fine tuning of Caprica collection to take advantage of as many of the new [Telekom cellphone site] 1800MHz antennas as possible."
The report said an Australian DSD "requirement" had led to "dedicated" monitoring gear being deployed at the New Zealand Caprica site for the Australian intelligence agency.
Visit tinyurl.com/nzhsnowdenfiles to read the earlier stories in this series.