An extraordinary database of CIA documents has been made available, revealing the United States' intelligence agency's history of spying on New Zealand.

The database was put online this week and reveals internal Central Intelligence Agency reports which detail the inner workings of New Zealand political parties, briefings on our Prime Ministers and the times we have upset the most powerful nation in the world.

It is a trove of both treasure and trivia, including:

• The CIA's belief former Prime Minister David Lange accidentally backed himself into a corner on the nuclear-free issue, and US concerns the policy could spread throughout the Pacific.

• That Lange told US officials he believed nuclear propulsion was safe.

• The revelation that New Zealand's nuclear free stance - for which we were punished for decades - didn't make any difference to the US from a military perspective.

• A detailed biography of former Prime Minister Sir Robert Muldoon and detailed accounting of his pro-US sympathies, including that Muldoon saw himself as a world leader in financial leadership despite "limited achievements" at home.

• The suggestion former US President Ronald Reagan tell Muldoon he was his favoured candidate to win an election during a White House visit.

• A McCarthy-era report into communism in New Zealand - a concern which was present throughout the documents into the late 1980s.

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