Police swooped on Eastwood, a suburb of Sydney on Saturday in a dramatic arrest to prevent a sale allegedly worth “tens of millions of dollars”.
The suspect was arrested for attempting to sell WMD related equipment and warheads, including software for the guidance systems of ballistic missiles.
The charges are the first of their kind to be brought in Australia as tensions between Pyongyang and the rest of the west heat up.
AFP Assistant Commissioner Neil Gaughan told reporters: “This man was a loyal agent of North Korea, who believed he was acting to serve some higher patriotic purpose.”
“This case is like nothing we have ever seen on Australian soil.”
Choi was also allegedly involved in coal sales to Indonesia and Vietnamas North Korea is hit with sanctions which are strangling its economy.
Police described Choi as a “loyal agent” who believed himself to be acting for “some higher patriotic purpose”.
He was born in South Korea but lived in Australia for more than 30 years and was a naturalised citizen, police said.
Working as a hospital cleaner, he lived by himself in a rental unit in the Sydney suburb of Eastwood and was known in the local Korean Christian community.
However his former church friends claim they broke off their friendship with him when he began to express support for North Korea.
He had allegedly “turned”, and visited the rogue regime frequently, with one aquiantance saying: “I hated that my husband met with him and I don’t like anything related to North Korea.
“All those trips to North Korea — he was very private and we thought it was very strange.
Gaughan said the man had been in touch with high-ranking North Korean officials but no missile components ever made it to Australia.
He also said there was no indication officials in Indonesia or Vietnam had been involved in the attempted coal sales.
Gaughan said: ”This is black market 101.”
“We are alleging that all the activity occurred offshore, and was purely another attempt for this man to trade goods and services as a way to raise revenue for the government of North Korea.”
The Sydney man was identified by the Australian Broadcasting Corporation and other media as 59-year-old Chan Han Choi, who they said had been living in Australia for more than 30 years and was of Korean descent.
He was arrested in the on Saturday and was due to face court later on Sunday, police said, after Mr Choi came to the attention of authorities earlier this year.
Cash-strapped North Korea has come under a new round of stricter United Nations sanctions this year after pressing ahead with its missile and nuclear programmes in defiance of international pressure.
Tensions have risen dramatically on the Korean peninsula because of the North’s ballistic missile launches and its sixth and most powerful nuclear test, as well as joint military drills between South Korea and the United States that the North describes as preparation for war.
The Australian Federal Police (AFP) said the man will be in court on Wednesday.