The charges relate to allegedly brokering the sale of missiles, missile parts and expertise from North Korea to "other international entities" and attempting to transfer coal from North Korea to non-government buyers in Indonesia and Vietnam. "This case is like nothing we have ever seen on Australian soil," Mr Gaughan said. Over the weekend, Mr Choi was charged with six offences, including two under Australia's Weapons of Mass Destruction (Prevention of Proliferation) Act 1995 – the first time anyone has been charged under that law. The other charges relate to alleged breaches of United Nations and Australian sanctions against the North Korean regime. Mr Gaughan would not say where Mr Choi had been working but said "the evidence suggests there had been contact with high-ranking officials in North Korea". He said he was not a spy, but "an economic agent". He had been under surveillance for several months as part of Operation Byahaut after the AFP was tipped off by an overseas agency earlier this year. Mr Gaughan stressed that there had been no risk to the Australian public and that no weapons or missile componentry had been imported into this country. "This is black market 101," he said. "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," he said. "This was his goal." Prime Minister Malcolm Turnbull was briefed by AFP Commissioner Andrew Colvin on Sunday on the "very, very serious matter". Mr Turnbull warned anyone thinking of assisting the rogue state that "the AFP will find you".

"North Korea is a dangerous, reckless, criminal regime threatening the peace of the region. It supports itself by breaching UN sanctions, not simply by selling commodities like coal and other goods, but also by selling weapons, by selling drugs, by engaging in cyber crime," he said. Experts told Fairfax Media the North Korean regime was consistently desperate for cash and that its embassies had been "shopfronts" in the past for licit and illicit dealings. Australian-based security consultant Neil Fergus said North Korea was running "an illegal network all over the world and they focus very heavily on it. There have been a number of operations detected throughout the east Asian region over a long period of time, where they have placed people to carry out a number of operations in terms of resources, related to fissile material or weaponry, or technology related to their weapons program." He said the idea of a long-term Sydney resident being an alleged economic agent for the regime was "not at all unlikely". Director of the International Security Program at the Lowy Institute, Euan Graham, said "like many things to do with North Korea, there is a surreal comic element to this ... [but] it's not surprising that they have a sleeper network or an active network overseas where Koreans are resident."

Dr Graham, a former adviser to the British government on North Korea, said the regime had sold missile technology in the past, mostly to the Middle East. The willingness of the Pyongyang regime to turn to illicit means of raising funds was highlighted when North Korean cargo ship the Pong Su tried to smuggle 125 kilograms of heroin into Australia in April 2003. The crew was arrested but subsequently deported. The police allege that Mr Choi's discussions included the subject of setting up a "ballistic missile production facility", the supply of missile construction plans and the provision of North Korean technical specialists for training others outside North Korea. The offences allegedly occurred between August and December this year. The man and some other relatives were the subject of ongoing investigations, Mr Gaughan said. Mr Choi is expected to appear in Central Local Court next week. Australia and North Korea have a history of rocky diplomatic relations. Canberra and Pyongyang briefly had embassies in each other's countries in the mid-1970s, but the DPRK (Democratic People's Republic of Korea as North Korea is formally known) withdrew its diplomats in November 1975. There was little direct contact during the 1990s. In May 2000 Australia resumed diplomatic relations through its embassy in Beijing, and North Korea re-opened an embassy in Canberra in May 2002 but closed it again in January 2008.