According to this article in Time (via), it’s not forged banknotes, or drugs, or missiles, that are making the serious money for the North Koreans – it’s counterfeit cigarettes:
A confidential report compiled by investigators working for a coalition of major U.S., European and Japanese tobacco companies indicates that North Korea has developed a highly lucrative source of hard currency: counterfeit cigarettes. The 11-page document, a copy of which was obtained by TIME, outlines in unprecedented detail the inner workings of this illicit business and the extent to which it may have led North Korea’s rogue regime to ally itself with crime syndicates from mainland China and Taiwan.
Based on information from undercover agents, informants and industry insiders, the report, which is dated June 29, 2005, offers a unique glimpse of the scale and sophistication of North Korea’s illicit-cigarette industry, which has allegedly counterfeited a vast array of brands—from Marlboro to Davidoff. The report estimates that production from 10 to 12 North Korean factories in the counterfeiting business may total 41 billion cigarettes a year, generating annual revenues of $520 million to $720 million. It’s not clear how much of this money flows to the regime of dictator Kim Jong Il, whether in duties or payments “for protection,” but the report speculates that its share of the profits may amount to $80 million to $160 million a year. That would be quite a windfall at a time when the North’s economy is reeling and the U.S. is trying to pressure Kim to abandon his nuclear-weapons program by cracking down on his regime’s income from business exploits as diverse as trafficking drugs and counterfeiting $100 bills.