It sounds like a plot straight out of a B movie ― a South Korean drug ring is recruited to make methamphetamine in North Korea and then given spy missions, including assassinations of key North Korean defectors.

According to the authorities who busted the ring after testimony by a former North Korean agent who defected to the South, North Korean agents approached a South Korean drug dealer in China in 1997 with a deal in which the North would provide a place to make methamphetamine if South Koreans provided the necessary equipment, ingredients and technology. The two sides agreed to split the manufactured methamphetamine 50:50.

What happened next is quite incredible. The three South Korean recruits made the necessary purchases in China and South Korea and shipped them to the North through the train service running between Dandong, China, and Sinuiju in North Korea, and cargo ships connecting Busan and Najin ports. In November 1998, the three South Koreans entered North Korea via the Yalu River. Discovering that a key ingredient for manufacturing methamphetamine could not be found in the North, the group returned to Korea and purchased ephedrine hydrochloride and slipped back into North Korea in May 2000, escorted by the North Korean military.

After producing 70 kg of methamphetamine, the group crossed into China, escorted by the North Korean military, and were handed 35 kg of the drug as promised. As to the whereabouts of the drugs, the group insists that they were seized by the Chinese security officials.

The investigators also discovered that from 2004 to 2013, the drug ring was ordered to assassinate Hwang Jang-yup, the highest-ranking North Korean defector, and other prominent anti-North Korea activists, as well as hand over national security-related materials. The group was paid $4 million for their spying activities.

After a few failed attempts at killing Hwang, including one involving a contract killer based abroad, the assassination plan came to an end when Hwang died of natural causes in 2010.

The authorities have suspected for quite some time that North Korea may be involved in drug trafficking but this is the first case it has confirmed of North Korean agents’ involvement in methamphetamine production. The case illustrates that cash-strapped North Korea will not hesitate to engage in criminal activities.

More worrisome, however, is the ease with which the South Korean drug dealers were recruited and how their involvement with North Korea broadened to include spying and assassination. According to North Korean watchers, this is a classic case of how people are trapped into spying for the North: Potential candidates are enticed with a money-making deal and once they take the bait, they are ensnared into spying. Failed small-time South Korean businessmen in China are easy prey, they say.

The authorities say that they are widening the investigation to see if other people may have been involved. Had it not been for the testimony of the North Korean defector, this incident may never have come to light. The case illustrates how we should stay vigilant against North Korean spy activities in the South, including the recruiting of South Koreans.