YANJI, China — After the North Korean coal mine where she worked stopped paying salaries, Park Kyung Ok tried her hand at business.

Buttons and zippers, candy and dried squid, fabric, plastic tarpaulins, men’s suits and cigarettes.

“I sold just about everything,” said Park, 44.

But it wasn’t until she started hawking methamphetamine in 2007, she said, that she was able to earn a living.

Methamphetamine, known as orum, or “ice,” is a rare commodity manufactured and sold in North Korea, where most factories sit idle, the equipment rusted or looted. The North Korean government once produced the drug, and others that are illicit in the West. Resourceful entrepreneurs have since set up their own small facilities, and evidence suggests that they are distributing the drug beyond the nation’s borders.

Last month, five alleged drug smugglers — Chinese, British and Thai men among them — appeared in federal court in New York…