A South Korean research group says Russia exported more oil to North Korea than previously reported. A new report by the Seoul-based Asan Institute for Policy Studies suggests Russia set up a secret trading system to get around United Nations economic sanctions on North Korea. The report centers on the activities of Russia’s Independent Petroleum Company. IPC was targeted by the U.S. Treasury Department in June 2017 for violating restrictions on oil exports to North Korea. IPC was found to have sold large amounts of oil to Russian-linked companies, the report says. Some of the companies were used to cover up the oil exports to North Korea by falsifying information about which countries the supplies were shipped to. The report says one North Korean state company was found to have bought nearly 623,000 tons of Russian oil worth $238 million between 2015 and 2017.