South Korean customs authorities have discovered that illegal foreign exchange transactions involving cryptocurrencies have surpassed 10 trillion won over the past five years. According to NS3.AI, Tether has been widely used in these activities. The value of these uncovered transactions increased significantly from 823.8 billion won in 2021 to 4.7566 trillion won in 2022. Additionally, the number of cases rose from 10 in 2021 to 16 in 2025.