A team of South Korean spies and American private investigators quietly gathered at the South Korean intelligence service in January, just days after North Korea fired three ballistic missiles into the sea. On March 15, the Justice Department and European law enforcement agencies announced the shutdown of a mixing service known as ChipMixer, which the North Koreans allegedly used to launder an unspecified amount of the roughly $700 million stolen by hackers in three different crypto heists — including the $100 million robbery of Harmony, the California cryptocurrency firm. With an international effort to sanction rogue cryptocurrency exchanges and seize stolen money, Carlsen worries that North Korea could turn to less conspicuous forms of fraud