Japan has frozen the assets of 19 North Korean companies on Friday, to step up pressure on Pyongyang to return Japanese citizens that it had allegedly abducted in the 1970s and 1980s, and to halt N. Korea’s nuclear weapons and missile development. North Korean agents reportedly abducted the Japanese citizens to train as spies and to pass off as Japanese, AP reports. The NK companies, which are already the subject of US sanctions, deal in finance, coal and minerals, as well as in transport, including shipping and the transport of North Korean workers overseas. Japan has now frozen the assets of 103 companies and organizations, and of 108 individuals, under either its own sanctions or Security Council resolutions.