In the 1970s and 1980s, dozens of Japanese citizens were abducted by North Korea. Many were used to help train North Koreans to fit into Japanese society as spies. Officially there were just 17 such cases but Japan's National Police Agency estimates that as many as 860 of the nation's missing persons may have been abducted by Pyongyang. Now Tokyo says it is determined to secure the return of all of its citizens.