TAIPEI, Taiwan – Espionage between Taiwan and China has become more sophisticated due to fewer people-to-people exchanges and greater use of Internet technology, as ties between the two countries remain cold, Taipei analysts say. China claims sovereignty over Taiwan and insists that the two sides be ultimately united by force if necessary. Taiwan’s President Tsai Ing-wen, swayed by domestic opinion polls, rejects integration and relations have soured since taking office in 2016. Analysts say these positions make each side want to know more. The espionage has gained attention over the past week as Taipei prosecutors assessed whether former Deputy Defense...