TAIPEI, TAIWAN – Espionage between Taiwan and China has grown more sophisticated because of fewer people-to-people exchanges and more use of internet technology, as relations between the two countries remain chilled Taipei analysts say. China claims sovereignty over Taiwan and insists that the two sides eventually unify, by force if needed. Taiwan President Tsai Ing-wen, bolstered by domestic opinion polls, rejects unification and relations have soured since she took office in 2016. Analysts say those conditions make each side want to know more. Attention has riveted on spying over the past week as Taipei prosecutors evaluate whether former Deputy Defense...