By Ben Blanchard TAIPEI (Reuters) -The U.S. official who heads the body that handles unofficial ties with Taiwan on Tuesday decried Nauru’s “unfortunate” decision to break ties with Taipei shortly after an election and warned that Beijing’s promises often go unfulfilled. The Pacific, where tiny Nauru is located, has become a source of intense competition for influence between Washington which has traditionally viewed it as its backyard, and Beijing, which has targeted Taiwanese diplomatic allies there. China claims Taiwan as its own territory with no right to state-to-state ties, a position Ta…