BEIJING (Reuters) -China and Nauru re-established diplomatic ties on Wednesday, after the tiny Pacific island nation unexpectedly severed relations with its now former ally Taiwan in a move the United States described as "unfortunate". The Pacific 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. During a ceremony in Beijing, China's Foreign Minister Wang Yi and his Nauru counterpart Lionel Aingimea formally signed a document to restore bilateral relations, with ties at the ambassadorial level resuming with immediate effect.