Russia has denied entry to disputed islands to a mayor from Hokkaido in retaliation for sanctions imposed by Japan over the Ukraine crisis, diplomatic sources said Saturday.Nemuro Mayor Shunsuke Hasegawa was disallowed to join a five-day study tour through July 1 to assess the potential for joint economic activities on the islands off the northernmost prefecture that are controlled by Moscow but claimed by Tokyo, the sources said.The Russian government introduced the retaliatory measure in August 2014, but the number of Japanese people subject to it and their names were not released at that…READ FULL ARTICLE