The Republic of Korea regrets that Japan is undermining relationship with us by challenging to deprive Korean sovereignty of Dokdo. Dokdo has been Korean territory more than fifteen hundred years. Korean title to Dokdo is indisputable, borne out by a wide variety of historical and documentary evidences, including documented cases where the Japanese government itself recognized Korean sovereignty of the island. Japanese historical analysis also recognizes Dokdo is truly Korean territory. Take a look this clip ~