The Kuril Islands dispute, known in Japan as the Northern Territories dispute, is a territorial dispute between Japan and the Russian Federation over the ownership of the four southernmost Kuril Islands. The Kuril Islands are a chain of islands that stretch between the Japanese island of Hokkaido at their southern end and the Russian Kamchatka Peninsula at their northern end. The islands separate the Sea of Okhotsk from the Pacific Ocean. The four disputed islands, like other islands in the Kuril chain that are not in dispute, were annexed by the Soviet Union following the Kuril Islands landing operation at the end of World War II. The disputed islands are under Russian administration as the South Kuril District of the Sakhalin Oblast (Сахалинская область, "Sakhalinskaya oblast"). They are claimed by Japan, which refers to them as its Northern Territories or Southern Chishima, and considers them part of the Nemuro Subprefecture of Hokkaido Prefecture.