日露和親条約
The first Russo-Japanese agreement to deal with the status of Sakhalin and the Kuril Islands was the 1855 Treaty of Shimoda, which first established official relations between Russia and Japan. Article 2 of the Treaty of Shimoda, which provided for an agreement on borders, states "Henceforth the borders between Russia and Japan will pass between the islands Iturup (Etorofu) and Urup (Uruppu). The whole island of Iturup belongs to Japan and the whole island Urup and the other Kuril Islands to the north constitute possessions of Russia". The islands of Kunashiri, Shikotan and the Habomai Islands, that all lie to the south of Iturup, are not explicitly mentioned in the treaty and were understood at the time to be a non-disputed part of Japan. The treaty also specified that the island of Sakhalin/Karafuto was not to be partitioned but was to remain under a joint Russo-Japanese condominium.