Though the four islands located to the northeast of Hokkaido used to be a part of Japanese territory, since the end of World War II, Russia has occupied them. Russia has refused to return them, claiming that they are the spoils of war. At that time, there was an agreement between the Soviet Union (present-day Russia) and Japan that they would not wage war over the lands. Furthermore, Japanese people are aware that Russia broke this treaty by invading those islands after Japan had accepted defeat. At the moment Japan and Russia have been negotiating to solve this territorial issue and conclude their peace pact.