Recently, Japan described four islands whose ownership it disputes with Russia as illegally occupied in the latest version of a diplomatic Bluebook.

The Soviet Union(now Russia), which declared war on Japan days before Emperor Hirohito announced his country’s surrender on Aug. 15, 1945, seized the islands off the northeastern coast of Hokkaido, and expelled all 17,000 Japanese residents and has held the land ever since.

The islands are known as the Northern Territories in Japan and the Southern Kurils in Russia. Japan’s official position is that the islands — home to rich fishing grounds — are an inherent part of its territory and are under illegal occupation. Russia insists that it owns the isles, which have been inhabited by its own citizens for generations.

The disputed islands of Iturup, Kunashir, Shikotan, and Habomai lie at their closest point just a few kilometers off the north coast of Hokkaido, the northernmost of Japan’s main islands. The four disputed islands are located to the southeast of the Russian island of Sakhalin and are administratively part of the same region.