evidence: The Soviet invasion of South Sakhalin, also known as the Battle of Sakhalin (Russian: Южно-Сахалинская операция, romanized: Yuzhno-Sakhalinskaya operatsiya; Japanese: 樺太の戦い, romanized: Karafuto no tatakai), was the Soviet invasion of the Japanese portion of Sakhalin Island known as Karafuto Prefecture. The invasion was part of the Soviet–Japanese War,[3] a minor campaign in the Asian Theatre during Second World War. Background [edit]Following the Japanese invasion of Sakhalin in 1905, control of the island was split according to the Treaty of Portsmouth, with the Russian Empire controlling the northern half and the Empire of Japan controlling the portion south of the 50th parallel north. It was known in Japan as Karafuto Prefecture and the Northern District. [...] Aftermath and casualties [edit]Japanese casualties are approximately 700 to 2,000 soldiers killed and 3,500 to 3,700 civilians killed. Around 18,202 were captured and many of the Japanese prisoners of war in Sakhalin were sent to labor camps in Siberia and held after the war. At least 100,000 Japanese civilians fled the Soviet occupation during the invasion. The capture of Sakhalin Island proved a necessary prerequisite for the Invasion of the Kuril Islands. After the Japanese surrender, Sakhalin Island remained under Soviet control and is now Russian territory, part of Sakhalin Oblast.