Sakhalin Island is far from the Soviet Union. Why did the Soviet Union capture Sakhalin Island in 1945?

Sakhalin Island is located in the northeast of Eurasia, not far from the Soviet Union. After all, the Soviet Union has been close to Sakhalin Island since it occupied Manchuria outside China. Historically, after Russia invaded Sakhalin Island in China by treaty, it has been competing with the Japanese to acquire Sakhalin Island through exchange. However, after the Russo-Japanese War, Sakhalin Island split in two and the south became Japanese territory. In the late World War II, the Soviet Union sent troops to the northeast and captured Sakhalin Island again. Sakhalin Island has been a Russian territory until now. The main reason why the Soviet Union captured Sakhalin Island in 1945 was to occupy Sakhalin Island. The Soviet Union did this for two reasons. First, Sakhalin Island is a long-term goal of Russians. Second, Yalta Sakhalin Island belongs to the Soviet Union, and the occupation is a matter of course.

First, Sakhalin Island is a long-term goal of Russians.

Since its modern expansion, Russia has occupied a large number of territories, including China1500,000 square kilometers, including Sakhalin Island. After all, Sakhalin Island covers an area of about 76400km? . It is impossible to give up such a large area. China is also the largest island, so Russians will naturally not give up. This is the goal of the Russians for many years. The point is that the Russians occupied Sakhalin Island by treaty. Although it competed with Japan for many years, it completely occupied Sakhalin Island through exchange. However, in the Russo-Japanese War, Sakhalin Island was split in two due to the defeat of the Russians, which was imposed by the Japanese in the eyes of the Russians. Stalin continued this idea, and the occupation of Sakhalin Island was an established strategy. At the same time, Sakhalin Island also has great strategic value. If occupied by the Japanese army, it can directly threaten the Soviet Far East. On the contrary, if you occupy Sakhalin Island, you can push Japan.

The second Yalta stipulated that Sakhalin Island belonged to the Soviet Union.

In the late World War II, the United States compromised with the Soviet Union in order to win over the Soviet Union to participate in the Far East war against Japan. This is the Yalta agreement. At the Yalta Conference, the Soviet Union opened the door to convenience, so there was the Yalta Agreement. On the Far East issue, one of the rewards of the Soviet Union's war against Japan was the return of southern Sakhalin Island and its adjacent islands to the Soviet Union. Therefore, in the eyes of the Soviets, it is natural to occupy Sakhalin Island. Why not?