<Dd> Franco - Thai War </Dd> <Dd> Ecuadorian--Peruvian War </Dd> <P> The Soviet--Japanese War (Russian: Советско - японская война; Japanese: ソ連 対日 参戦, soren tai nichi sansen "Soviet Union entry into war against Japan") was a military conflict within the Second World War beginning soon after midnight on August 9, 1945, with the Soviet invasion of the Japanese puppet state of Manchukuo . The Soviets and Mongolians terminated Japanese control of Manchukuo, Mengjiang (Inner Mongolia), northern Korea, Karafuto, and the Chishima Islands (Kuril Islands). The defeat of Japan's Kwantung Army helped in the Japanese surrender and the termination of World War II . The Soviet entry into the war was a significant factor in the Japanese government's decision to surrender unconditionally, as it made apparent the Soviet Union would no longer be willing to act as a third party in negotiating an end to hostilities on conditional terms . </P> <P> At the Tehran Conference in November 1943, Joseph Stalin agreed that the Soviet Union would enter the war against Japan once Germany was defeated . At the Yalta Conference in February 1945, Stalin agreed to Allied pleas to enter World War II's Pacific Theater within three months of the end of the war in Europe . On July 26, the US, UK and China made the Potsdam Declaration, an ultimatum calling for the Japanese surrender which if ignored would lead to their "prompt and utter destruction". </P>

When did the soviet union entered the pacific war against japan