The Soviet–Japanese Neutrality Pact, also known as the Japanese–Soviet Non-aggression Pact, was a neutrality pact between the Soviet Union and Japan signed on April 13, 1941, two years after the conclusion of the Soviet-Japanese Border War. The agreement meant that for most of World War II, the two nations fought against each other's allies but not each other. In 1945, late in the war, the Soviets scrapped the pact and joined the war against Japan.
Background and history
After the Fall of France and the subsequent expansion of the Axis Powers, the Soviet Union wished to mend its diplomatic relations in the Far East in order to safeguard its eastern border and concentrate on the European theatre of war. On the other hand, Japan, bogged down in a seemingly interminable war with China and with diplomatic relations with the United States rapidly deteriorating, sought an accommodation with the Soviet Union that would improve its international standing and secure the northern frontier of Manchukuo against possible Soviet invasion. Stalin was initially unaware of Hitler's briefing to his generals that an attack on the Soviet Union by the European Axis Powers would enable Japan to challenge the United States overtly. This briefing was based on the belief that if such an attack occurred, the Soviet Union would be too preoccupied with fighting Germany, thus making Japan feel less threatened by any possible Soviet invasion of Manchukuo, allowing Japan to have enough provisions and capabilities to start a war with the United States. This treaty would allow both Japan and the Soviet Union to avoid fighting on multiple fronts. Stalin believed that his "problems can be solved in a natural way if the Soviets and the Japanese cooperate". After concluding the nonaggression treaty, Stalin, in an unprecedented gesture, saw Foreign MinisterYosuke Matsuoka off at the train station. This was symbolic of the importance Stalin attached to the treaty; it also provided him with the occasion - in the presence of the entire diplomatic corps - to invite negotiations with Germany while flaunting his increased bargaining power. The treaty was signed in Moscow on April 13, 1941, by Foreign Minister Yosuke Matsuoka and Ambassador Yoshitsugu Tatekawa for Japan and Foreign Minister Vyacheslav Molotov for the Soviet Union. On the same day, the same people also signed a declaration regarding Mongolia and Manchukuo. The Soviet Union pledged to respect the territorial integrity and inviolability of Manchukuo, while Japan did the same for Mongolia. Later in 1941, Japan, as a signatory of the Tripartite Pact, considered denouncing the Soviet–Japanese Neutrality Pact, especially after Germany invaded the Soviet Union, but made the crucial decision to keep it and to expand southwards invading the European colonies in Southeast Asia instead. This had a direct bearing on the Battle of Moscow, where the absence of a Japanese threat enabled the Soviets to move large forces from Siberia and send them to the front lines against the Germans. It is possible that had Stalingrad fallen, Japan would have invaded Siberia. General Tomoyuki Yamashita, known for his achievements in the Battle of Singapore, was sent to Manchuria in July 1942, and he may have been tasked with organizing the troops for the invasion. At the Yalta Conference in February 1945, Stalin agreed to enter the war against Japan in exchange for American and British recognition of certain Soviet territorial claims in Asia. The deadline for this promised action was three months after the end of World War II in Europe. The deal was kept secret. On April 5, 1945, the Soviet Union denounced the pact with Japan, informing the Japanese government that "in accordance with Article Three of the above mentioned pact, which envisaged the right of denunciation one year before the lapse of the five-year period of operation of the pact, the Soviet Government hereby makes known to the Government of Japan its wish to denounce the pact of April 13, 1941." The wording of the denunciation suggested that the Soviet Union wished to see the treaty go out of effect immediately, and Time magazine reported that the Soviet Foreign Commissar's tone indicated that the Soviet Union might go to war with Japan soon. However, the text of the treaty stated that the pact remained in force until one year after declaration of denunciation by one party, that is April 1946. When pressed by the Japanese Ambassador Naotake Sato, Molotov confirmed that the treaty did remain in force until April 1946. On May 8/9, 1945, Nazi Germany surrendered, ending the war in Europe and starting the secret three-month countdown for Soviet commencement of hostilities against Japan. On August 9, 1945, just after midnight Manchurian time, the Soviets invaded Manchuria. The declaration of war against Japan followed nearly six hours later. Because of the time zone difference of 7 hours, the declaration of war could be still dated August 8, 1945, being presented to the Japanese ambassador in Moscow at 11 p.m. Moscow time. In this last campaign of the war, Soviet territorial gains on the continent were Manchukuo, Mengjiang and northern Korea.
