Soviet–Japanese Neutrality Pact

• 1. Introduction

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  After Stalin signed the Soviet-Japanese Neutrality Pact, he did something almost no one had seen him do. He personally saw off Japan's Foreign Minister, Yosuke Matsuoka, at a train station. Stalin rarely appeared before foreign diplomats at all, let alone in a public farewell like that. For nearly four years afterward, the two countries fought on opposite sides of a global war. Yet they never fired a shot at each other. Then, in 1945, late in the war, the Soviets scrapped the agreement and joined the Allied campaign against Japan. What made two governments bound to rival alliances decide to look away from each other's wars, and what finally broke that arrangement apart?

• 2. Two Wars One Bargain

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  The Fall of France set off a chain of reactions among the Axis powers, and Moscow wanted calm on its own eastern border. Soviet leaders hoped to safeguard the Far East and focus on the European theater of the war instead. Japan, meanwhile, was stuck in what looked like an endless war against China. Its diplomatic relations with the United States were growing steadily worse too. Those pressures pushed Japanese leaders toward an accommodation with the Soviets. It promised to raise Japan's international standing and protect Manchukuo's northern border from a possible Soviet invasion. Neither side yet knew that Hitler had already briefed his own generals about what a Soviet-Japanese deal might mean for Germany's plans.

• 3. Stalin's Calculation

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  Hitler had told his generals that if the European Axis powers attacked the Soviet Union, Japan would be freed to challenge the United States openly. His reasoning was that Moscow would be too consumed fighting Nazi Germany to threaten Manchukuo. That would give Japan the confidence and provisions it needed to go to war with the Americans. Stalin, for his part, put it simply, saying his country's problems 'can be solved in a natural way if the Soviets and the Japanese cooperate.' Signing the treaty also gave him a chance, before the assembled diplomatic corps, to signal Germany that his bargaining position had grown. That signal was aimed at Berlin, but the treaty he had just signed carried very different obligations toward Tokyo.

• 4. The Moscow Signing

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  On the 13th of April 1941, Yosuke Matsuoka and Ambassador Yoshitsugu Tatekawa signed the pact in Moscow on Japan's behalf. Vyacheslav Molotov signed for the Soviet Union. That same day, all three men also signed a separate declaration covering Mongolia and Manchukuo. Under it, the Soviet Union pledged to respect Manchukuo's territorial integrity, and Japan promised the same for Mongolia. The pact itself bound both governments to maintain peaceful, friendly relations and to respect each other's territorial integrity. It also committed each side to neutrality if the other became the target of hostilities from a third power. The ink was barely dry before the pact began reshaping the war raging in China.

• 5. An Uneasy Neutrality

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  Soviet aid to the Nationalist government in China, then fighting Japan in the Second Sino-Japanese War, stopped as soon as the pact took effect. On the 16th of April, the Chinese Communist Party issued a statement calling the agreement 'a great victory for Soviet diplomacy.' The party added that the pact 'was beneficial to liberation throughout China.' Later in 1941, after Germany invaded the Soviet Union, Japan considered tearing up the pact as a fellow signatory of the Tripartite Pact. Japan chose instead to keep the pact intact and expand south into the European colonies of Southeast Asia. Had Germany won the Battle of Stalingrad, Japan might well have invaded Siberia instead. General Tomoyuki Yamashita, already known for his victory at the Battle of Singapore, was sent to Manchuria in July 1942. There, he was tasked with organizing troops for exactly that possible invasion. That invasion never came. Instead, the next turning point arrived in secret, at a conference on the other side of the world.

• 6. A Secret Bargain At Yalta

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  At the Yalta Conference in February 1945, Stalin secretly agreed to enter the war against Japan. In exchange, the Americans and the British recognized certain Soviet territorial claims in Asia. The Soviet offensive was set to begin within three months of the war in Europe ending. Tokyo, still bound to Moscow by the neutrality pact, had no idea that promise existed. Within weeks, Moscow would begin invoking the pact's own fine print to bring the arrangement to an end.

• 7. Denouncing The Pact

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  On the 5th of April 1945, Molotov informed Japan's ambassador that Moscow no longer wished to continue the agreement. He cited Article Three, which allowed either side to denounce the pact one year before its five-year term expired. The wording suggested Moscow wanted the treaty to end right away. Time magazine reported that the Soviet Foreign Commissar's tone hinted at a coming war. The treaty's own text had set it as valid for five years, due to expire on the 13th of April 1946. Without a denunciation, it would have automatically renewed for another five-year term. When Japanese Ambassador Naotake Sato pressed him on the point, Molotov assured him the treaty would stay in force until April 1946. Under the treaty's own terms, though, the denunciation delivered on the 5th of April meant it would not renew when that date came. That refusal to renew would collide, within weeks, with the surrender of Nazi Germany half a world away.

• 8. The Final Campaign

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  On the 8th of May or the 9th, depending on the time zone, Nazi Germany surrendered, ending the war in Europe. That surrender started the secret three-month countdown Stalin had promised at Yalta. On the 9th of August 1945, just after midnight in Manchuria, Soviet forces crossed into the region. The formal declaration of war followed nearly six hours later. A seven-hour time zone gap meant it could still be dated the 8th of August. Japan's ambassador in Moscow received that declaration at 11 p.m. Moscow time. Japanese forces on the Asian mainland were unprepared and were overrun relatively quickly. In the war's last campaign, Soviet forces took Manchukuo, Mengjiang in Inner Mongolia, and northern Korea. The pact they had signed years earlier promised something different: to 'mutually respect the territorial integrity and inviolability of the other Contracting Party.'