the Soviets building up forces and supplies in the Far East. At the Tehran Conference (November 1943), Stalin, Winston Churchill, and Franklin Roosevelt agreed that the Soviet Union would enter the war against Japan once Germany was defeated. Stalin faced a dilemma since he wanted to avoid a two-front war at almost any cost but also wanted to extract gains in the Far East as well as Europe. The only way that Stalin could make Far Eastern gains without a two-front war would be for Germany to surrender before Japan. The Soviet–Japanese Neutrality Pact caused the Soviets to make it policy to intern Allied aircrews who landed in Soviet territory after operations against Japan, but airmen held in the Soviet Union under such circumstances were usually allowed to "escape" after some period of time. Nevertheless, even before the defeat of Germany, the Soviet buildup in the Far East had steadily accelerated. By early 1945, it had become apparent to the Japanese that the Soviets were preparing to invade Manchuria, but they were unlikely to attack prior to Germany's defeat. In addition to their problems in the Pacific, the Japanese realised that they needed to determine when and where a Soviet invasion would occur. At the Yalta Conference (February 1945), Stalin secured from Roosevelt the promise of Stalin's Far Eastern territorial desires in return for agreeing to enter the Pacific War within two or three months of the defeat of Germany. By mid-March 1945, things were not going well in the Pacific for the Japanese, who withdrew their elite troops from Manchuria to support actions in the Pacific. Meanwhile, the Soviets continued their Far Eastern buildup. The Soviets had decided that they did not wish to renew the Neutrality Pact. The Neutrality Pact required that twelve months before its expiry, the Soviets must advise the Japanese and so on 5 April 1945, they informed the Japanese that they did not wish to renew the treaty. That caused the Japanese considerable concern, but the Soviets went to great efforts to assure the Japanese that the treaty would still be in force for another twelve months and that the Japanese had nothing to worry about. On 9 May 1945 (Moscow Time), Germany surrendered and so if the Soviets were to honour the Yalta Agreement, they would need to enter war with Japan by 9 August 1945. The situation continued to deteriorate for the