Manchuria: Khingan–Mukden offensive operation (9 August 1945 – 2 September 1945) (Lesser Khingan-Mukden area); Harbin–Kirin offensive operation (9 August 1945 – 2 September 1945) (Harbin-Jilin area); and Sungari offensive operation (9 August 1945 – 2 September 1945). Though the battle extended beyond the borders traditionally known as Manchuria—that is, the traditional lands of the Manchus—the coordinated and integrated invasions of Japan's northern territories has also been called the Battle of Manchuria. It has also been referred to as the Manchurian strategic offensive operation. Background and buildup The Russo-Japanese War of the early 20th century resulted in a Japanese victory and the Treaty of Portsmouth by which, in conjunction with other later events including the Mukden Incident and Japanese invasion of Manchuria in September 1931, Japan eventually gained control of Korea, Manchuria and South Sakhalin. In the late 1930s there were a number of Soviet-Japanese border incidents, the most significant being the Battle of Lake Khasan (Changkufeng Incident, July–August 1938) and the Battle of Khalkhin Gol (Nomonhan Incident, May–September 1939), which led to the Soviet–Japanese Neutrality Pact of April 1941. The Neutrality Pact freed up forces from the border incidents and enabled the Soviets to concentrate on their war with Germany, and the Japanese to concentrate on their southern expansion into Asia and the Pacific Ocean. With success at Stalingrad, and the eventual defeat of Germany becoming increasingly certain, the Soviet attitude to Japan changed, both publicly, with Stalin making speeches denouncing Japan, and "privately", with the Soviets building up forces and supplies in the Far East. At the Tehran Conference (November 1943), amongst other things, 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: he wanted to avoid a two-front war at almost any cost yet the Soviet leader also wanted to extract gains in the Far East as well as Europe. The only way Stalin could make Far Eastern gains without a two-front war would be for Germany to capitulate before Japan. Due to the Soviet–Japanese Neutrality Pact, the Soviets made it policy to intern Allied aircrews who landed in Soviet territory following operations against Japan, although 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 steadily accelerated. By