the Russian Civil War. It sent 2,300 troops in Siberia and North Russia in 1918 after the request by the Chinese community in the area. Mongolia and Tuva became contested territories. After being occupied by Chinese General Xu Shuzheng in 1919 and then by the Russian White general turned independent warlord, Ungern von Sternberg, in 1920, Soviet troops, with the support of Mongolian guerrillas, led by Damdin Sükhbaatar, defeated the White warlord and established a new pro-Soviet Mongolian client state. By 1924, it had become the Mongolian People's Republic. KMT, CCP, and the Chinese Civil War Soviet Foreign Minister Georgy Chicherin played a major role in establishing formal relations with China in 1924, and in designing the Kremlin's China policy. He focused on the Chinese Eastern Railway, Manchuria, and the Mongolian issue. In 1921, the Soviet Union began supporting the Kuomintang, and in 1923, the Comintern instructed the CCP to sign a military treaty with the KMT. But in 1926, KMT leader, Chiang Kai-shek abruptly dismissed his Soviet advisers, and imposed restrictions on CCP participation in the government. By 1927, when the Northern Expedition was nearly concluded, Chiang purged the CCP from the KMT-CCP alliance, resulting in the Chinese Civil War which was to last until 1950, a few months after the People's Republic of China, led by Mao Zedong, was proclaimed. During the war, some Soviet support was given to the CCP, who in 1934 were dealt a crushing blow when the KMT brought an end to the Chinese Soviet Republic, beginning the CCP's Long March to Shaanxi. Second Sino–Japanese War and World War II In 1931, the Empire of Japan invaded Manchuria and created the puppet state of Manchukuo (1932), which signalled the beginning of the Second Sino–Japanese War. In 1937, a month after the Marco Polo Bridge Incident, the Soviet Union established a non-aggression pact with the Republic of China. During the World War II-period, the two countries suffered more losses than any other country, with China (in the Second Sino–Japanese war) losing over 35 million and the Soviet Union 27 million people. Joint-victory over Imperial Japan On August 8, 1945, three months after Nazi Germany surrendered, and on the week of the American atomic bombings of Hiroshima and Nagasaki (August 6 and 9), the Soviet Union launched the Soviet invasion of Manchuria, a massive military operation mobilizing 1.5 million soldiers against one million Kwantung Army troops,