Grigori Voitinsky played an important role in the establishment of the Chinese Communist Party (CCP) in 1921 through the Comintern.

[citation needed] Sun Yat-sen welcomed the Soviet support, which assisted the KMT in fighting the northern warlords.

[4]: 26 In 1926, KMT leader Chiang Kai-shek abruptly dismissed his Soviet advisers and imposed restrictions on CCP participation in the government.

By 1927, after the conclusion of the Northern Expedition, Chiang ended the First United Front between the CCP and Kuomintang, resulting in the Chinese Civil War which would last until 1949, a few months after the proclamation of the People's Republic of China by Mao Zedong.

[citation needed] In 1931, Japan invaded Manchuria and created the puppet state of Manchukuo (1932), which signaled the beginning of the Second Sino-Japanese War.

In August 1937, a month after the Marco Polo Bridge Incident, the Soviet Union established a non-aggression pact with China.

Joseph Stalin viewed Japan as a potential enemy, and as a result offered no help to Chinese communists between 1937 and 1941, in order not to weaken efforts of the Nationalist government.

[citation needed] On 8 August 1945, three months after Nazi Germany surrendered, and on the week of the atomic bombings of Hiroshima and Nagasaki by the United States, the Soviet Union launched the invasion of Manchuria, a massive military operation mobilizing 1.5 million soldiers against one million Kwantung Army troops, the last remaining Japanese military presence.

[11][12] Stalin was focused on European matters and sought Mao's assistance in supporting the Vietnamese Communists against France in the First Indochina War.

As Mao Zedong thought that the usage rights of the Chinese Eastern Railway, the South Manchuria Railway, the Port Arthur and Dalian were part of Chinese state sovereignty, he required the Soviet Union to return these interests to China, and this was a crucial part of the Sino-Soviet Treaty of Friendship.

[14] In the early PRC, Gao Gang and the Northeast People's Government had major roles in conducting the China's relations with the Soviet Union.

As the two leaders distrusted each other, Stalin agreed with sending Chinese troops to Korea, but refused to provide air cover.

[16] Mao sending Chinese troops to take part in the Korean War was followed by large-scale economic and military cooperation between China and the Soviet Union, and the friendly relationship of the two countries changed from titular to virtual.

In one less known example of the Sino-Soviet military cooperation, in April–June 1952 a group of Soviet Tupolev Tu-4 aircraft were based in Beijing to perform reconnaissance missions on United States fusion bomb tests in the Pacific.

By the late 1950s, the Soviets had erected a network of modern industrial plants across China, capable of producing warplanes, tanks and warships.

[citation needed] In 1976, Mao died, and in 1978, the Gang of Four were overthrown by Hua Guofeng,[21] who was to soon implement pro-market economic reform.

With the PRC no longer espousing the anti-revisionist notion of the antagonistic contradiction between classes, relations between the two countries became gradually normalized.

Hundreds of millions worth of anti-aircraft missiles, rocket launchers and machine guns were given to the mujahideen by the Chinese.

[24]: 141  The deaths of Soviet leaders Leonid Brezhnev (in 1982), Yuri Andropov (1984), and Konstantin Chernenko (1985) provided the opportunity for Sino-Soviet "funeral diplomacy" and an improvement in relations.

[25] Soviet-educated and Russian-speaking Vice Premier Li Peng attended Chernenko's funeral and met with Soviet leader Mikhail Gorbachev twice.

[26] Chinese leader Deng Xiaoping wanted to reduce tensions with the Soviet Union to facilitate focusing resources on economic development.

[27] Unlike that of the PRC, this was a much more extreme, highly unregulated form of privatization which resulted in massive losses to foreign speculators, near-anarchical conditions and economic collapse.

Nor was the PRC's desperate and ever-growing need for mineral resources, especially petroleum fuel, which the Soviet Union held in abundance in such Asiatic regions as Western Siberia.