High Quality Content by WIKIPEDIA articles! The Sino-Soviet Treaty of Friendship, Alliance and Mutual Assistance, or Sino-Soviet Treaty of Friendship and Alliance for short, is the treaty of alliance concluded between the People's Republic of China and the Soviet Union on 14 February 1950, after difficult negotiations in Moscow between Mao Zedong and Joseph Stalin. The treaty did not prevent relations between Beijing and Moscow from drastic deterioration in the late 1950s - early 1960s, at the time of the Sino-Soviet split. The treaty expired in 1979, which allowed China to attack Vietnam, a Soviet ally, in the Third Indochina War as a response to Vietnam's invasion of Cambodia, as the treaty had prevented China from attacking Soviet allies.