Despite their shared communist ideology, China and the Soviet Union were hardly close friends and committed partners during the Cold War.
Petulant competitiveness defined the irrelationship, as they squabbled over Mongolia and Manchuria and jostled for leadership of the communist world. A similar dynamic was reflected in Chinese President Xi Jinping’s recent visit to Moscow, with one crucial difference.
Of course, there was plenty of collaboration between the USSR and China. Both backed Kim Il Sung’s communists in the Korean War and the Chinese helped to uphold the Kremlin’s East European sphere of influence. (Albania was loyal to China, while Josip Broz Tito’s Yugoslavia used China as leverage to extract concessions and support from the Kremlin.) Moreover, Soviet scientists and engineers worked in China, with the Soviets agreeing in 1957 to help the People’s Republic acquire atomic capabilities.