In the early 1950s, Moscow provided advisers and financial support for China??? new Communist leaders. But after Joseph Stalin died in 1953, the Sino-Soviet relationship deteriorated steadily over differences in ideology and international relations.

Tensions escalated into military buildups along the Sino-Soviet border. After armed clashes erupted between Chinese and Soviet forces along China??? northeast border, many observers predicted war. Ultimately, both sides backed down. But Mao had come to realize that he could not confront both the USA and the Soviet Union simultaneously and determined that Moscow posed the greater threat.

Here, a People's Liberation Army soldier stands guard by a poster of Chairman Mao in China's Xinjiang region on the Soviet-Afghan border in April 1969.