Stalin needed the support of the Allies to secure his victories in Eastern Europe and in Asia. During January 1945, Stalin promised to uphold the Yalta Conference's “Declaration on Liberated Europe,” which guaranteed that open elections would be held in the Eastern European countries under his control. But Stalin quickly broke his promises in Europe, and in Asia too. For example, on 11 January 1943, the United States and Great Britain had completely eliminated all of their remaining extraterritorial rights and special privileges in China. But during the same year, Chiang Kai-shek for the first time confirmed that “the Sino-Soviet Agreement concluded on the basis of equality was not fully carried out.”1 Following the end of World War II, the Soviet government did not renegotiate its unequal treaties with China, but instead worked hand in hand with the Chinese communists to overthrow the Kuomintang. Stalin also consolidated Soviet control over Outer Mongolia.

Historians have previously attributed Chiang Kai-shek's 14 August 1945 decision to hold a plebiscite granting Outer Mongolia full independence from China to the 11 February 1945 Yalta agreement, in which Roosevelt, Churchill and Stalin decided: “The status quo in Outer-Mongolia (the Mongolian People's Republic) shall be preserved.”2 But when President Roosevelt agreed to support the status quo he never intended to push China into granting Outer Mongolia its independence. In fact, according to international law, the juridical status quo appeared to be based on the 31 May 1924 Sino-Soviet treaty, in which Moscow publicly recognized that Outer Mongolia was an integral part of China: “The Government of the Union of Soviet Socialist Republics recognizes that Outer Mongolia is an integral part of the Republic of China and respects China's sovereignty therein.”

But the true status quo was not what it appeared. China's sovereignty over Outer Mongolia was in fact undermined by a 31 May 1924 secret protocol with the USSR that recognized the 1915 tsarist tripartite treaty signed by Tsarist Russia, China and Outer Mongolia granting Outer Mongolia its autonomy from China. Although the 1924 protocol specified that the 1915 treaty was not to be enforced, Outer Mongolia's de facto autonomy was assured so long as Moscow refused to negotiate new terms. When Roosevelt promised to uphold the status quo at Yalta, therefore, he unwittingly provided Stalin with important leverage during secret Sino-Soviet negotiations that followed the Yalta Conference.