It is interesting to note that the official Peace Treaty of San Francisco, ending WW2 was not signed by the USSR, the People’s Republic of China, nor the Republic of China (Nationalists). The two Chinas were not even invited to the Conference, and while the former Soviet Union sent representatives, they never signed it. The former USSR also most likely influenced both the Czechs and the Poles who also refused to sign. See: San Francisco Peace Treaty The Japanese and the new Russian Federation are getting close to signing an official peace treaty, but the dispute over the Kuriles and other territories seem to be put aside for the time being. See: Russia, Japan to avoid linking peace treaty signing to other issues | Top Russian news and analysis online | 'RIA Novosti' newswire The former USSR did sign a separate paper which allowed them to establish formal diplomatic relations with Japan, and the People's Republic also signed a separate paper with the Japanese for the same purpose.
FRUS: Foreign relations of the United States : diplomatic papers, 1945. General : the United Nations (Volume I): The United Nations conference on international organization, San Francisco, California, April 25-June 26, 1945
