Held from 4 to 11 February 1945 in the Crimea, the Yalta Conference, sometimes called the Crimea Conference, was the last summit of World War Two that involved Franklin D. Roosevelt, Winston Churchill, and Josef Stalin. Major areas of agreement included policies for the Occupation of Germany and conduct of the war against Japan. The conferees also agreed to create the United Nations. A brief conference on Malta, between Roosevelt and Churchill, preceded it.
"No more let us falter From Malta to Yalta Let nobody alter" Winston Churchill
Many analysts consider Stalin the most important beneficiary of the Conference, playing the Western Allies' need for power against Japan for concessions to the Soviet Uniion.  Others, however, observe that it may have constrained Stalin's already strong position. 
Plans for Japan
As early as the Foreign Ministers' Conference in October 1943, Stalin had been suggesting that the Soviet Union abrogate its nonaggression treaty with Japan and attack, principally as a means of forcing the Western allies to open a second front against Germany. By January 1944, however, Stalin had concluded it was in his country's interest, independent of relations with the West, to go to war with Japan. 
At the time of the Conference, nuclear weapons had not yet been tested and it was expected, by the United States, that it would be necessary to invade Japan. Having Russia open a second front against Japan, therefore, was seen as a need to bring the surrender of Japan. Later, there were regrets that the Soviets would attack on the same day as the Hiroshima attack and thus have grounds for claims against Japan.
Emperor Hirohito had been warned that the neutrality treaty with the Soviet Union was likely to be abrogated. On 16 February 1945, Foreign Minister Mamoru Shigemetsu explicitly warned him that the Yaltha Conference had demonstrated the "unity of Britain, the United States and the Soviet Union." 
"Two or three months after Germany has surrendered and the war in Europe is terminated, the Soviet Union shall enter into war against Japan on the side of the Allies on condition that:
1. The status quo in Outer Mongolia (the Mongolian People's Republic) shall be preserved.
2. The former rights of Russia violated by the treacherous attack of Japan in 1904 shall be restored, viz.:
(a) The southern part of Sakhalin as well as the islands adjacent to it shall be returned to the Soviet Union;
(b) The commercial port of Dairen shall be internationalized, the pre-eminent interests of the Soviet Union in this port being safeguarded, and the lease of Port Arthur as a naval base of the U.S.S.R. restored;
(c) The Chinese-Eastern Railroad and the South Manchurian Railroad, which provide an outlet to Dairen, shall be jointly operated by the establishment of a joint Soviet-Chinese company, it being understood that the pre-eminent interests of the Soviet Union shall be safeguarded and that China shall retain sovereignty in Manchuria;
3. The Kurile Islands shall be handed over to the Soviet Union.
"It is understood that the agreement concerning Outer Mongolia and the ports and railroads referred to above will require concurrence of Generalissimo Chiang Kai-shek. The President will take measures in order to maintain this concurrence on advice from Marshal Stalin.
"For its part, the Soviet Union expresses it readiness to conclude with the National Government of China a pact of friendship and alliance between the U.S.S.R. and China in order to render assistance to China with its armed forces for the purpose of liberating China from the Japanese yoke.
Occupation of Germany
Other European agreements
- The Yalta Conference, Avalon Project, Yale Law School
- S.M. Plokhy (2010), Yalta: the Price of Peace, Viking, ISBN 9780670021413, p. xxii
- Douglas Brinkley, David Rubel (2004), The New York Times Living History: World War II: the Allied counteroffensive, 1942-1945, MacMillan, p. 253
- Tsuyoshi Hasegawa (2005), Racing the Enemy: Stalin, Truman and the Surrender of Japan, Harvard University Press, ISBN 9780674022416, pp. 23-25
- Herbert P. Bix (2001), Hirohito and the making of modern Japan, Harper Perennial, ISBN 978-0060931308, p. 490