Roosevelt wanted the USSR to join the Allies in the Pacific War against Japan, which he hoped would end the war sooner and reduce American casualties. A Soviet condition for a declaration of war in Japan was an official recognition of China`s Mongolian independence (the Mongolian People`s Republic was a Soviet satellite state from the beginning of 1924 until World War II). The Soviets also wanted recognition of Soviet interests in Manchuria and Port Arthur (but not the Chinese for rent). These conditions were agreed without China`s participation. In Yalta, Stalin accepted Soviet participation in the United Nations, the international peace organization that Roosevelt and Churchill were willing to create in 1941 under the Atlantic Charter. He made this commitment after the three heads of state and government agreed on a plan for a veto for all permanent members of the organization`s Security Council. Churchill had some success at Yalta. One of them was the agreement that France should be invited to occupy an area in Germany and participate in the control commission, a key result given Roosevelt`s determination to limit the length of stay of American troops in Europe. Less concrete, but nevertheless important, Churchill`s hard stance on the defence of freedom and the rule of law, for example in the drafting of the Declaration on Liberated Europe, which called on the three powers to create free elections and democratic governments.
The Soviet Union`s failure to meet its commitments did not diminish Churchill`s efforts to secure them. But he played a weak hand compared to Stalin and even more of Roosevelt. The French head of state, General Charles de Gaulle, was not invited to the Yalta conference or to the Potsdam conference, a small diplomat who aroused deep and persistent resentment.  De Gaulle attributed his exclusion from Yalta to Roosevelt`s long-standing personal antagonism against him, although the Soviet Union also refused his admission as a full participant. But the absence of a French representation in Yalta also meant that De Gaulle`s invitation to the Potsdam conference would have been very problematic. It would then have felt honourable to insist on the need to reopen all the issues agreed upon in Yalta in his absence.  Stalin agreed to admit representatives of other Polish political parties to the communist-dominated provisional government of Poland and to sanction free elections, one of Churchill`s main objectives. Of course, you are right that France was also at war until June 1940; But I was referring in particular to the financial burden of Britain. The debts incurred for the war effort between September 1939 and 1941 (when aid was provided under Lend-Lease) played an important role in Britain`s dire financial situation during the Yalta era.
Allied leaders also discussed the future of Germany, Eastern Europe and the United Nations. Roosevelt, Churchill and Stalin agreed not only to include France in the post-war German government, but also that Germany should assume some, but not all, responsibility for post-war reparations. The Americans and the British generally agreed that future governments of Eastern European nations bordering the Soviet Union should be “friendly” with the Soviet regime, while the Soviets pledged to allow free elections in all liberated regions of Nazi Germany. Negotiators also issued a statement on Poland that presented the Communists` accession to the post-war national government. During discussions on the future of the United Nations, all parties agreed on a U.S. plan on voting procedures in the Security Council, which had been extended to five permanent members after France`s admission.