The leaders of the US, USSR, and Great Britain said they wanted to cooperate, so why were negotiations at the Yalta and Potsdam conferences so difficult?

The Allies agreed to cooperate against their common enemies, but they had different visions for the post-war world. The United States and Great Britain favored self-determination and democratic governments, while the Soviet Union wanted security and influence in Eastern Europe. These competing goals made negotiations at Yalta and Potsdam difficult, so B is correct.

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