Because of World War II there was an agreement between the United States, Great Britain, and the Soviet Union called the Yalta agreement. This agreement was not to be as it was originally viewed. The agreement was brought to view to bring the Soviet Union to declare war on Japan, thus becoming an ally with the United States and Great Britain. The agreement promised the Soviet Union to gain back control of the European territories that the Soviet had lost during a different war in 1905 known as the Japanese War. The United States was motivated because they feared that the Soviet Union was going to take over and gain much power. The Soviet Union was afraid that Germany was going to take control and have power and taking over like was planned
