The military strength of the Soviet Union was remarkable. The Soviet Union played a large role during World War II, helping the Allies win the war. Such military strength meant that other regions became more concerned about the capabilities of the nation.
Several other countries began to worry about the possibility of the Soviet Union spreading the ideas of communism all over the world. They were also concerned about the possibility of the country attacking those who refused to follow their ideals. The Soviet Union was also a source of concern because it was known that they had access to nuclear weapons. These elements meant that many countries in the world (particularly the United States) began to think of the Soviet Union more as a more dangerous and threatening menace, and less as an ally.
The treaty of Versailles blamed the Germans for causing the war, even though it was the Austrians who started the war. The answer is that the allied powers blamed The Empire of Germany.
