The United States and the Soviet Union cooperated with one another as allies during World War II, sharing a focus especially on defeating Germany. But their alliance was based on a common enemy, not on a common ideology. After the war, the United States viewed the Soviet Union with much suspicion. The two nations distrusted each other and were often at odds -- beginning with incidents like the Berlin Blockade and Berlin Airlift, and continuing throughout what would become known as the Cold War.