QUICK ANSWER
The main concern of the United States and the other western powers during the Cold War was that the Soviet Union would obtain control of the Western European countries through either invasions or by communist takeovers of unstable governments. Neither side was ever directly engaged in a full-scale armed combat, and the doctrine of mutually assured destruction, or MAD, prevented either faction from using their heavily armed nuclear arsenals. Psychological war, propaganda, proxy wars and espionage were the primary means of each side's struggle for dominance in post-World War II Europe.
