After World War II (1939–45), an intense rivalry developed between so-called Eastern bloc countries (made up of the Communist Soviet Union and its allies) and the Western bloc countries (the United States and its democratic allies). Though mutual suspicion, distrust, and fear ran deep on both sides of the conflict, the Cold War (1947–89) never resulted in fighting: it never became “hot.” But both sides nevertheless prepared for that possibility by strengthening military alliances and developing and stockpiling weapons. The Cuban Missile Crisis (1962) was probably the closest the Cold War came to getting hot.