The Cold War was a prolonged period of military competition and tension between the United States and which nation?

The Cold War was a prolonged period of military competition and tension between the United States and the Soviet Union.

Explanation:

The Cold War was the political and military rivalry that developed after the Second World War between the Eastern Bloc (led by the Soviet Union and comprised of Soviet-friendly regimes) and the Western Bloc (dominated by the United States and comprised of Western European countries and their allies). The era lasted about 40 years; from the late 1940s to the late 1980s.

Eastern bloc and Western bloc countries had different ideologies and economic systems. The Eastern Bloc countries were single-party states with communist societies as their goal, while most Western Bloc countries were multi-party states based on market economy. The conflict was called Cold War because the threat of triggering a global nuclear war between the NATO military alliances and the Warsaw Pact (a "Third World War") led the parties to avoid direct fighting against each other. Instead, the parties provided military and financial support to Allied regimes and waged proxy wars against the counterpart. The Eastern and Western bloc countries carried out intense spy and intelligence activities against each other to gain control of each other. During the Cold War, the superpower's military armament and achievements in aerospace, technology and sports were interpreted as signs of the parties' strength.

Some historians say the end of the Cold War took place in 1989, when the Soviet-supported regimes in Eastern Europe and the Berlin Wall fell. On the other hand, other historians consider that the end of this conflict happened in 1991, when the Soviet Union disbanded. In both cases, the Cold War was won by the Western Bloc.

Answer:Soviet Union