The Cold war referred to the ideological struggle between the United States and its allies and the Soviet Union and its allies that lasted from 1945 to 1989. During which the two camps struggled to expand and consolidate their respective systems, the capitalist democracy and the communism. It’s characterized with ideological struggle and proxy states. And the cold war ended when the Soviet Union collapsed in 1991.
The first phase of the cold war was characterized with the containment policy and Truman Doctrine. When it became increasingly clear that Stalin was determined to maintain the Russian presence in Eastern Europe, the United States decided to adopt containment to limit as much as possible the spread of communism. And then in 1947, the Truman Doctrine was formulated, the United States announced its support of all “free peoples who are resisting attempted subjugation by armed minorities or by outside pressures. Also to support the doctrine, Truman later announced the Marsh all Plan of aid to Europe, for the recovery of the continent from the ruins of the war. Instead, Stalin engineered fledgling communist governments in Eastern Europe and the Balkans, transforming them into the Communist Bloc and integrating their economies with that of the Soviet Union. In this way, the cold war area expanded.
And the hot war in Korea added fuel to the cold war. The US had long viewed Korea as the key of the cold war. During which, US troops launched some invasions and fought the way back to North Korea and advanced to China border. Also with the establishment of the North Atlantic Treaty Organization(NATO) and Warsaw Pact, more and more countries and nations joined the war. For instance, the Warsaw Pact was jointed by Central and Eastern European Communist states, and they stated that they were all allies and would fight together if one of them was attacked. Moreover, the Cuba missile crisis was the highest period of tension during the Cold War, and it almost led the whole world to a nuclear war.