The reasons why the Cold War between the USA, the Soviet Union and other participants started were complex and hard to identify independently. The main reason was the ideological difference between the two models of society. The first one was socialistic and the second one was capitalistic. The causes of the Cold War included the struggle for the spheres of influence of the USA and the Soviet Union. Both sides wanted to expand their powers on other territories. The USA and the USSR supported different regimes and in some places, it turned into the local wars. Among the other reasons, scientists mention the refuse of the Soviet Union to become a part of the UN, the support of the allies of western countries of the Atlantic Charter in the year 1941, the mutual fear of the USSR and the USA of their nuclear weapons. Also one of the reasons for the Cold War was the Soviet wish to promote and spread communism all over the world. The American reaction on the threat of communism was the creation of NATO in 1949. Even before that event, the USA decided to restrain the Soviet Union after their shown motives in Greece and Turkey where the USSR wanted to have their military bases. The Truman Doctrine finally ended the previous cooperation between the countries in 1947.
The USA was involved in the Korean and Vietnam wars because of their fear that the communistic regime will get strategically useful places there after its spread all of the countries’ territories. The Korean Peninsula happened to be separated into two parts and two countries. The Soviet Union together with China supported North Korea and the USA supported South Korea. The participation of the USA in the Korean war was another stage of the confrontation with the communistic ideology of the USSR. The same was during the Vietnam war where the USA fought against the communist principles which were being planned to grow there after the achievement of independence. Americans supported South Vietnam in that war. By the year 1966 more than two hundred thousand troops were sent to Vietnam from the side of the USA.