Cold War was the result of ideological differences which rose in the post-world war era. One ideology was capitalist led by USA and another was communist headed by USSR. The cold war between these two superpowers had begun informally in 1917 with the outbreak of Bolshevik revolution and lasted till the disintegration of Soviet Union in 1990. Its main phases were the following :

1. First Stage (1917-1945 AD) 

• Communist government was established in Russia by Bolshevik revolution in 1917 CE. 
• After that the incidents such as establishment of control over eastern European Nations by Soviet Union, holding a different view regarding acquisition of Italy by Germany, raising voice agaisnt the bombardment of Japan by USA, etc. laid the foundation of Cold War.

2. Second Stage (196 CE-1953 CE) 

• In 1948, western Germany was separated from eastern Germany by USSR,
• In 1949 North Atlantic Treaty Organisation (NATO) was established under the leadership of USA as an armed force. Through NATO a message was given to Soviet Union that attack on any member of NATO would invite wrath of itself, 
• In the same year communism was established in China and it accelerated the conflict between USA and Soviet Union over the issue of admission of China in UNO. 
• The bitterness turned into hostility finally in 1950 when communist North Korea attacked capitalist South Korea.

3. Third Stage (1953-1958 CE) 

• USSR tested its first nuclear device in 1953. 
• To check the spread of Russia, President Eisenhower of America formed SEATO (South East Asian Treaty Organisation). 
• The USSR retaliated this move by forming a communist defense pact consisting of Eight nations known as Warsow Pact in 1955. It was an answer to NATO, o In the opposition of communist Russian invasion, American Senate passed a bill regarding privilege for President. 
• Russia criticized the attack on Egypt in 1956. Due to this, tension was created between these two superpowers.

4. Fourth Stage 

• In May 1960, a helicopter of America was caught manouvering on the borders of Soviet Union. This event led to the failure of Paris conference, 
• In 1961, Berlin wall crisis and rise of Fidel Castro of Cuba were the main events of Cold war.

5. Fifth Stage (1963-1979 CE) 

• In 1963, America and Russia signed ‘Hotline Agreement’. According to which in the time of emergency, they would communicate through radio and telephones, 
• in 1968, they both signed Nuclear Non-Proliferation Treaty (NPT). 
• In 1971, America, Soviet Union, Britain and France signed treaty to allow the movement of people from western to eastern Germany and Vice-versa. 
• In 1971, Indo-Pak war, America favoured Pakistan and Russia favoured India, 
• In 1973, 1974 and 1977, three European security conferences were convened for mutual cooperation and peace in the countries.

6. Last Stage 1980-1990 AD 

• In 1983, Soviet Union destroyed a South Korean plane. This was condemned by the US. 
• In 1986, Soviet Union conducted Nuclear Test after removing restriction from itself. It also warned Ameria not to retaliate back. 
• In 1989, Germany was unified again.

Thus, due to continuous Cold War Soviet Union became financially weak and lost the power to remain in conflict with America. So in the reign of President Mikhail Gorbachev, Soviet Union disintegrated in 1990, and along with it the Cold War came to end.