The Cold War is a term used to describe the period of openly hostile relations between the USA (and its allies) and the USSR (and its allies) from the end of the Second World War up until the early 1990s. Each 'side' had different political systems. The USSR followed a communist system, while the USA was a capitalist country with a democratically elected government.
Communism:
Communists believe workers should seize power from rich factory owners and businessmen, as happened in Russia in 1917
The government should decide what is made and what it should cost
A strong government should control things on behalf of the people, making sure that all people are equal
All factories, shops and land should be owned by the government - not by individuals who are only concerned with making money
Capitalism:
Capitalists believe that people should be free to own their own property and businesses, and make money for themselves
There are several political parties and people can vote for whichever one they like
Individuals and businesses compete against each other to produce more and make better products using the latest technology
Workers get jobs in factories, in shops, and on land that is owned by businesses or wealthy individuals
The Truman Doctrine and containment
In March 1947, US President Harry Truman said that the USA would come to the aid — with money and military help - of any country under threat of a communist takeover. The USA would 'contain' communism and stop it spreading from country to country.
This policy of containment became known as the Truman Doctrine and was the basis of US foreign policy for years to come.
Stalin was suspicious of the Truman Doctrine. He thought it was a way for the USA to control Europe by offering money in return for trade.
• By 1949, the USSR had developed nuclear weapons.Now, along with the USA, the two most powerful countries in the world each had nuclear weapons.
In the same year, the USA, Britain, France, Belgium, Canada and other European countries formed a military alliance called NATO; this union was a defence against the USSR and its eastern European allies.
The communist countries responded by forming the Warsaw Pact, a military alliance containing the USSR, Albania, Bulgaria, Czechoslovakia, East Germany, Hungary, Poland and Romania.
In the early 1900s, Japan took over Korea; the country remained under Japanese control until the end of the Second World War.
When Japan lost the war, Japanese soldiers in the north of Korea surrendered to Soviet forces, while those in the south surrendered to US forces.
The country was divided into two separate zones - but the division was meant to be temporary. It was intended that Korea should become a united, independent country.
Elections were planned, organised by the United Nations.
In 1948, before UN-organised elections could be set up, the Soviets in the northern zone allowed a Korean communist named Kim II-sung to take power.
Kim lI-sung was a committed communist and Korean nationalist; he wanted a united independent Korea. He had lived in the USSR from 1941 to 1945, serving as a Major in the Soviet army.
He had returned to Korea in 1945 to form the Communist Party of North Korea.
The north became the People's Republic of Korea (or North Korea with Pyongyang as its capital.
In the US-controlled southern zone, elections were held; a capitalist with strong ties to the USA, named Syngman Rhee, became leader.
Like Kim Il-sung, Rhee too was a Korean nationalist.
He had trained as a lawyer in the USA.
He had developed a reputation for being a harsh ruler and his political opponents were quickly crushed.
The south became the Republic of Korea (or South Korea with Seoul as its capital.
The Japanese had invaded China in 1931 and taken control of large parts of the country.
At the time, China was in the middle of a civil war: the government of China (led by Chiang Kai-shek) was fighting communists (led by Mao Tse-tung). The two Chinese sides united to fight the Japanese.
After Japan's defeat in the Second World War (and withdrawal from China), the civil war started again.
The USA supported Chiang Kai-shek and sent equipment to help his forces fight the communists.
But support for the communists was strong in China and in 1949 the communists won.
American fears:
China's emergence as a communist country frightened many Americans who feared the spread of communism
US spies also reported that Stalin was attempting to help communists take control of other countries in the region, such as Indonesia, Burma and the Philippines
Senior US politicians warned President Truman that communists could soon be in control of the whole of Asia; the decision was made to stop any further spread of communism - by force if necessary
Within the United Nations, the big decisions relating to peace and security are taken by the 'Security Council'.
When China became a communist country, the Security Council had to meet to agree to the new Chinese government being allowed to join.
The USSR was keen for communist China to join - but the USA, unsurprisingly, vetoed the decision.
The USA regarded Chiang Kai-shek and his supporters as the rightful government of China. In protest, the USSR stormed out of the meeting and refused to attend Security Council meetings for the foreseeable future.
The UN Security Council
The Security Council has fifteen member states.
Five of these are permanent (Britain, France, the USA, the USSR and China); ten are non-permanent and attend meetings on a rota basis.
For a decision to be made, nine countries must agree, including all five permanent members.
This means that any permanent member can veto a decision.
At this time, the USA and the USSR regularly argued with each other in meetings and often blocked suggestions using their vetoes.