Quick questions on The Korean War explained: N(A)-Level History

Korea had been divided after the Second World War into two parts. The north became a communist state, supported by the Soviet Union and later communist China. The south became a non-communist state, supported by the United States. The two Koreas were hostile to each other, and each claimed the right to rule the whole country.

In 1950 communist North Korea launched a surprise invasion of non-communist South Korea, sweeping deep into the South and almost conquering it. The United States saw this as a clear act of communist aggression. American leaders feared that if South Korea was allowed to fall, communism would be encouraged to spread to other countries in Asia. So, true to the policy of containment, the United States decided it had to act to stop the communist advance.

The United States took the matter to the United Nations, the international organisation set up after the Second World War to keep peace. The United Nations agreed to send forces to defend South Korea against the invasion. Although many countries contributed, the force was led by the United States. This gave the Western response international backing and made it look like the world community, not just America, standing up to aggression.

When the United Nations forces advanced far into North Korea, approaching the border with communist China, the Chinese became alarmed. China then entered the war on the side of North Korea, sending huge numbers of troops who pushed the United Nations forces back again. This turned the war into a long and bloody struggle, with the front line moving up and down the country. It also showed how a local war could quickly draw in other powers and become a wider Cold War conflict.

Explain what the war showed about the Cold War spreading to Asia and about containment, not just the fighting.