The causes of the Korean War

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Resolution 83 recommended that members of the UN should give South Korea the help it needed to repel the armed attack from North Korea and restore peace and security in the area.

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Source A opposes the post-war decisions because it attacks the trusteeship agreed by the foreign ministers in Moscow, saying it treats Koreans as if they cannot govern themselves. It compares the four trustee powers to Japan by saying Koreans did not throw off one master to accept four new ones, and it rejects the division of the country by insisting that north and south are 'one people'. It demands immediate independence for a united Korea.

This reflects the situation in 1946. After thirty-five years of Japanese rule, Koreans expected independence in 1945, but instead the country was divided at the 38th Parallel between Soviet and American forces. In December 1945 the Moscow Conference agreed a trusteeship of up to five years under the USA, the USSR, Britain and China. This caused mass protests in the South, led by nationalists such as Syngman Rhee and Kim Ku. The provenance fits this: it is a leaflet from a demonstration in Seoul, written to rally Koreans against the decision.

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Source B is useful because it gives an insider's view of how the decision to invade was made. Khrushchev says that Kim Il Sung proposed the attack, believed the first blow would trigger an uprising against Rhee, and that Stalin did not stop him. This matches what we now know from Soviet documents released in the 1990s: Kim asked Stalin repeatedly in 1949-50, and in April 1950 Stalin approved the plan as long as Mao agreed. Kim did promise Stalin that southern communists would rise up. The provenance adds value, because Khrushchev was one of the Soviet leaders in 1950 and the memoirs were recorded secretly, not as official propaganda. However, he was speaking about twenty years later, from memory, and although he had denounced Stalin in 1956 he still insists the war was 'not Stalin's idea', which may be an attempt to protect the Soviet Union's reputation. In fact Stalin's approval, weapons and advisers were essential, so Source B is useful but may underplay Soviet responsibility.

Source C is useful in a different way. It shows that the South Korean army was organised entirely for defence and could not launch a large-scale attack. This directly undermines North Korea's claim, broadcast on 25 June, that the South had attacked first, and fits the fact that about 135,000 North Korean troops with around 150 T-34 tanks attacked at several points at once. Its provenance makes it very reliable: it was written by neutral UN military observers who had just toured the border, and it was completed on 24 June, the day before the invasion, so it was not affected by hindsight or wartime propaganda. Its limitation is that the observers only saw the southern side, so it tells us nothing about who planned the attack, and it does not mention the border clashes of 1949 in which Rhee's forces also attacked.

Overall, the two sources are most useful together. Source C proves that South Korea did not start the war in June 1950, and Source B explains that the initiative came from Kim with Stalin's agreement. However, neither explains the deeper causes, such as the division of Korea or the rivalry between Rhee and Kim, so an historian would need other evidence to judge responsibility fully.

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The Communist victory in China in October 1949 transformed the situation in Asia, and it helps explain why war broke out in Korea in 1950 rather than earlier. However, it was not the most important reason. The direct causes were Kim Il Sung's determination to reunify Korea and Stalin's decision to support him, which China's revolution encouraged but did not create on its own.

There is a strong case for the Chinese victory. When Mao Zedong proclaimed the People's Republic of China on 1 October 1949, North Korea gained a powerful communist neighbour that could help if an invasion went wrong. This mattered greatly to Stalin, who did not want to risk Soviet troops: when he approved the invasion in April 1950, he made it conditional on Mao's agreement, which Kim obtained in Beijing in May. China's revolution also strengthened Kim directly, as tens of thousands of Korean soldiers who had fought for the Chinese Communists returned to join the North Korean army. The Sino-Soviet Treaty of February 1950 made the communist bloc look stronger and more united than ever.

The victory in China also shaped the American side of the war. In the USA, Republicans accused Truman of 'losing China', and Senator McCarthy's attacks from February 1950 made it politically impossible for Truman to lose another Asian country. The USA's refusal to let Mao's government take China's UN seat led to the Soviet boycott of the Security Council, which allowed the UN to intervene without a Soviet veto. In this sense China's revolution helped turn a Korean invasion into an international war.

However, other factors were more directly responsible. Kim Il Sung was the driving force behind the war: he had asked Stalin for permission to invade in March 1949, before Mao's victory, and kept pressing until Stalin agreed. Stalin's approval was the decisive condition, and it was influenced by several other developments as well as China. US troops had left South Korea by June 1949, the USSR tested its first atomic bomb in August 1949, and in January 1950 Acheson's speech left Korea outside the American defensive perimeter. All of these made Stalin believe that the USA would not intervene. Soviet tanks, aircraft and advisers, not Chinese help, made the invasion possible.

The deeper cause was the division of Korea in 1945. The 38th Parallel, chosen hastily by American officers, hardened into a border between two hostile states in 1948, each claiming the whole peninsula. Syngman Rhee's harsh rule and threats to 'march north', and the clashes along the parallel in 1949, made war increasingly likely regardless of events in China.

In conclusion, I disagree with the statement, although the Chinese victory was very important. It explains why Stalin was willing to take the risk in 1950 rather than 1949 and why the USA reacted so strongly. But it was one of several changes, alongside the Soviet bomb, the US withdrawal and Acheson's speech, that persuaded Stalin, and the war itself came from Kim's ambition to reunify a divided Korea. The Chinese victory was an important trigger, not the main cause.