Causes of the Korean War: Cold War, China, and the USSR

Background: Korea's Post-War Partition

Korea won independence after the Second World War but was partitioned between Russia in the north and the United States in the south. Russia had entered the war against Japan just before the Japanese surrender in 1945, and as a result its army occupied much of Manchuria and the Korean Peninsula north of the 38th Parallel, while American forces were stationed south of it. This situation was stabilized by the Yalta Agreement, which was intended only as a temporary resolution until a Korean government could be elected.

The basis of the conflict that was to come lay not only in the distrust between the USSR and the United States, but was also fostered by underlying political contention between North and South Korea. The Russians in the north and the Americans in the south both installed political leaders who reflected their respective political and social viewpoints — leaders who each wanted to control the whole of Korea. The communist Kim Il-sung was installed as leader in the North, and Syngman Rhee was made leader in the South. Each of these leaders began "...trying to spread their influence to the other side as soon as installed in 1946" (Evanhoe).

Against the background of this internal political strife, there was a larger political and ideological conflict between capitalism and communism that formed the underlying basis for war. This was exacerbated when communists throughout the world began attempting to extend their power and influence. "North Korea's invasion followed a series of Communist advances around the world, including the 1949 revolution in China" (Kalajian).

Efforts were made to normalize the growing tension in the region, and in 1948 an attempt was made to hold elections throughout the country. This failed mainly because North Korea refused to allow voting observers while demanding full observer access to voting in the South. The result was that both North and South Korea declared victory in the election, and each declared its government the true representative of the entire Korean people. Against this background there was a growing military buildup on both sides, each government aided by its respective supporters — the Russians and the Chinese in the north, and the Americans in the south.

It is significant that the Chinese were involved militarily at this early stage. They released more than 30,000 experienced Korean troops who had been fighting with the Chinese Communists to form the core of the North Korean army (Evanhoe). The Soviet Union also provided equipment, aircraft, and tanks to bolster this force. The United States began enhancing South Korean forces as well, but to a far lesser degree.

In 1949, both US and Soviet troops left Korea, leaving only small advisory groups behind. The North Koreans believed that the United States would probably not come to South Korea's aid and decided to invade. There was a vast disparity in the forces, and North Korea possessed overwhelming military superiority. North Korea had a 90,000-strong, well-trained army — with one in three men a combat veteran — equipped with tanks, artillery, aircraft, and ships, plus a 45,000-man reserve. South Korea had approximately 50,000 men, few of whom were veterans, and most were poorly trained, equipped, and armed. South Korea had no tanks, only a few outdated 75mm artillery pieces, about two dozen 105mm artillery pieces, limited ammunition, a few LST landing craft, one patrol craft, and no combat aircraft (Evanhoe).

At the moment of invasion, the United States decided to support South Korea. The Korean War proved to be one of the most destructive conflicts of the twentieth century. Casualties were staggering: an estimated four million Koreans died, two-thirds of them civilians; Chinese casualties are estimated at one million; and over 54,000 Americans were killed, with 103,000 wounded (Korean War).

The Korean War is also known as the "forgotten war." One reason for this label is that it took place less than five years after the end of World War II, and it "was often and perhaps unavoidably compared with and subsumed by the myth and memory of the Second World War" (Pierpaoli). The relationship between the Korean War and the Cold War, particularly in terms of political and ideological thinking, is made clear in the following observation:

...the Korean conflict seemed to have emerged like an unwanted mutation from a linear, Darwinian-like process that seamlessly linked World War II with the Cold War and its early evolutionary process. Thus, from the start, the Korean War became a prisoner of the rigid mentality and ideology of the early Cold War. (Pierpaoli)

The Causes of the Korean War

The real causes of the Korean conflict are a complex amalgam of factors that coincided within a particular historical timeframe. First, the end of the Second World War created a power struggle as well as an ideological struggle between countries with opposing visions of society. Second, the advent of the Cold War was a central factor in the decision to go to war in Korea. It can also be argued that the desire for world dominance on the part of various powers — including the USSR and America — created the climate for war. There are many other contributing aspects, including economic necessities and America's dependence on Asian economies. All of these point to the fact that the history of the Korean War is firmly rooted in the power struggle and mutual distrust that emerged from the Second World War.

To understand the underlying causes of the Korean conflict, it is also important to grasp the wide and complex political thinking of the era. America not only sought to preserve capitalist independence but also viewed this region of the world as a potential partner in its conflict against Russia, and there is a case to be made that American economic motives played a role as well:

The American involvement in the Korean War fit into a larger schema that viewed Northeast Asia as an integral part of the United States' imperative to maintain and expand liberal capitalism around the world. In this sense too, Japan (and by extension Korea) lay at the epicenter of America's sphere of economic dependency in Asia. (Pierpaoli)

Nevertheless, the central reason given by many historians is that the rationale and impetus for the Korean conflict lay in the underlying confrontation with Russia and fear of its expansionist motives. President Truman's government was acutely aware of this and saw the invasion of South Korea as a line that must not be crossed:

In 1945, the United States and its allies bulldozed Germany with overwhelming force and vanquished Japan with two atomic bombs. By 1950, one of our wartime allies had become our greatest threat. The Russians occupied Eastern Europe and built their own bomb. Then they blockaded Berlin, and their fellow communists took over China. The pressure was on Truman to draw the line — but where? (Kalajian)

To a large extent, the invasion from North Korea came as a great shock to the American government and caused a radical shift in US foreign policy. Before the invasion, American foreign policy had been based on containment through treaties and political processes rather than military means. The North Korean invasion changed all of that:

Prior to the Korean War, initiatives such as the IMF, the Marshall Plan, GATT, and even NATO would feature economic and political — rather than military — containment of the Soviet Union. The shock of the North Korean invasion and the American decision to intervene in Korea led to the militarization of containment and resulted in a sustained, if sometimes episodic, militarization of American foreign policy. (Pierpaoli)

Conclusion

Russian influence was certainly part of the overall cause of the Korean War. The Soviet government was pursuing an expansionist strategy across many theatres. It is unlikely the Korean War would have started without the perception of the communist threat and awareness of Russia's expansionist ambitions. The consensus among researchers indicates that the Russian role in the Korean War was an extension of that strategy:

The USSR also went to war because of the Cold War. Stalin wanted to see communism expand as long as he did not get involved in a "hot war" with America. In 1949, Kim Il-sung visited Stalin. He persuaded Stalin that he could conquer South Korea. Stalin did not think that America would get involved, so he gave his agreement. Kim Il-sung also went to see Mao Zedong, the leader of China, to get his support. (Why did the Korean War break out in 1950?)

From a general historical perspective, Russia — through its political strategies and anti-American rhetoric — was more influential than China in starting the Korean War. Stalin's rhetoric was becoming increasingly critical of the West, asserting that World War II was solely the fault of the capitalist system and that without change there would be similar crises and military catastrophes. The growing aggressiveness of Soviet rhetoric, combined with Soviet advances in Iran and Turkey, fueled increasing fear of communist influence throughout Europe (Hannigan).

It was this dimension to which the United States reacted most strongly. The fear of global communist dominance was the most prominent cause of the war — notwithstanding the many other complex factors involved.

From a general historical point of view, it could be argued that in real terms, and in an ideological sense, Russia — through its political strategies and anti-American rhetoric — was more influential than China in starting the Korean War. China, however, played a decisive role in shaping the military course and outcome of the conflict. The Korean War was not the product of a single cause but rather of an interlocking set of factors: the post-World War II partition of Korea, the installation of rival political leaders, the ideological contest between capitalism and communism, Soviet expansionist strategy, American fears about the global spread of communism, and China's own security concerns along its northeastern border.

What is clear is that the Korean War was deeply embedded in Cold War tensions and cannot be understood apart from them. The militarization of American containment policy that resulted from the conflict reshaped US foreign policy for decades. Whether viewed through the lens of Soviet expansionism, Chinese national security calculations, or the competing ambitions of Kim Il-sung and Syngman Rhee, the Korean War stands as one of the defining and most consequential conflicts of the twentieth century.