Causes of the Korean War (AQA A-Level History): Revision Notes
Causes of the Korean War
The division of Korea in 1945
At the Potsdam Conference in August 1945, the Korean peninsula was removed from Japanese control and split into two areas occupied by different powers. The division followed the 38th parallel, with Soviet forces controlling the north and American forces controlling the south. This arrangement bore some resemblance to Germany's partition, though Korea appeared less important to the superpowers at the time.
The division of Korea mirrored the partition of Germany, creating two distinct zones of influence. However, unlike Germany, Korea initially received less attention from the superpowers, making the establishment of separate governments seem more deliberate than circumstantial.
Despite the seemingly temporary nature of this division, both superpowers moved to establish separate governments in their respective zones. In August 1948, the USA organised the creation of the Republic of Korea (ROK) in the south. The Soviet Union followed a parallel course in the north, establishing the Democratic People's Republic of Korea (DPRK) in September 1948.
Truman sought to prevent Soviet control of the entire Korean peninsula as Soviet forces liberated it from Japanese occupation. American forces had just completed defeating Japan in the Pacific, making Korea vulnerable to Soviet influence. Stalin consented to Truman's proposal to divide Korea, but the USSR moved swiftly to treat North Korea as an area within its sphere of influence.
The position and aims of Korean leaders
Both the USA and USSR installed leaders whom they believed they could control in their respective zones.
Kim Il Sung's communist vision
Kim Il Sung became chairman of the Korean Provisional People's Committee (NKPPC), which functioned as a provisional communist government. The Soviets deliberately avoided forming any coalition that included non-communist groups.
Kim Il Sung (1912-94) brought extensive experience in nationalist resistance. He had fought against Japanese occupation before fleeing to the USSR, where he became a possible leader of post-war Korea. Though communist, he was not simply a puppet of the USSR or China. He exploited Korea's growing importance in the emerging Cold War environment of the late 1940s.
Both Korean leaders committed themselves to reunifying Korea under a single authority. A 1948 CIA report stated that Rhee had devoted his whole life to achieving an independent Korea with the ultimate objective of personally controlling the country, and that he showed willingness to use any means necessary for personal advancement, with one important exception: he consistently refused to work with communists.
Kim Il Sung adopted an uncompromising position. He committed to using force to achieve reunification through extensive guerrilla action by the North.
Understanding Guerrilla Warfare
Guerrilla action involved fighting using 'undercover' methods of attacking a stronger enemy. Guerrillas often set traps and used ambush tactics rather than engaging opponents through traditional military methods, giving them a greater chance of success against conventionally superior forces.
These tactics aimed to destabilise the South and undermine Rhee's regime. The South proved equally determined to use force, both to defend itself and to attack the North. In late 1949, Rhee expressed confidence that a major assault against the North could succeed, making reunification easier to defend than the existing division. Kim Il Sung remained fully aware of the broader Cold War context, understanding the importance of the Soviet Union's nuclear technology and the possible consequences for North Korea in its relationship with the US and Japan.
Kim Il Sung developed a strategy based on securing external support. He wanted to harness the collective power of the communist world to increase the North's strength against South Korea and its Western allies. He focused on four arguments to persuade Stalin to support an attack on the South:
- The attack would achieve rapid and decisive victory
- A core of 200,000 communist supporters already existed in the South
- A well-organised communist guerrilla force was operating in the South
- The USA would not have sufficient time to intervene
Kim Il Sung's Diplomatic Strategy
Kim Il Sung employed identical tactics with China. He attempted to undermine Stalin's support when negotiating with Mao Zedong, and similarly worked to weaken Mao's support when speaking with Stalin. This diplomatic maneuvering demonstrated his skill in playing the two communist powers against each other to secure maximum support for North Korea.
Syngman Rhee's anti-communist nationalism
Syngman Rhee became the USA's preferred anti-communist leader. Rhee (1875-1965) had maintained a long association with the USA, having lived there for approximately 40 years. He proved himself a skilled propagandist for Korean nationalism within what appeared to be a democratic framework. Elements of the US government strongly supported him. As a committed nationalist, he grasped the nature of post-war international relations thoroughly and used this understanding to benefit both his own position and South Korea's interests.
Rhee combined nationalist and virulent anti-communist views. He wanted to reunify Korea as a sovereign country that would not tolerate communism in any form. This meant removing communism from the North whilst simultaneously establishing a stronger state capable of resisting any threats from the USSR. He argued that defending a border with Manchuria would prove more effective than defending a border at the 38th parallel. Rhee required a guarantee from the USA that it would protect South Korea from a northern attack and provide military aid to enable the South Korean Army to enforce national reunification.
Rhee's extensive time in the USA (approximately 40 years) gave him unique insight into American political culture and decision-making processes. This experience made him particularly effective at securing US support and framing Korean issues in ways that resonated with American foreign policy concerns during the early Cold War period.
The USSR's changing position
In March 1949, Kim Il Sung approached Stalin for Soviet support for a North Korean assault on South Korea. Stalin demonstrated acute awareness of the presence of 7500 US troops still stationed in South Korea. He rejected Kim Il Sung's plans, but suggested Kim Il Sung should strengthen the guerrilla forces in the South to undermine the government there.
By February 1950, Stalin's position had shifted as the international scene changed during this period. Chinese communists had defeated the nationalists and established the People's Republic of China. The Americans had incorporated South Korea into their Defensive Perimeter Strategy. For these reasons, Stalin agreed to provide North Korea with 1600 pieces of artillery, 178 military aircraft and 258 T-34 tanks.
The Shift in Stalin's Position
Between March 1949 and February 1950, two major developments transformed Stalin's strategic calculations:
- The communist victory in China created a powerful communist ally in East Asia
- The US announcement of its Defensive Perimeter Strategy, which excluded South Korea from the list of territories the US would automatically defend
These changes made Stalin more confident that North Korea could succeed without triggering direct US-Soviet confrontation.
Stalin was not prepared to commit Soviet troops to participate in a war. He maintained several priorities which influenced his thinking:
Stalin's Strategic Concerns
A war in Korea might draw in the USA, potentially leading to a US-Soviet conflict that could spread into Europe. Stalin did not anticipate a global conflict but remained conscious that Europe represented the epicentre of Cold War confrontation at this time.
This explains why Stalin provided military equipment but refused to commit Soviet troops—he wanted to support North Korea while maintaining plausible deniability and avoiding direct confrontation with the United States.
Key Points to Remember:
- Korea was divided at the 38th parallel in August 1945, with the USSR controlling the north and the USA controlling the south. Both superpowers established separate governments in 1948.
- Kim Il Sung committed to reunifying Korea under communism through force, including guerrilla warfare. He sought support from both the USSR and China by emphasising the prospects of quick victory.
- Syngman Rhee pursued reunification by eliminating communism from Korea. He wanted US military aid and guarantees of protection against northern aggression.
- Stalin initially rejected Kim Il Sung's request for support in March 1949 but changed his position by February 1950, providing substantial military equipment whilst refusing to commit Soviet troops.
- The changing international context (Chinese communist victory in 1949, US Defensive Perimeter Strategy) influenced Stalin's decision to support North Korea, though he remained concerned about triggering a broader US-Soviet conflict.