Why Did Kim Il-Sung Start the Korean War?
By: Daniel Choi
Tags: History, War, Korean War, Korean History, Korean

Why Did Kim Il-Sung Start the Korean War?

Young Kim Il-Sung delivering a speech (Wall Street Journal)

When North Korea split from its southern counterpart in 1948 through an election Kim Il-Sung felt that he lacked the legitimacy that other communist leaders like Mao and Stalin had. Stalin played a crucial role in the Russian Revolution and was a national hero after winning the Second World War. Mao was leading the communist party of China to a crucial victory against the nationalists that eventually solidified him as the legitimate leader of the nation.

Compared to the two prominent communist figures, Kim lacked both the experience and legitimacy. He had not played a big role in Korea’s independence movement against Japan, and he and the communist party only controlled the northern half of the Korean peninsula. To Kim, unifying the peninsula through an invasion was a crucial milestone that he needed to overcome in order to solidify the legitimacy of his power.

When Kim met with Stalin in Moscow in 1949, Kim expressed his strong desire to invade South Korea. It was reported that Kim told Stalin that he “want[ed] to stab a bayonet in South Korea’s throat.” Although Stalin showed support, he was also very cautious to not provoke the United States. While most American soldiers had left South Korea in 1948, a small military advisory group remained in Seoul, which was enough for Stalin to be cautious of.

The United States Military Advisory Group in Seoul (Military Wiki)

Kim continued to advocate for his plan to invade South Korea by visiting Moscow frequently throughout 1949. Kim believed that he could bring South Korea into submission within a matter of days, not allowing time for the American military to react. However, Stalin feared the American intervention and held off Kim’s request for military advising and support. The year 1949 ended with little fruition for Kim’s ambition.

Circumstances drastically changed for Kim and Stalin in early 1950, when Dean Acheson, the Secretary of State of the United States of America at the time made a speech addressing America’s strategy in East Asia. In the speech that he delivered at the National Press Club in Washington, Acheson excluded Korea from the proposed “Acheson Line” which was an arbitrary strategic line formed across Japan and the Philippines to defend America’s interest against communism. To Stalin and Kim, this meant that America was going to leave South Korea vulnerable to their invasion. By early 1950, a specific plan to invade and subjugate South Korea was being drafted by military strategists in Moscow.

The Acheson Line (Korea Joonang Daily)

Stalin’s certainty that America was not going to intervene did not only come from Dean Acheson’s speech. After witnessing America’s passive attitude towards Mao’s win against the nationalist party and succeeding in developing a nuclear weapon a year prior, Stalin was confident that America was going to avoid waging a war that could end up in nuclear warfare. This turned out to be a crucial mistake for Stalin later on.

In May of 1950, Stalin, Mao, and Kim met in Beijing to discuss and have a formal agreement on their plan to invade South Korea, where Mao promised his support in the case of American intervention. While Stalin and Kim did not worry about possible American intervention, Mao did not exclude the possibility that America was going to try to protect its allies in South Korea and neighboring Japan.

John Singlaub (OCS Alumni)

As North Korea was busy preparing for a war in May of 1950, a CIA agent named John Singlaub noticed that North Korea was quietly moving most of its trained military personnel near the border between the South and the North. He wrote a report to Charles A. Willoughby, who was the intelligence chief for the American commander Douglas MacArthur. In the report Singlaub informed that North Korea was gathering a large army near the border and was building and fixing railways and roads during the night time. Willoughby dismissed this report by deeming it a piece of unreliable information.

America’s complacency and Stalin and Kim’s strong desire to invade South Korea created a perfect opportunity in June to strike. On June 25, 1950, around 4 am, more than 90,000 North Korean soldiers crossed the 38th parallel and invaded South Korea without a formal declaration, commencing a devastating three-year war. Kim’s strive for legitimacy and Stalin’s overconfidence in America’s complacency resulted in a war that killed nearly five million civilians and soldiers.