The Korean War and Four Leaders' Divergent Dreams

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This year marks the 75th anniversary of the outbreak of the Korean War. The Korean War is an unfinished war. Instead, it is frozen in a state of armistice. John Mearsheimer, a prominent realist scholar at the University of Chicago, likens the Russia-Ukraine war to the Korean War, diagnosing it as likely to remain a frozen conflict. It is a terrible situation for Ukraine to have the war frozen while having lost a quarter of its territory. The Korean War, frozen in a state of division for 75 years, is similar. A peaceful resolution to the Korean War is crucial for all parties in Northeast Asia, not just South and North Korea. That resolution must begin with the question of why the Korean War has not yet ended. Carl von Clausewitz, a master of war theory, defined all war as a continuation of politics. The beginning and end of war are dictated by the political objectives of the parties involved. The key to the beginning and end of the Korean War lies in examining the political objectives of its main leaders: Kim Il-sung, Syngman Rhee, Truman, and Mao Zedong.

First, the intention of North Korea's leader Kim Il-sung, who initiated the war, was to achieve the unification of South Korea through military force. After the establishment of separate governments in the South and North, there were frequent armed clashes between the two governments, which claimed legitimacy, across the temporary demarcation line of the 38th parallel. The decisive factor for Kim Il-sung's decision to launch a full-scale invasion was the calculation that the United States would not intervene militarily on the Korean Peninsula. Six months prior to the invasion, then U.S. Secretary of State Dean Acheson announced at a press conference that Japan and the Philippines, not the Korean Peninsula, were within the United States' primary defense perimeter. This was later interpreted as the exclusion of the Korean Peninsula from the U.S. defense line in East Asia, known as the Acheson Line. Kim Il-sung secured the support of Stalin and Mao Zedong for the invasion, who were concerned about potential military conflict with the United States.

However, U.S. President Truman decided to intervene just one day after the outbreak of the Korean War. What, then, were President Truman's political objectives for intervening? Throughout the Korean War, the United States appeared to waver in its basic objectives. Initially, the goal was set to protect South Korea from communist aggression and, simultaneously, to severely punish North Korea for its military provocations. Immediately after World War II, the United States established a new world order led by the U.S., with the UN headquarters in New York, defining any form of aggression as illegal. Kim Il-sung's invasion was a direct challenge to the fundamental spirit of the UN and American leadership. Furthermore, the geopolitical and military calculation that Japan, designated by Acheson as a key U.S. defense line, would be endangered if the Korean Peninsula fell to communism also played a role. Later, after General MacArthur's Incheon landing operation in September 1950, the tide of war turned dramatically, and the U.S. advanced into North Korean territory, pursuing unification of the North and South as a new war aim. However, as Mao Zedong felt threatened by the approach of U.S. forces to the Sino-Korean border, he deployed a large number of ground troops in October of that year, reversing the tide of war once again. Consequently, the war aims were again shifted to restoring the original territory of South Korea and seeking a swift end to the war to avoid a full-scale conflict with China and the Soviet Union.

Meanwhile, the Syngman Rhee government in South Korea pursued the goal of advancing north to unify the peninsula, utilizing U.S. intervention. When the tide of war turned with General MacArthur's Incheon landing operation, they dreamed of unification led by South Korea. Even after the Allied forces retreated due to Chinese intervention, Syngman Rhee's political objective persisted. However, President Truman, concerned about a world war with China and the Soviet Union, dismissed General MacArthur, who advocated for the use of nuclear weapons against Chinese forces, and hurried to seek an armistice in the stalemated war. Truman's successor, Republican President Eisenhower, also pursued a swift conclusion to the war, leading the Syngman Rhee government to refuse to sign the armistice agreement. This is why South Korea, despite being a party to the conflict, was excluded from the armistice negotiations, which included China and North Korea, and represented by the U.S. as the UN forces' representative. Subsequently, North Korea adopted a policy of engaging only with the U.S. on military issues concerning the Korean Peninsula, including nuclear matters, while excluding South Korea, known as the 'Tongmi Bongnam' (engaging the U.S., bypassing the South) policy.

Mao Zedong of China decided to intervene, overriding the opinions of his advisors who opposed war with the United States, under the banner of 'Resist America, Aid Korea, Defend the Homeland' (抗美援朝 保家衛國). The solidarity of communist brethren was emphasized, highlighting North Korea's support for China during the Second Sino-Japanese War against the Japanese army. This is why China refers to the Korean War as the 'War to Resist U.S. Aggression and Aid Korea.' However, a more crucial reason was their security concerns regarding the advancing ROK-U.S. forces approaching the Sino-Korean border. 'Defend the Homeland' meant that aiding North Korea ultimately protected one's own home and country. They feared the disappearance of North Korea as a strategic buffer zone in the event of unification led by South Korea. China suffered over 180,000 deaths, including Mao Anying, Mao Zedong's only son, and over 900,000 casualties in the Korean War. Mao Zedong's intention to protect North Korea as a strategic buffer zone against direct U.S. threats has since become the fundamental basis for maintaining Sino-North Korean relations.

The Korean War was a conflict born from the clash of differing political objectives for war held by the leaders of South Korea, North Korea, the United States, and China. Kim Il-sung's goal of unification by force at the beginning of the war and Syngman Rhee's pursuit of unification by advancing north at the end of the war both carried the character of total war aimed at destroying and absorbing the opposing system. The fundamental dynamics of this have not essentially changed today. This is the background for the armistice agreement, rather than a peace treaty, continuing for over 70 years. With the situation being such that the Korean War could restart at any moment, the North and South still live with the risk of total war.

The calculations of the U.S. and Chinese leaders, who played the role of patrons for the North and South, differed. For Truman and Mao Zedong, the Korean War was a burdensome conflict, yet one they could not afford to abandon given the Cold War confrontation and their respective national security interests. Their objective was to avoid full-scale confrontation while preventing the other from gaining dominance over the Korean Peninsula. Truman's intervention and Mao Zedong's full-scale military intervention after the U.S. advance north were strategic gambits to secure their buffer zones under the guise of protecting the North and South. Simultaneously, the Korean War was characterized as a defensive limited war to avoid a full-scale conflict between the U.S. and China. This explains the haste to conclude the armistice agreement once the war reached a stalemate.

The Korean War ended in 1953 not with a victory for anyone, but with an armistice, solidifying the division of the Korean Peninsula. However, the division of the Korean Peninsula had been discussed multiple times before the Korean War. During the Imjin War, the Ming Dynasty, which reluctantly dispatched troops to Joseon, discussed a plan with Japan to divide Joseon into North and South and establish an armistice for a swift resolution. In the late Joseon Dynasty, Russia, competing for hegemony in Northeast Asia with Japan, proposed a compromise to Japan just before the Russo-Japanese War in 1904: dividing the Korean Peninsula along the 39th parallel. The agreement between Russia and the U.S. to establish the 38th parallel after liberation in 1945 may not be a historical coincidence. The division of the Korean Peninsula could serve as a useful compromise mechanism in the great powers' strategy of balancing power to avoid burdensome wars.

The armistice agreement was the product of the clash and compromise between the differing objectives of total war by the North and South and limited war by the U.S. and China. Today, the calculations of the U.S. and China regarding the Korean Peninsula have not significantly changed. In fact, the U.S. and China may feel even more burdened by the prospect of military intervention in a second Korean War than the parties involved on the peninsula. This is because the Korean War was so fierce and the sacrifices were so great. This is why, during military crises between the North and South, China consistently emphasizes stability and dialogue on the Korean Peninsula, while the U.S. hopes for restrained responses from South Korea. In the 21st century, the U.S. and China are engaged in a hegemonic competition not only on the Korean Peninsula but also at regional and global levels. The fact that the political and military interests of the rapidly rising China and the superpower U.S. are the greatest variables determining the war and fate of the Korean Peninsula remains true today.

Following the war in Ukraine, the U.S. has become involved in the Iran-Israel conflict. The Trump administration continues to urge an armistice between Russia and Ukraine, and Iran and Israel. This reflects the desire of great powers to avoid entanglement in regional conflicts. The problem is that armistice and cessation of hostilities are not easy. The lessons of the Korean War from 75 years ago are newly relevant to the geopolitical hegemonic competition of the 21st century. The Korean War, which ended not with a peace treaty but with an armistice after three years of fierce fighting, is still an unfinished war. The military standoff between the North and South, separated by the Demilitarized Zone, remains fundamentally unchanged. South Korea's proactive role in leading the declaration of an end to the war, a North-South peace treaty, and the establishment of a peace regime on the Korean Peninsula, based on democracy and strong deterrence against North Korea, is more crucial than ever. ■

■ Shin Sung-ho_Professor, Graduate School of International Studies, Seoul National University.

■ Editor: Oh In-hwan_Senior Research Fellow, EAI

Contact: 02 2277 1683 (ext. 202) | ihoh@eai.or.kr