The Korean War: Partition, Invasion, and Global Impact

The Korean War: Origins of Conflict

The Korean War began following the post-World War II partition of the peninsula, which had been ruled by Japan since 1910. In 1945, Soviet and American troops occupied the territory, divided along the 38th parallel.

The Division of Korea (1945–1948)

• In North Korea, indigenous Marxists under Kim Il-sung took control with Soviet assistance and began organizing a totalitarian state.
• In South Korea, General John R. Hodge began establishing defense forces and police, moving toward a separate administration.

By the time Washington and Moscow focused on Korea, the Cold War had already set in, and the de facto partition became permanent. South and North Korean governments arose in 1948, each claiming legitimacy for the whole country and threatening to unify Korea by force. Between October 1949 and June 1950, thousands of soldiers were killed in border incidents along the parallel.

The Invasion and Acheson's Defense Perimeter

In January 1950, Secretary of State Dean Acheson outlined his Asian policy in a speech before the Press Club in Washington, D.C. He included Japan, Okinawa, and the Philippines within the American line of defense. Five months later, in June 1950, North Korea invaded across the 38th parallel.

Conventional wisdom suggested that Kim was acting on Stalin's orders and that Acheson's omission of Korea from the defense perimeter had “invited” the attack. However, the U.S. had not ignored Korea; its south was considered vital to the defense of Japan, but the U.S. did not intend to station its own forces there. Acheson was trying to prevent a wider war.

Stalin's Role in Encouraging the Attack

Stalin did not behave the same way as he did with his other client states. He did not want to expose North Korea to a U.S. counterattack, but Kim acted in his own pursuit of a unified national communist state. Stalin might have encouraged North Korea to attack in order to keep Kim dependent on the USSR.

UN Counterattack and Chinese Intervention

In September 1950, General Douglas MacArthur's landing at Inchon was followed by President Truman's approval of operations north of the 38th parallel. Soon, UN forces were driving through North Korea toward the Yalu River border with China. In November, Chinese forces attacked across the Yalu, dramatically escalating the conflict.

Global Repercussions of the Korean War

The effects of the Korean War reverberated around the world, solidifying Cold War alliances:

• Acheson agreed in September 1950 to contribute U.S. divisions to a NATO army under the command of General Eisenhower.
• The Truman administration persuaded Congress to commit four additional divisions to Europe, strengthening NATO's presence.