Korean War

List causes of the Korean War

• Division of Korea

• Stalin’s approval 

• Chinese Communist victory

• Ideological framing

Describe division of Korea

• After Japan’s defeat (1945), Korea was split at the 38th parallel:

• Kim Il-sung led the Soviet-backed north,

• Syngman Rhee the US-backed south.

• Both aimed at reunification under their own system.

Describe Stalin’s approval

Stalin’s approval (Apr 1950):

• Convinced the US would not intervene —

  • after troop withdrawals and Acheson’s “defence perimeter” speech (Jan 1950) omitting Korea —

• Stalin authorised Kim’s invasion,

  • supplying tanks and aircraft.

Describe Chinese Communist victory

Chinese Communist victory (1949):

• Mao’s triumph emboldened Kim

• deepened US fears of a communist “domino effect” in Asia.

Describe ideological framing

While rooted in Korean nationalism, the war was cast as a frontline test of communism vs capitalism in the emerging global Cold War.

Evaluate causes of the Korean War

The war’s origins reflected both local nationalist struggles and superpower calculations, making Korea a flashpoint where regional and global conflicts merged.

List the course of the Korean War

• North Korean invasion

• UN intervention 

• Inchon landing 

• Chinese intervention 

• Stalemate and armistice 

• Human cost

Describe North Korean invasion

North Korean invasion 25 June 1950:

DPRK forces crossed the 38th parallel, capturing Seoul within three days.

Describe UN intervention

• the US secured a resolution for a UN-led force of 16 nations,

  • Exploiting the Soviet boycott of the Security Council,

  • dominated by American troops.

Describe Inchon landing

Inchon landing (15 Sept 1950):

• General MacArthur’s amphibious strike recaptured Seoul

• drove DPRK forces back to the Yalu River.

Describe Chinese intervention

Chinese intervention Oct 1950,

• ~300,000 Chinese “volunteers” crossed the Yalu,

• inflicting heavy casualties

• pushing UN troops back to the 38th parallel.

Describe stalemate and armistice

• From 1951–53, the conflict settled into trench warfare.

• The armistice (27 July 1953) restored the pre-war border.

Describe human cost

An estimated

• 3 million deaths, including

• 36,000 US soldiers,

• 600,000 Chinese,

• millions of Korean civilians,

• left the peninsula devastated.

Evaluate the course of the Korean War

The war showed how quickly Cold War crises could escalate from local conflicts to multi-state wars, yet ultimately ended in a costly stalemate.

List impact and significance of the Korean War

• Globalisation of the Cold War

• Militarisation

• Alliance expansion

• Enduring division

Describe globalisation of the Cold War

• The US demonstrated readiness to fight militarily worldwide to contain communism,

• shifting from rhetoric to armed intervention.

Describe militarisation

• Defence spending tripled from $13bn (1950) to $50bn (1953),

• fulfilling NSC-68’s call for rearmament.

Describe alliance expansion

• The war spurred creation of SEATO (1954)

• accelerated Japan’s rearmament under US protection.

Describe enduring division

• Korea remained divided,

• hostility entrenched,

• Asia firmly incorporated into Cold War geopolitics.

Evaluate impact and significance of the Korean War

The Korean War entrenched the Cold War as a truly global and militarised conflict, demonstrating both the risks of superpower confrontation and the resilience of containment.

Post revisionist views on the Korean War

Warren Cohen describes it as an “ideologically driven, militarized conflict” which “threatened the very survival of the globe.” 

“Comedy of errors” - John Lewis Gaddis