Skip to content
Photograph of Kim Il Sung in Moscow, March 1949

Korean War Origins, 1945-1950

Who started the Korean War?

This collection of primary source documents helps to answer this defining question about one of the most significant flashpoints of the twentieth century.

By the end of 1948, the allied occupation of the Korean Peninsula had ended, leaving two rival states—North Korea and South Korea—on a collision course. Tensions intensified as each side vied for supremacy, culminating in Kim Il Sung's pivotal meetings with Stalin in the spring of 1950. Armed with Soviet backing and citing reports of a South Korean military buildup, Kim sought substantial aid from Moscow to prepare for an invasion.

Although North Korea alleged that South Korea initiated the conflict by crossing the 38th Parallel, documents in this collection clearly demonstrate that North Korea made the first move. The collection sheds light on the lead-up to the war, offering records on the failed international diplomacy that led to Korea's division, Kim Il Sung’s extensive consultations with Soviet and Chinese leaders, Communist bloc assessments of South Korea, and the evolution of Kim’s war plans.

American perspectives are also featured, with declassified Central Intelligence Agency reports offering unique insights into the dynamics unfolding in North and South Korea during this critical period. Together, these materials provide a nuanced and comprehensive understanding of the complex factors that ignited the Korean War.

For more coverage of the Korean War on the Digital Archive, see the collections: Korean War, 1950-1953; Korean War Armistice; China and the Korean War; and Korean War Biological Warfare Allegations

For a collections resource guide see The Korean War: Collections & Resources on DigitalArchive.org.

 

Photograph of Kim Il Sung in Moscow, March 1949

Timeline