On this day in 1950, U.S.-backed South Korean President Syngman Rhee ordered the mass murder of suspected communists following the outbreak of the Korean War, resulting in the summary executions of 60,000 - 200,000 Koreans.

Two days prior, the North Korean People's Army had crossed the 38th parallel to liberate South Korea from the U.S. collaborationist Republic of Korea (ROK). The ROK was established by the occupying U.S. military government in 1948, following the conclusion of World War II.

On June 27th, 1950, ROK President Syngman Rhee ordered the mass executions of people associated with the National Bodo League, a state-run re-education program for suspected communists, and the South Korean Worker's Party (WPSK).

Over the following weeks, ROK officials executed many thousands of Koreans. Estimates of the total killed vary widely, from 60,000 to 200,000. Official U.S. documents show that American officers witnessed and photographed the massacre, and in at least one case, an American lieutenant colonel approved of one episode of mass executions.

The South Korean government falsely blamed the murders on communists led by Kim Il-sung and suppressed public knowledge of the massacre for decades afterward. Beginning in the 1990s, several corpses were excavated from mass graves, raising public awareness of the massacre.

In 2009, the National Archives in Washington D.C. released declassified photographs of U.S. soldiers at execution sites, confirming that the American military knew and did nothing to stop the mass killing.