President Truman justified intervention in Korea by comparing events there to the crisis in the European nation of Czechoslovakia.
In his address to the American public on June 27, 1950, President Truman drew a parallel between the North Korean invasion of South Korea and the 1938 crisis in Czechoslovakia, known as the Munich Crisis. During the Munich Crisis, Nazi Germany, under Adolf Hitler, demanded the annexation of parts of Czechoslovakia, specifically the Sudetenland. British Prime Minister Neville Chamberlain and French Premier Édouard Daladier agreed to give in to Hitler's demands in an attempt to appease him and avoid war. This event is often seen as a symbol of failed appeasement and the broader failure to confront aggression.
President Truman used the Munich Crisis as a cautionary tale, arguing that appeasement had been disastrous in Europe and that it was necessary to confront aggression in Korea to prevent further aggression and maintain global stability. By comparing the events in Korea to the Munich Crisis, Truman sought to rally international support and justify American military intervention in defense of South Korea.