 When full-scale war broke out in the Marco Polo Bridge Incident in July 1937, its forces participated in Battle of Beiping-Tianjin and Operation Chahar.Later, Kwantung forces supported the war in China from time to time.However, by the late 1930s the Kwantung Army's much vaunted reputation was severely challenged during the Soviet–Japanese border conflicts that Japan had fought against the Soviet Union in northern Manchukuo since 1932.