Battles of Khalkhin Gol
The Battles of Khalkhin Gol (Russian: Бои на Халхин-Голе, romanized: Boy na Khalkhin-Gole; Mongolian: Халхын голын байлдаан, romanized: Khalkhyn golyn baildaan), known in Japan as the Nomonhan Incident (Japanese: ノモンハン事件, Hepburn: Nomonhan jiken) after Nomonhan Burd Obo, were the decisive engagements of the undeclared Soviet–Japanese border conflicts which involved the Soviet Union, Mongolia, Japan, and Manchukuo in 1939. The conflict is named after the river Khalkhin Gol, which passes through the battlefield.