The Mukden Incident, or Manchurian Incident, known in Chinese as the 9.18 Incident, was a false flag event staged by Japanese military personnel as a pretext for the 1931 Japanese invasion of Manchuria.
On September 18, 1931, Lieutenant Suemori Kawamoto of the Independent Garrison Unit of the 29th Japanese Infantry Regiment detonated a small quantity of dynamite close to a railway line owned by Japan's South Manchuria Railway near Mukden. The explosion was so weak that it failed to destroy the track, and a train passed over it minutes later. The Imperial Japanese Army accused Chinese dissidents of the act and responded with a full invasion that led to the occupation of Manchuria, in which Japan established its puppet state of Manchukuo six months later. The deception was exposed by the Lytton Report of 1932, leading Japan to diplomatic isolation and its March 1933 withdrawal from the League of Nations.
The bombing act is known as the Liutiao Lake Incident, and the entire episode of events is known in Japan as the Manchurian Incident and in China as the September 18 Incident.