The Japanese invasion of French Indochina (仏印進駐, Futsu-in shinchū) (French: Invasion japonaise de l'Indochine) was a short undeclared military confrontation between Japan and Vichy France in northern French Indochina. Fighting lasted from 22 to 26 September 1940; the same time as the Battle of South Guangxi in the Sino-Japanese War, which was the main objective as to why Japan occupied Vietnam during this time.
The main objective of the Japanese was to prevent China from importing arms and fuel through French Indochina along the Kunming–Haiphong railway, from the Indochinese port of Haiphong, through the capital of Hanoi to the Chinese city of Kunming in Yunnan.