On 17 February 1979, China invaded Vietnam, aiming to capture the capitals of Vietnam’s northern border provinces in order to force a Vietnamese withdrawal from Cambodia. Despite resistance from local militia living in the northern border provinces, the People’s Liberation Army of China (PLA) captured Cao Bằng and Lào Cai after three weeks and Lạng Sơn after a month.
After taking Lạng Sơn, China announced that it would not move deeper into Vietnam, apparently after meeting unexpectedly harsh resistance by well-trained Vietnamese forces equipped with Soviet and captured American weapons. Not only well equipped
As well as the People’s Army of Vietnam () benefitting from local support and being unexpectedly well-equipped, the Vietnamese government had ordered an effective policy of general mobilization through a plan for full military conscription. Subsequently, the PLA withdrew their forces on 16 March.