The Sino-Vietnamese War (also known by various other names) was a border war fought between China and Vietnam in early 1979. China launched an offensive in response to Vietnam's actions against the Khmer Rouge in 1978, which ended the rule of the Chinese-backed Khmer Rouge. Both China and Vietnam claimed victory in the last of the Indochina Wars.

Chinese forces invaded northern Vietnam and captured several cities near the border. On 6 March 1979, China declared that the gate to Hanoi was open and that their punitive mission had been achieved. Chinese troops then withdrew from Vietnam. As Vietnamese troops remained in Cambodia until 1989, China was unsuccessful in its goal of dissuading Vietnam from involvement in Cambodia. Following the dissolution of the Soviet Union in 1991, the Sino-Vietnamese border was finalized. Although unable to deter Vietnam from ousting Pol Pot from Cambodia, China demonstrated that its Cold War communist adversary, the Soviet Union, was unable to protect its Vietnamese ally.