 The Cambodian – Vietnamese War was an armed conflict between the Socialist Republic of Vietnam and Democratic Kampuchea . The war began with isolated clashes along the land and maritime boundaries of Vietnam and Kampuchea between 1975 and 1977 , occasionally involving division @-@ sized military formations . On 25 December 1978 , Vietnam launched a full @-@ scale invasion of Kampuchea and subsequently occupied the country . The war ended with the withdrawal of Vietnamese forces from Kampuchea on 20 May 1993 .

## Background

In 1975, Vietnamese forces were stationed in the southern half of Kampuchea, including the capital Ph