The Cambodian–Vietnamese War ( ) , known Know in Vietnam as the Counter-offensive Defending on the Southwestern border ( ) , was an armed conflict Hostile_encounter between the Socialist Republic of Vietnam and Democratic Kampuchea .

The Sino-Soviet split re-emerged Coming_to_be following the lull during the Vietnam War and conflict between North Vietnam and its Cambodian allies in the Royal Government of the National Union of Kampuchea , and the newly-formed Democratic Kampuchea begun Process_start almost immediately in a series of border raids by the Khmer Rouge that erupted into the Cambodian–Vietnamese War , with Chinese forces directly invading in the Sino-Vietnamese War and subsequent border conflicts .