original_query: What role did the Chinese invasion of Vietnam play in the poor relations between unified Vietnam and the Khmer regime?
query: What role did the Chinese invasion of Vietnam play in the poor relations between unified Vietnam and the Khmer Rouge?
answer: The Chinese invasion of Vietnam did not directly improve relations between Vietnam and the Khmer Rouge.  The Khmer Rouge's massacre of ethnic Vietnamese and attacks on Vietnam preceded the Chinese invasion.  While the Khmer Rouge allied with China, this was insufficient to prevent Vietnam's invasion and destruction of the Khmer Rouge regime.