Abstract The recent increase in military cooperation between Cambodia and China has raised concerns about Cambodia’s neutrality and its role in regional power dynamics. Will this military relationship help Cambodia become a smart neutral nation or is it a pawn in China’s ambitious political game? The study and assessment of Cambodia-China relations in the military field and their impact on Vietnam will be very necessary in the current international situation. Through the historical approach and on the basis of analysis of international relations, the article clearly analyzes the reasons for the increased cooperation between China and Cambodia in the military field in the twenty-first century. Concurrently, the article assesses the impact of this issue on Vietnam and gives opinions in Cambodia's neutral foreign policy. Keywords: Cambodia, China, Military, Viet Nam, International relation