Vietnam fought China in 1979. The two-month border war, triggered by Vietnam’s invasion of Cambodia to remove the Chinese-backed Khmer Rouge government, cost tens of thousands of lives on both sides and ended without a clear military result. Vietnam held its positions. China withdrew. The war left a deep imprint on Vietnamese strategic culture: the understanding that China is a permanent neighbor with permanent interests in Vietnamese subordination, and that resistance — rather than accommodation — is the posture that Vietnamese sovereignty requires.