The Cambodian coup of 1970 refers to the removal of the Cambodian Head of State, Prince Norodom Sihanouk, after a vote in the National Assembly on 18 March 1970. Emergency powers were subsequently invoked by the Prime Minister Lon Nol, who became effective head of state. The coup led ultimately to the proclamation of the Khmer Republic (République khmère) later that year, and was a turning point in the Cambodian Civil War. Not a monarchy any longer, Cambodia received the semi-official appellation "État du Cambodge" (State of Cambodia) in the intervening six months after the coup, until the republic was proclaimed.
It also marked the point at which Cambodia became substantially involved in the Second Indochina War, as Lon Nol issued an ultimatum to Vietnamese forces to leave Cambodia.
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