The Nixon administration’s decision in 1969 to begin the systematic bombing of Cambodia fundamentally altered the nature of the war the US was fighting in Vietnam for all parties involved – Americans, North Vietnamese, South Vietnamese, and especially the Cambodians. Cambodia had largely remained isolated from the fighting even as it escalated in 1965. North Vietnamese troops and Viet Cong cadres had been using the border territory as sanctuaries, but they remained along the border and did not engage the Cambodian population in any way that substantially altered the strategic situation or affected the peasants living in the region. The Nixon administration changed all that by undertaking four actions: 1) initiating a secret bombing campaign in 1969 to disrupt North Vietnamese troops; 2) supporting the overthrow of Prince Sihanouk and his replacement with Lon Nolo in March 1970; 3) authorizing a joint South Vietnamese–US invasion of Cambodia in May–June 1970; and 4) continuing with the bombing of Cambodia until August 1973, many months after the signing of the Paris Peace agreement. The results for Cambodia led to a collapse of the government and the takeover by the Khmer Rouge in April 1975.