 The Cambodian Campaign ( also known as the Cambodian <unk> and the Cambodian Invasion ) was a series of military operations conducted in eastern Cambodia during 1970 by the United States and the Republic of Vietnam ( South Vietnam ) ( <unk> ) during the Vietnam War . These invasions were a result of the policy of President Richard Nixon . A total of 13 major operations were conducted by the Army of the Republic of Vietnam ( ARVN ) between 29 April and 22 July and by US forces between 1 May and 30 June . 
