In 1955, Sihanouk abdicated in favour of his father to participate in politics and was elected prime minister. Upon his father's death in 1960, Sihanouk again became head of state, taking the title of prince. As the Vietnam War progressed, Sihanouk adopted an official policy of neutrality in the Cold War. Sihanouk allowed the Vietnamese communists to use Cambodia as a sanctuary and a supply route for their arms and other aid to their armed forces fighting in South Vietnam. This policy was perceived as humiliating by many Cambodians. In December 1967 Washington Post journalist Stanley Karnow was told by Sihanouk that if the US wanted to bomb the Vietnamese communist sanctuaries, he would not object unless Cambodians were killed.