Initially, the Americans thought that the bombings would not last for a very long period. The thought in their minds was that it would only take a few days of bombing.
They also thought that the North Vietnam would stop supporting the Viet Cong. The Viet Cong were fighting a guerrilla war in the south and in this period of war, they had received a lot of support from the government and military army of North Vietnam. The Viet Cong were communist sympathizers who were fighting to make South Vietnam a communist state with the support of other communist states.