In particular, Rostow persistently argued to the president that a programme of sustained bombing would force North Vietnam to cease its support of the Viet Cong and thus win the war. Rostow believed that strategic bombing alone would be enough to force North Vietnam to capitulate, and became the main advocate in the White House of Operation Rolling Thunder, the bombing offensive launched against North Vietnam in February 1965. Initially, Rostow believed in only bombing certain targets as a way of warning Hanoi to cease supporting the Viet Cong, but he changed his mind, coming to favour an all-out bombing offensive that would completely destroy the economy of North Vietnam. Reflecting the lessons of the Oil Plan, Rostow in particular believed that the destruction of the North Vietnamese oil shortage facilities and the hydroelectric grid would so economically cripple North Vietnam that the war would be won, and he pressed Johnson to end the restrictions on bombing oil shortage tanks and hydro plants. Rostow was opposed by Harriman, who like him had spent much of World War II living in England; however, Harriman had first-hand observed how German bombing of British cities had hardened the will of the British public, and he now argued that American bombing on North Vietnam was having the same effect on the North Vietnamese public. The fact that Rostow had arrived in London in fall of 1942, when the worse of the German bombing was over, while Harriman as a special envoy for President Roosevelt had witnessed first-hand the "Blitz" against London and other British cities in the winter of 1940–41 contributed to their differing assessments of the effects of bombing. Based on his experiences in wartime, Harriman called the Rostow Thesis "the stick without the carrot".