At one point in 1966–67, the hawkish Rostow advocated that the United States invade North Vietnam, even if it meant war with China, a course of action that McNamara rejected as likely to cause a nuclear war. Rostow always maintained that had his advice to the president to invade North Vietnam been taken in 1966 or 1967, the war would have been won, telling Karnow in an interview in 1981 that he was disappointed that Johnson rejected his advice to invade North Vietnam. Johnson remembered how the approach of American forces upon the Yalu river in 1950 to China intervening in the Korean War, and he was very fearful that an American invasion of North Vietnam would once again led to a war with China, which now had nuclear weapons. For this reason, Johnson was always against invading North Vietnam as the risks of a nuclear war with China were too awful for him to consider. Through Rostow was disappointed that Johnson rejected his advice to invade North Vietnam, he knew better than to stridently press that idea as that would annoy the president, and instead he brought up the idea of invading North Vietnam every so often a couple of months after Johnson last rejected it. Rostow also chaired a secret "psychological strategy committee" whose purpose was to supply "correct facts" about the Vietnam war to Congress, the media and the American people in general.