Wilson blamed Rostow for the failure of Operation Sunflower, telling his Foreign Secretary George Brown: "I suspect that Rostow himself was largely responsible for the misunderstandings during the Kosygin visit and may well have reported to the president in the light of responsibility". Karnow wrote it is no means certain that Wilson's claim that a "historic opportunity" to end the war in Vietnam in 1967 had been squandered as all Kosygin was promising was to pressure Ho to accept a ceasefire and as he himself noted that when the Soviets pressured the North Vietnamese to do something that they did not want to do, they just drew closer to China. Soviet pressure on North Vietnam tended to most effective in conjugation with China, and in 1967 the Chinese were attacking the Soviets in the most violent terms, accusing them of abandoning true communism, making any possibility of Sino-Soviet pressure on North Vietnam most unlikely. Karnow wrote at most Operation Sunflower offered was a chance to begin negotiations to end the war, and Johnson and Rostow shunned that chance.