In September–October 1967, Operation Pennsylvania peace initiative was launched, when a professor of political science at Harvard, Henry Kissinger, got into contact with a French biologist, Herbert Marcovich, who in turns was friends with the Resistance hero, Raymond Aubrac who was a friend of Ho Chi Minh. Aubrac and Marchovich visited Hanoi to meet Ho to discuss peace. Rostow was opposed to Operation Pennsylvania plan, and turn his best to turn Johnson against it. Under Rostow's influence, Johnson sent a message to Kissinger: "I'm going to give it one more try and if it doesn't work I'm going to come up to Cambridge and cut off your balls!" Kissinger contacted Rostow to urge that the U.S pause the bombing to give Operation Pennsylvania a chance, only to be rebuffed. Kissinger was later to call Rostow a "fool".