Kennedy also charged that Rostow was too fixated on Vietnam, saying he seemed to have an obsession with that country as he spent much time talking about Vietnam. Rostow believed in the "Domino Theory", predicating that if South Vietnam fell, the rest of Southeast Asia would also fall like so dominoes, and ultimately India would fall as well. As early as June 1961, Rostow was advising Kennedy to bomb North Vietnam. During the Berlin crisis of 1961, Rostow advised Kennedy: "We must find ways of putting pressure on Khrushchev's side of the line with conventional forces or other means...We must begin now to present Khrushchev with the risk that if he heightens the Berlin crisis, we and the West Germans may take action that will cause East Germany to come unstruck". The particular action that Rostow advised Kennedy to take was to "take and hold a piece of territory in East Germany that Khrushchev may not wish to lose (for example, Magdeburg)". Kennedy rejected this advice as too dangerous, stating that having U.S forces seize part of East Germany would almost certainly cause a nuclear war with the Soviet Union. Later that year, Rostow became Director of the State Department's Policy Planning Staff. At the time, Kennedy commented: "Walt is a fountain of ideas; perhaps one in ten of them is absolutely brilliant. Unfortunately six or seven are not merely unsound, but dangerously so. I admire his creativity, but it will be more comfortable to have him creating at some remove from the White House".