Kennedy had no illusions about the willingness of the Soviet Union to cooperate with the United States in promoting world order. As Averell Harriman remembered, "He had a very clear conception of the Soviet Union and communism . . . he recognized the basic and fundamental difference between us-- their desire to communize the world, and our desire to frustrate them in their design."38 But Kennedy also believed that the Soviets acted primarily in terms of their national interest, defined by power rather than ideology, and could therefore be expected to behave reasonably in the face of overwhelming American power. This was the fundamental premise underlying arms control, as conceived and implemented by the Kennedy administration. As opposed to disarmament advocates, whose assumptions about international relations were considerably more optimistic, arms controllers viewed world order as deriving from a "balance of power." The key to stability therefore was not to dismantle existing weapons stockpiles but rather to insure a situation of mutual nuclear deterrence. This could be achieved not only through negotiated agreements but also through unilateral defense policies, taking into account the joint interests of the United States and Soviet Union in avoiding and/or limiting nuclear war. Perhaps Kennedy and the arms controllers around him were somewhat naive in their expectations about the degree of superpower collaboration possible in an area so mutually dangerous as nuclear war. Nevertheless, they were the first to recognize the inherent ambivalences in U.S. relations with the Soviet Union and to design a strategy of arms control reflective of those ambivalences.